2008 : WHAT HAVE YOU CHANGED YOUR MIND ABOUT? WHY?

I have changed my mind about the nature of perception. I thought that a goal of perception is to estimate properties of an objective physical world, and that perception is useful precisely to the extent that its estimates are veridical. After all, incorrect perceptions beget incorrect actions, and incorrect actions beget fewer offspring than correct actions. Hence, on evolutionary grounds, veridical perceptions should proliferate.

Although the image at the eye, for instance, contains insufficient information by itself to recover the true state of the world, natural selection has built into the visual system the correct prior assumptions about the world, and about how it projects onto our retinas, so that our visual estimates are, in general, veridical. And we can verify that this is the case, by deducing those prior assumptions from psychological experiments, and comparing them with the world. Vision scientists are now succeeding in this enterprise. But we need not wait for their final report to conclude with confidence that perception is veridical. All we need is the obvious rhetorical question: Of what possible use is non-veridical perception?

I now think that perception is useful because it is not veridical. The argument that evolution favors veridical perceptions is wrong, both theoretically and empirically. It is wrong in theory, because natural selection hinges on reproductive fitness, not on truth, and the two are not the same: Reproductive fitness in a particular niche might, for instance, be enhanced by reducing expenditures of time and energy in perception; true perceptions, in consequence, might be less fit than niche-specific shortcuts. It is wrong empirically: mimicry, camouflage, mating errors and supernormal stimuli are ubiquitous in nature, and all are predicated on non-veridical perceptions. The cockroach, we suspect, sees little of the truth, but is quite fit, though easily fooled, with its niche-specific perceptual hacks. Moreover, computational simulations based on evolutionary game theory, in which virtual animals that perceive the truth compete with others that sacrifice truth for speed and energy-efficiency, find that true perception generally goes extinct.

It used to be hard to imagine how perceptions could possibly be useful if they were not true. Now, thanks to technology, we have a metaphor that makes it clear — the windows interface of the personal computer. This interface sports colorful geometric icons on a two-dimensional screen. The colors, shapes and positions of the icons on the screen are not true depictions of what they represent inside the computer. And that is why the interface is useful. It hides the complexity of the diodes, resistors, voltages and magnetic fields inside the computer. It allows us to effectively interact with the truth because it hides the truth.

It has not been easy for me to change my mind about the nature of perception. The culprit, I think, is natural selection. I have been shaped by it to take my perceptions seriously. After all, those of our predecessors who did not, for instance, take their tiger or viper or cliff perceptions seriously had less chance of becoming our ancestors. It is apparently a small step, though not a logical one, from taking perception seriously to taking it literally. 

Unfortunately our ancestors faced no selective pressures that would prevent them from conflating the serious with the literal: One who takes the cliff both seriously and literally avoids harms just as much as one who takes the cliff seriously but not literally. Hence our collective history of believing in flat earth, geocentric cosmology, and veridical perception. I should very much like to join Samuel Johnson in rejecting the claim that perception is not veridical, by kicking a stone and exclaiming "I refute it thus." But even as my foot ached from the ill-advised kick, I would still harbor the skeptical thought, "Yes, you should have taken that rock more seriously, but should you take it literally?"

Sometimes the later Roman empire seems very long ago and far away, but at other times, when we explore Edward Gibbon's famous claim to have described the triumph of "barbarism and religion", it can seem as fresh as next week.  And we always know that we're supposed root for the Romans.  When I began my career as historian thirty years ago, I was all in favor of those who were fighting to preserve the old order.  "I'd rather be Belisarius than Stilicho," I said to my classes often enough that they heard it as a mantra of my attitude — preferring the empire-restoring Roman general of the sixth-century to the barbarian general who served Rome and sought compromise and adjustment with neighbors in the fourth.  

But a career as a historian means growth, development, and change.  I did what the historian — as much a scientist as any biochemist, as the German use of the word Wissenschaft for what both practice — should do:  I studied the primary evidence, I listened to and participated in the debates of the scholars.  I had moments when a new book blew me away, and others when I read the incisive critique of the book that had blown me away and thought through the issues again.  I've been back and forth over a range of about four centuries of late Roman history many times now, looking at events, people, ideas, and evidence in different lights and moods.

What I have found is that the closer historical examination comes to the lived moment of the past, the harder it is to take sides with anybody.  And it is a real fact that the ancient past (I'm talking now about the period from 300-700 CE) draws closer and closer to us all the time.  There is a surprisingly large body of material that survives and really only a handful of hardy scholars sorting through it.  Much remains to be done:  The sophist Libanius of Antioch in the late fourth century, partisan for the renegade 'pagan' emperor Julian, left behind a ton of personal letters and essays that few have read, only a handful have been translated, and so only a few scholars have really worked through his career and thought — but I'd love to read, and even more dearly love to write, a good book about him someday.  In addition to the books, there is a growing body of archaeological evidence as diggers fan out across the Mediterranean, Near East, and Europe, and we are beginning to see new kinds of quantitative evidence as well — climate change measured from tree-ring dating, even genetic analysis that suggests that my O'Donnell ancestors came from one of the most seriously inbred populations (Ireland) on the planet — and right now the argument is going on about the genetic evidence for the size of the Anglo-Saxon migrations to Britain.  We know more than we ever did, and we are learning more all the time, and with each decade, we get closer and closer to even the remote past.  

When you do that, you find that the past is more a tissue of  choices and chances than we had imagined, that fifty or a hundred years of bad times can happen — and can end and be replaced by the united work of people with heads and hearts that makes society peaceful and prosperous again; or the opportunity can be kicked away.  

And we should remember that when we root for the Romans, there are contradictory impulses at work.  Rome brought the ancient world a secure environment (Pompey cleaning up the pirates in the Mediterranean was a real service), a standard currency, and a huge free trade zone.  Its taxes were heavy, but the wealth it taxed so immense that it could support a huge bureaucracy for a long time without damaging local prosperity.  Fine:  but it was an empire by conquest, ruled as a military dictatorship, fundamentally dependent on a slave economy, and with no clue whatever about the realities of economic development and management.  A prosperous emperor was one who managed by conquest or taxation to bring a flood of wealth into the capital city and squander it as ostentatiously as possible.  Rome "fell", if that's the right word for it, partly because it ran out of ideas for new peoples to plunder, and fell into a funk of outrage at the thought that some of the neighboring peoples preferred to move inside the empire's borders, settle down, buy fixer-upper houses, send their kids to the local schools, and generally enjoy the benefits of civilization.  (The real barbarians stayed outside.)  Much of the worst damage to Rome was done by Roman emperors and armies thrashing about, thinking they were preserving what they were in fact destroying.

So now I have a new mantra for my students:  "two hundred years is a long time."  When we talk about Shakespeare's time or the Crusades or the Roman Empire or the ancient Israelites, it's all too easy to talk about centuries as objects, a habit we bring even closer to our own time, but real human beings live in the short window of a generation, and with ancient lifespans shorter than our own, that window was brief.  We need to understand and respect just how much possibility was there and how much accomplishment was achieved if we are to understand as well the opportunities that were squandered.  Learning to do that, learning to sift the finest grains of evidence with care, learning to learn from and debate with others — that's how history gets done.  

The excitement begins when you discover that the past is constantly changing.

I've begun to rethink the way we teach students to engage in scientific research. I was trained, as a chemist, to use the classic scientific method: Devise a testable hypothesis, and then design an experiment to see if the hypothesis is correct or not. And I was told that this method is equally valid for the social sciences. I've changed my mind that this is the best way to do science. I have three reasons for this change of mind.

First, and probably most importantly, I've learned that one often needs simply to sit and observe and learn about one's subject before even attempting to devise a testable hypothesis. What are the physical capacities of the subject? What is the social and ecological structure in which it lives? Does some anecdotal evidence suggest the form that the hypothesis should take? Few granting agencies are willing to provide support for this step, but it is critical to the scientific process, particularly for truly innovative research. Often, a proposal to gain observational experience is dismissed as being a "fishing expedition"…but how can one devise a workable hypothesis to test without first acquiring basic knowledge of the system, and how better to obtain such basic knowledge than to observe the system without any preconceived notions?

Second, I've learned that truly interesting questions really often can't be reduced to a simple testable hypothesis, at least not without being somewhat absurd. "Can a parrot label objects?" may be a testable hypothesis, but actually isn't very interesting…what is interesting, for example, is how that labeling compares to the behavior of a young child, exactly what type of training might enable such learning and what type of training is useless, how far can such labeling transfer across exemplars, and….Well, you get the picture…the exciting part is a series of interrelated questions that arise and expand almost indefinitely.

Third, I've learned that the scientific community's emphasis on hypothesis-based research leads too many scientists to devise experiments to prove, rather than test, their hypotheses. Many journal submissions lack any discussion of alternative competing hypotheses: Researchers don't seem to realize that collecting data that are consistent with their original hypothesis doesn't mean that it is unconditionally true. Alternatively, they buy into the fallacy that absence of evidence for something is always evidence of its absence.

I'm all for rigor in scientific research — but let's emphasize the gathering of knowledge rather than the proving of a point.

I grew up infused with the idea of unification. It came first from religion, from my Jewish background. God was all over, was all-powerful, and had a knack for interfering with human affairs, at least in the Old Testament. He then appeared to have decided to be a bit shyer, sending a Son instead, and only revealing Himself through visions and prophecies. Needless to say, when, as a teenager, I started to get interested in science, this vision of an all-pervading God, stories of floods, commandments and plagues, started to become very suspicious. I turned to physics, idolizing Einstein and his science; here was a Jew that saw further, that found a way of translating this old monotheistic tradition into the universal language of science.

As I started my research career, I had absolutely no doubt that I wanted to become a theoretical physicist working on particle physics and cosmology. Why the choice? Simple: it was the joining of the two worlds, of the very large and the very small, that offered the best hope for finding a unified theory of all Nature, that brought together matter and forces into one single magnificent formulation, the final Platonist triumph. This was what Einstein tried to do for the last three decades of his life, although in his days it was more a search for unifying only half of the forces of Nature, gravity and electromagnetism.

I wrote dozens of papers related to the subject of unification, even my Ph.D. dissertation was on the topic. I was fascinated by the modern approaches to the idea, supersymmetry, superstrings, a space with extra, hidden dimensions. A part of me still is. But then, a few years ago, something snapped. It probably was brought by a combination of factors, a deeper understanding of the historical and cultural processes that shape scientific ideas. I started to doubt unification, finding it to be the scientific equivalent of a monotheistic formulation of reality, a search for God revealed in equations. Of course, had we the slightest experimental evidence in favor of unification, of supersymmetry and superstrings, I'd be the first popping the champagne open. But it's been over twenty years, and all attempts so far have failed. Nothing in particle accelerators, nothing in cryogenic dark matter detectors, no magnetic monopoles, no proton decay, all tell-tale signs of unification predicted over the years. Even our wonderful Standard Model of particle physics, where we formulate the unification of electromagnetism and the weak nuclear interactions, is not really a true unification: the theory retains information from both interactions in the form of their strengths or, in more technical jargon, of their coupling constants. A true unification should have a single coupling constant, a single interaction.

All of my recent anti-unification convictions can crumble during the next few years, after our big new machine, the Large Hadron Collider, is turned on. Many colleagues hope that supersymmetry will finally show its face. Others even bet on possible signs of extra dimensions revealed. However, I have a feeling things won't turn out so nicely. The model of unification, which is so aesthetically appealing, may be simply this, an aesthetically appealing description of Nature, which, unfortunately, doesn't correspond to physical reality. Nature doesn't share our myths. The stakes are high indeed. But being a mild agnostic, I don't believe until there is evidence. And then, there is no need to believe any longer, which is precisely the beauty of science.

When I was very little the question was easy. I simply assumed the whole Bible was true, albeit in a mysterious, grown-up sort of way. But once I learned something of science, at school and then at university, that unquestioning belief slid away.

Mathematics was especially important here, and I remember how entranced I was when I first saw the power of axiomatic systems. Those were logical structures that were as beautiful as complex crystals —  but far, far clearer. If there was one inaccuracy at any point in the system, you could trace it, like a scarcely visible stretching crack through the whole crystal; you could see exactly how it had to undermine the validity of far distant parts as well. Since there are obvious factual inaccuracies in the Bible, as well as repugnant moral commands, then —  just as with any tight axiomatic system —  huge other parts of it had to be wrong, as well. In my mind that discredited it all.

What I've come to see more recently is that the Bible isn't monolithic in that way. It's built up in many, often quite distinct layers. For example, the book of Joshua describes a merciless killing of Jericho's inhabitants, after that city's walls were destroyed. But archaeology shows that when this was supposed to be happening, there was no large city with walls there to be destroyed. On the contrary, careful dating of artifacts, as well as translations from documents of the great empires in surrounding regions, shows that the bloodthirsty Joshua story was quite likely written by one particular group, centuries later, trying to give some validity to a particular royal line in 7th century BC Jerusalem, which wanted to show its rights to the entire country around it. Yet when that Joshua layer is stripped away, other layers in the Bible remain. They can stand, or be judged, on their own.

A few of those remaining layers have survived only because they became taken up by narrow power structures, concerned with aggrandizing themselves, in the style of Philip Pullman's excellent books. But others have survived across the millennia for different reasons. Some speak to the human condition with poetry of aching beauty. And others —  well, there's a further reason I began to doubt the inanity of everything I couldn't understand.

A child age three, however intelligent, and however much it squinches his or her fact tight in concentration, still won't be able to grasp notions that are easy for us, such as 'century', or 'henceforth', let alone greater subtleties which 20th century science has clarified, such as 'simultaneity' or 'causality'. True and important things exist, which young children can't comprehend. It seems odd to be sure that we, adult humans, existing at this one particular moment in evolution, have no such limits.

I realized that the world  isn't divided into science on the one hand, and nonsense or arbitrary biases on the other. And I wonder now what might be worth looking for, hidden there, fleetingly in-between.

I thought that it would change people. I thought it would allow us to build a new world through which we could model new behaviors, values, and relationships. In the 90's, I thought the experience of going online for the first time would change a person's consciousness as much as if they had dropped acid in the 60's.

I thought Amazon.com was a ridiculous idea, and that the Internet would shrug off business as easily as it did its original Defense Department minders.

For now, at least, it's turned out to be different.

Virtual worlds like Second Life have been reduced to market opportunities: advertisers from banks to soft drinks purchase space and create fake characters, while kids (and Chinese digital sweatshop laborers) earn "play money" in the game only to sell it to lazier players on eBay for real cash.

The businesspeople running Facebook and MySpace are rivaled only by the members of these online "communities" in their willingness to surrender their identities and ideals for a buck, a click-through, or a better market valuation.

The open source ethos has been reinterpreted through the lens of corporatism as "crowd sourcing" — meaning just another way to get people to do work for no compensation. And even "file-sharing" has been reduced to a frenzy of acquisition that has less to do with music than it does the ever-expanding hard drives of successive iPods.

Sadly, cyberspace has become just another place to do business. The question is no longer how browsing the Internet changes the way we look at the world; it's which browser we'll be using to buy and sell stuff in the same old world.

I used to think you could predict the future.  In "Profiles of the Future," Arthur C. Clarke made it seem so easy.  And so did all those other experts who confidently predicted the paperless office, the artificial intelligentsia who for decades predicted "human equivalence in ten years," the nanotechnology prophets who kept foreseeing major advances toward molecular manufacturing within fifteen years, and so on. 

Mostly, the predictions of science and technology types were wonderful: space colonies, flying cars in everyone's garage, the conquest (or even reversal) of aging.  (There were of course the doomsayers, too, such as the population-bomb theorists who said the world would run out of food by the turn of the century.) 

But at last, after watching all those forecasts not come true, and in fact become falsified in a crashing, breathtaking manner, I began to question the entire business of making predictions.  I mean, if even Nobel prizewinning scientists such as Ernest Rutherford, who gave us essentially the modern concept of the nuclear atom, could say, as he did in 1933, that "We cannot control atomic energy to an extent which would be of any value commercially, and I believe we are not likely ever to be able to do so," and be so spectacularly wrong about it, what hope was there for the rest of us? 

And then I finally decided that I knew the source of this incredible mismatch between confident forecast and actual result.  The universe is a complex system in which countless causal chains are acting and interacting independently and simultaneously (the ultimate nature of some of them unknown to science even today).  There are in fact so many causal sequences and forces at work, all of them running in parallel, and each of them often affecting the course of the others, that it is hopeless to try to specify in advance what's going to happen as they jointly work themselves out.  In the face of that complexity, it becomes difficult if not impossible to know with any assurance the future state of the system except in those comparatively few cases in which the system is governed by ironclad laws of nature such as those that allow us to predict the  phases of the moon, the tides, or the position of Jupiter in tomorrow night's sky.  Otherwise, forget it. 

Further, it's an illusion to think that supercomputer modeling is up to the task of truly reliable crystal-ball gazing.  It isn't.  Witness the epidemiologists who predicted that last year's influenza season would be severe (in fact it was mild); the professional hurricane-forecasters whose models told them that the last two hurricane seasons would be monsters (whereas instead they were wimps).  Certain systems in nature, it seems, are computationally irreducible phenomena, meaning that there is no way of knowing the outcome short of waiting for it to happen. 

Formerly, when I heard or read a prediction, I believed it.  Nowadays I just roll my eyes, shake my head, and turn the page.

Where once I would have striven to see Incan child sacrifice 'in their terms', I am increasingly committed to seeing it in ours. Where once I would have directed attention to understanding a past cosmology of equal validity to my own, I now feel the urgency to go beyond a culturally-attuned explanation and reveal cold sadism, deployed as a means of social control by a burgeoning imperial power.

In Cambridge at the end of the 70s, I began to be inculcated with the idea that understanding the internal logic and value system of a past culture was the best way to do archaeology and anthropology. The challenge was to achieve this through sensitivity to context, classification and symbolism. A pot was no longer just a pot, but a polyvalent signifier, with a range of case-sensitive meanings. A rubbish pit was no longer an unproblematic heap of trash, but a semiotic entity embodying concepts of contagion and purity, sacred and profane. A ritual killing was not to be judged bad, but as having validity within a different worldview.

Using such 'contextual' thinking, a lump of slag found in a 5000 BC female grave in Serbia was no longer seen as chance contaminant — bi-product garbage from making copper jewelry. Rather it was a kind of poetic statement bearing on the relationship between biological and cultural reproduction. Just as births in the Vin?a culture were attended by midwives who also delivered the warm but useless slab of afterbirth, so Vinca culture ore was heated in a clay furnace that gave birth to metal. From the furnace — known from many ethnographies to have projecting clay breasts and a graphically vulvic stoking opening — the smelters delivered technology's baby. With it came a warm but useless lump of slag. Thus the slag in a Vinca woman's grave, far from being accidental trash, hinted at a complex symbolism of gender, death and rebirth.

So far, so good: relativism worked as a way towards understanding that our industrial waste was not theirs, and their idea of how a woman should be appropriately buried not ours. But what happens when relativism says that our concepts of right and wrong, good and evil, kindness and cruelty, are inherently inapplicable? Relativism self-consciously divests itself of a series of anthropocentric and anachronistic skins — modern, white, western, male-focused, individualist, scientific (or 'scientistic') — to say that the recognition of such value-concepts is radically unstable, the 'objective' outsider opinion a worthless myth.

My colleague Andy Wilson and our team have recently examined the hair of sacrificed children found on some of the high peaks of the Andes. Contrary to historic chronicles that claim that being ritually killed to join the mountain gods was an honour that the Incan rulers accorded only to their own privileged offspring, diachronic isotopic analyses along the scalp hairs of victims indicate that it was peasant children, who, twelve months before death, were given the outward trappings of high status and a much improved diet to make them acceptable offerings. Thus we see past the self-serving accounts of those of the indigenous elite who survived on into Spanish rule. We now understand that the central command in Cuzco engineered the high-visibility sacrifice of children drawn from newly subject populations. And we can guess that this was a means to social control during the massive, 'shock & awe' style imperial expansion southwards into what became Argentina.

But the relativists demur from this understanding, and have painted us as culturally insensitive, ignorant scientists (the last label a clear pejorative). For them, our isotope work is informative only as it reveals 'the inner fantasy life of, mostly, Euro-American archaeologists, who can't possibly access the inner cognitive/cultural life of those Others.' The capital 'O' is significant. Here we have what the journalist Julie Burchill mordantly unpacked as 'the ever-estimable Other' — the albatross that post-Enlightenment and, more importantly, post-colonial scholarship must wear round its neck as a sign of penance.

We need relativism as an aid to understanding past cultural logic, but it does not free us from a duty to discriminate morally and to understand that there are regularities in the negatives of human behaviour as well as in its positives. In this case, it seeks to ignore what Victor Nell has described as 'the historical and cross-cultural stability of the uses of cruelty for punishment, amusement, and social control.' By denying the basis for a consistent underlying algebra of positive and negative, yet consistently claiming the necessary rightness of the internal cultural conduct of 'the Other', relativism steps away from logic into incoherence.

My academic experience, mainly at Columbia University from 1946-1978, instilled the following firm beliefs:

The role of the Professor, reflecting the mission of the University, is research and dissemination of the knowledge gained. However, the Professor has many citizenship obligations: to his community, State and Nation, to his University, to his field of research, e.g. physics, to his students. In the latter case, one must add to the content knowledge transferred, the moral and ethical concerns that science brings to society. So scientists have an obligation to communicate their knowledge, popularize, and whenever relevant, bring his knowledge to bear on the issues of the time. However, additionally, scientists play a large role in advisory boards and systems from the President's Advisory system all the way to local school boards and PTAs. I have always believed that the above menu more or less covered all the obligations and responsibilities of the scientist. His most sacred obligation is to continue to do science. Now I know that I was dead wrong.

Taking even a cursory stock of current events, I am driven to the ultimately wise advice of my Columbia mentor, I.I. Rabi, who, in our many corridor bull sessions, urged his students to run for public office and get elected. He insisted that to be an advisor (he was an advisor to Oppenheimer at Los Alamos, later to Eisenhower and to the AEC) was ultimately an exercise in futility and that the power belonged to those who are elected. Then, we thought the old man was bonkers. But today......

Just look at our national and international dilemmas: global climate change (U.S. booed in Bali); nuclear weapons (seventeen years after the end of the Cold War, the U.S. has over 7,000 nuclear weapons, many poised to instant flight. Who decided?); stem cell research (still hobbled by White House obstacles). Basic research and science education are rated several nations below "Lower Slobovenia", our national deficit will burden the nation for generations, a wave of religious fundamentalism, an endless war in Iraq and the growing security restrictions on our privacy and freedom (excused by an even more endless and mindless war on terrorism) seem to be paralyzing the Congress. We need to elect people who can think critically.

A Congress which is overwhelmingly dominated by lawyers and MBAs makes no sense in this 21st century in which almost all issues have a science and technology aspect. We need a national movement to seek out scientists and engineers who have demonstrated the required management and communication skills. And we need a strong consensus of mentors that the need for wisdom and knowledge in the Congress must have a huge priority.

As a student, I was influenced by Claude Lévi-Strauss and even more by Noam Chomsky. Both of them dared talk about "human nature" when the received view was that there was no such thing. In my own work, I argued for a naturalistic approach in the social sciences. I took for granted that human cognitive dispositions were shaped by biological evolution and more specifically by Darwinian selection. While I did occasionally toy with evolutionary speculations, I failed to see at the time how they could play more than a quite marginal role in the study of human psychology and culture.

Luckily, in 1987, I was asked by Jacques Mehler, the founder and editor of Cognition, to review a very long article intriguingly entitled "The logic of social exchange: Has natural selection shaped how humans reason?" In most experimental psychology articles the theoretical sections are short and relatively shallow. Here, on the other hand, the young author, Leda Cosmides, was arguing in an altogether novel way for an ambitious theoretical claim. The forms of cooperation unique to and characteristic of humans could only have evolved, she maintained, if there had also been, at a psychological level, the evolution of a mental mechanism tailored to understand and manage social exchanges and in particular to detect cheaters. Moreover, this mechanism could be investigated by means of standard reasoning experiments.

This is not the place to go into the details of the theoretical argument — which I found and still find remarkably insightful — or of the experimental evidence — which I have criticized in detail with experiments of my own as inadequate. Whatever its shortcoming, this was an extraordinarily stimulating paper, and I strongly recommended acceptance of a revised version. The article was published in 1989 and the controversies it stirred have not yet abated.

Reading the work of Leda Cosmides and of John Tooby, her collaborator (and husband), meeting them shortly after, and initiating a conversation with them that has never ceased made me change my mind. I had known that we could reflect on the mental capacities of our ancestors on the basis of what we know of our minds; I now understood that we can also draw fundamental insights about our present minds through reflecting on the environmental problems and opportunities that have exerted selective pressure on our Paleolithic ancestors.

Ever since, I have tried to contribute to the development of evolutionary psychology, to the surprise and dismay of some of my more standard-social-science friends and also of some evolutionary psychologists who see me more as a heretic than a genuine convert. True, I have no taste or talent for orthodoxy. Moreover, I find much of the work done so far under the label "evolutionary psychology" rather disappointing. Evolutionary psychology will succeed to the extent that it causes cognitive psychologists to rethink central aspects of human cognition in an evolutionary perspective, to the extent, that is, that psychology in general becomes evolutionary.

The human species is exceptional in its massive investment in cognition, and in forms of cognitive activity — language, higher-order thinking, abstraction — that are as unique to humans as echolocation is to bats. Yet more than half of all work done in evolutionary psychology today is about mate choice, a mental activity found in a great many species. There is nothing intrinsically wrong in studying mate choice, of course, and some of the work done in this area is outstanding.

However the promise of evolutionary psychology is first and foremost to help explain aspects of human psychology that are genuinely exceptional among earthly species and that in turn help explain the exceptional character of human culture and ecology. This is what has to be achieved to a much greater extent than has been the case so far if we want more skeptical cognitive and social scientists to change their minds too.

I have become convinced that it would be of fundamental importance to know what a good state of consciousness is. Are there forms of subjective experience which — in a strictly normative sense — are better than others? Or worse? What states of consciousness should be illegal? What states of consciousness do we want to foster and cultivate and integrate into our societies? What states of consciousness can we force upon animals — for instance, in consciousness research itself? What states of consciousness do we want to show our children? And what state of consciousness do we eventually die in ourselves?

2007 has seen the rise of an important new discipline: "neuroethics". This is not simply a new branch of applied ethics for neuroscience — it raises deeper issues about selfhood, society and the image of man.  Neuroscience is now quickly transformed into neurotechnology. I predict that parts of neurotechnology will turn into consciousness technology. In 2002, out-of-body experiences were, for the first time, induced with an electrode in the brain of an epileptic patient.  In 2007 we saw the first two studies, published in Science, demonstrating how the conscious self can be transposed to a location outside of the physical body as experienced, non-invasively and in healthy subjects. Cognitive enhancers are on the rise. The conscious experience of will has been experimentally constructed and manipulated in a number of ways. Acute episodes of depression can be caused by direct interventions in the brain, and they have also been successfully blocked in previously treatment-resistant patients. And so on.

Whenever we understand the specific neural dynamics underlying a specific form of conscious content, we can in principle delete, amplify or modulate this content in our minds. So shouldn’t we have a new ethics of consciousness — one that does not ask what a good actionis, but that goes directly to the heart of the matter, asks what we want to do with all this new knowledge and what the moral value ofstates of subjective experience is?

Here is where I have changed my mind. There are no moral facts. Moral sentences have no truth-values. The world itself is silent, it just doesn’t speak to us in normative affairs — nothing in the physical universe tells us what makes an action a good action or a specific brain-state a desirable one. Sure, we all would like to know what a good neurophenomenological configuration really is, and how we should optimize our conscious minds in the future. But it looks like, in a more rigorous and serious sense, there is just no ethical knowledge to be had. We are alone. And if that is true, all we have to go by are the contingent moral intuitions evolution has hard-wired into our emotional self-model. If we choose to simply go by what feels good, then our future is easy to predict: It will be primitive hedonism and organized religion.

Darwin is the man, and like so many biologists, I have benefited from his prescient insights, handed to us 150 years ago. The logic of adaptation has been a guiding engine of my research and my view of life. In fact, it has been difficult to view the world through any other filter. I can still recall with great vividness the day I arrived in Cambridge, in June 1992, a few months before starting my job as an assistant professor at Harvard. I was standing on a street corner, waiting for a bus to arrive, and noticed a group of pigeons on the sidewalk. There were several males displaying, head bobbing and cooing, attempting to seduce the females. The females, however, were not paying attention. They were all turned, in Prussian solider formation, out toward the street, looking at the middle of the intersection where traffic was whizzing by. There, in the intersection, was one male pigeon, displaying his heart out. Was this guy insane? Hadn’t he read the handbook of natural selection. Dude, it’s about survival. Get out of the street!!!

Further reflection provided the solution to this apparently mutant, male pigeon. The logic of adaptation requires us to ask about the costs and benefits of behavior, trying to understand what the fitness payoffs might be. Even for behaviors that appear absurdly deleterious, there is often a benefit lurking. In the case of our apparently suicidal male pigeon, there was a benefit, and it was lurking in the females’ voyeurism, their rubber necking. The females were oriented toward this male, as opposed to the conservative guys on the sidewalk, because he was playing with danger, showing off, proving that even in the face of heavy traffic, he could fly like a butterfly and sting like a bee, jabbing and jiving like the great Muhammed Ali.

The theory comes from the evolutionary biologist Amotz Zahavi who proposed that even costly behaviors that challenge survival can evolve if they have payoffs to genetic fitness; these payoffs arrive in the currency of more matings, and ultimately, more babies. Our male pigeon was showing off his handicap. He was advertising to the females that even in the face of potential costs from Hummers and Beamers and Buses, he was still walking the walk and talking the talk. The females were hooked, mesmerized by this extraordinarily macho male. Handicaps evolve because they are honest indicators of fitness. And Zahavi’s theory represents the intellectual descendent of Darwin’s original proposal.

I must admit, however, that in recent years, I have made less use of Darwin’s adaptive logic. It is not because I think that the adaptive program has failed, or that it can’t continue to account for a wide variety of human and animal behavior. But with respect to questions of human and animal mind, and especially some of the unique products of the human mind — language, morality, music, mathematics — I have, well, changed my mind about the power of Darwinian reasoning.

Let me be clear about the claim here. I am not rejecting Darwin’s emphasis on comparative approaches, that is, the use of phylogenetic or historical data. I still practice this approach, contrasting the abilities of humans and animals in the service of understanding what is uniquely human and what is shared. And I still think our cognitive prowess evolved, and that the human brain and mind can be studied in some of the same ways that we study other bits of anatomy and behavior. But where I have lost the faith, so to speak, is in the power of the adaptive program to explain or predict particular design features of human thought.

Although it is certainly reasonable to say that language, morality and music have design features that are adaptive, that would enhance reproduction and survival, evidence for such claims is sorely missing. Further, for those who wish to argue that the evidence comes from the complexity of the behavior itself, and the absurdly low odds of constructing such complexity by chance, these arguments just don’t cut it with respect to explaining or predicting the intricacies of language, morality, music or many other domains of knowledge.

In fact, I would say that although Darwin’s theory has been around, and readily available for the taking for 150 years, it has not advanced the fields of linguistics, ethics, or mathematics. This is not to say that it can’t advance these fields. But unlike the areas of economic decision making, mate choice, and social relationships, where the adaptive program has fundamentally transformed our understanding, the same can not be said for linguistics, ethics, and mathematics. What has transformed these disciplines is our growing understanding of mechanism, that is, how the mind represents the world, how physiological processes generate these representations, and how the child grows these systems of knowledge.

Bidding Darwin adieu is not easy. My old friend has served me well. And perhaps one day he will again. Until then, farewell.

Mentors, paper referees and grant reviewers have warned me on occasion about scientific "fishing expeditions," the conduct of empirical research that does not test a specific hypothesis or is not guided by theory. Such "blind empiricism" was said to be unscientific, to waste time and produce useless data. Although I have never been completely convinced of the hazards of fishing, I now reject them outright, with a few reservations.

I'm not advocating the collection of random facts, but the use of broad-based descriptive studies to learn what to study and how to study it. Those who fish learn where the fish are, their species, number and habits. Without the guidance of preliminary descriptive studies, hypothesis testing can be inefficient and misguided. Hypothesis testing is a powerful means of rejecting error — of trimming the dead limbs from the scientific tree — but it does not generate hypotheses or signify which are worthy of test. I'll provide two examples from my experience.

In graduate school, I became intrigued with neuroembryology and wanted to introduce it to developmental psychology, a discipline that essentially starts at birth. My dissertation was a fishing expedition that described embryonic behavior and its neurophysiological mechanism. I was exploring uncharted waters and sought advice by observing the ultimate expert, the embryo. In this and related work, I discovered that prenatal movement is the product of seizure-like discharges in the spinal cord (not the brain), that the spinal discharges occurred spontaneously (not a response to sensory stimuli), that the function of  movement was to sculpt joints (not to shape postnatal behavior such walking), and to regulate the number of motorneurons. Remarkable! 

But decades later, this and similar work is largely unknown to developmental psychologists who have no category for it. The traditional psychological specialties of perception, learning, memory, motivation and the like, are not relevant during most of the prenatal period. The finding that embryos are profoundly unpsychological beings guided by unique developmental priorities and processes is not appreciated by theory-driven developmental psychologists. When the fishing expedition indicates that there is no appropriate spot in the scientific filing cabinet, it may be time to add another drawer. 

Years later and unrepentant, I embarked on a new fishing expedition, this time in pursuit of the human universal of laughter — what it is, when we do it, and what it means. In the spirit of my embryonic research, I wanted the expert to define my agenda—a laughing person. Explorations about research funding with administrators at a federal agency were unpromising. One linguist patiently explained that my project "had no obvious implications for any of the major theoretical issues in linguistics."  Another, a speech scientist, noted that "laughter isn't speech, and therefore had no relevance to my agency's mission." 

Ultimately, this atheoretical and largely descriptive work provided many surprises and counterintuitive findings. For example, laughter, like crying, is not consciously controlled, contrary to literature suggesting that we speak ha-ha as we would choose a word in speech. Most laughter is not a response to humor. Laughter and speech are controlled by different brain mechanisms, with speech dominating laughter. Contagious laughter is the product of neurologically programmed social behavior. Contrasts between chimpanzee and human laughter reveal why chimpanzees can't talk (inadequate breath control), and the evolutionary event necessary for the selection for human speech (bipedality).

Whether embryonic behavior or laughter, fishing expeditions guided me down the appropriate empirical path, provided unanticipated insights, and prevented flights of theoretical fancy. Contrary to lifelong advice, when planning a new research project, I always start by going fishing.

For most of my life I viewed any notion of the "soul" a fanciful religious invention. I agreed with the view of the late Nobel Laureate Francis Crick who in his book The Astonishing Hypothesis claimed "A modern neurobiologist sees no need for the religious concept of a soul to explain the behavior of humans and other animals." But is the idea of a soul really so crazy and beyond the limits of scientific reason? 

From the standpoint of neuroscience, it is easy to make the claim that Descartes is simply wrong about the separateness of brain and mind. The plain fact is that there is no scientific evidence that a self, an individual mind, or a soul could exist without a physical brain. However, there are persisting reasons why the self and the mind do not appear to be identical with, or entirely reducible to, the brain.

For example, in spite of the claims of Massachusetts physician Dr. Duncan MacDougall, who estimated through his experiments on dying humans that approximately 21 grams of matter — the presumed weight of the human soul — was lost upon death (The New York Times "Soul Has Weight, Physician Thinks" March 11, 1907), unlike the brain, the mind cannot be objectively observed, but only subjectively experienced. The subject that represents the "I" in the statement "I think therefore I am" cannot be directly observed, weighed, or measured. And the experiences of that self, its pains and pleasures, sights and sounds possess an objective reality only to the one who experiences them. In other words, as the philosopher John Searle puts it, the mind is "irreducibly first-person." 

On the other hand, although there are many perplexing properties about the brain, mind, and the self that remain to be scientifically explained — subjectivity among them — this does not mean that there must be an immaterial entity at work that explains these mysterious features. Nonetheless, I have come to believe that an individual consciousness represents an entity that is so personal and ontologically unique that it qualifies as something that we might as well call "a soul."

I am not suggesting that anything like a soul survives the death of the brain. Indeed, the link between the life of the brain and the life of the mind is irreducible, the one completely dependant upon the other. Indeed the danger of capturing the beauty and mystery of a personal consciousness and identity with the somewhat metaphorical designation "soul" is the tendency for the grandiose metaphor to obscure the actual accomplishments of the brain. The soul is not a "thing" independent of the living brain; it is part and parcel of it, its most remarkable feature, but nonetheless inextricably bound to its life and death.

When the phenomenon of "mirror neurons" that fire both when a specific action is perceived and when it is intended was first reported, I was impressed by the research but skeptical about its significance. Specifically, I doubted, and continue to doubt, that these circuits are specific adaptations for purposes of various higher mental functions. I saw mirror neurons as simple units in circuits that represent specific actions, oblivious as to whether they had been viewed when performed by someone else, or represented as the goal of one's own intended action (so-called reafference copy). Why have two separate representations of the same thing when one will do? Activity elsewhere in the brain represents who the agent is, self or another. I still think that this is the most economical interpretation. But from a broader perspective I have come to realize that mirror neurons are not only less than meets the eye but also more. Instead of being a specific specialization, they play their role as part of a fundamental design characteristic of the brain; that is, when percepts are activated, relevant intentions, memories and feelings automatically fall into place.

External event are "represented" by the patterns of neuronal activity that they engender in sensory cortex. These representations also incorporate the actions that the percepts potentially afford. This "enactive coding" or "common coding" of input implies a propensity in the observer's brain to imitate the actions of others (consciously or unconsciously). This propensity need not result in overt imitation. Prefrontal cortex is thought to hold these impulses to imitate in check. Nonetheless, the fact that these action circuits have been activated, lowers their threshold by subtle increments as the experience in question is repeated over and over again, and the relative loading of synaptic weights in brain circuitry become correspondingly adjusted. Mirror neurons exemplify this type of functioning, which extends far beyond individual circuits to all cell assemblies that can form representations,

That an individual is likely to act in the same ways that others act is seen in the documented benefit for sports training of watching experts perform. "Emotional contagion" occurs when someone witnesses the emotional expressions of another person and therefore experiences that mood state oneself. People's viewpoints can subtly and unconsciously converge when their patterns of neural activation match, in the total absence of argument or attempts at persuasion. When people entrain with each other in gatherings, crowds, assemblies and mobs, diverse individual views reduce into a unified group viewpoint. An extreme example of gradual convergence might be the "Stockholm Syndrome"; captives gradually adopt the worldview of their captors. In general, interacting with others makes one converge to their point of view (and vice versa). Much ink has been spilled on the topic of the lamentable limitations of human rationality. Here is one reason why.

People's views are surreptitiously shaped by their experiences, and rationality comes limping after, downgraded to rationalization. Once opinions are established, they engender corresponding anticipations. People actively seek those experiences that corroborate their own self-serving expectations. This may be why as we grow older, we become ever more like ourselves. Insights become consolidated and biases reinforced when one only pays attention to confirming evidence. Diverse mutually contradictory "firm convictions" are the result. Science does take account of the negative instance as well as the positive instance. It therefore has the potential to help us understand ourselves, and each other.

If I am correct in my changed views as to what mirror neurons stand for and how representation routinely merges perception, action, memory and affect into dynamic reciprocal interaction, these views would have a bearing on currently disputed issues. Whether an effect is due to the brain or the environment would be moot if environmental causes indeed become brain causes, as the impressionable brain resonates with changing circumstances. What we experience contributes mightily to what we are and what we become. An act of kindness has consequences for the beneficiary far beyond the immediate benefit. Acts of violence inculcate violence and contaminate the minds of those who stand by and watch. Not only our private experiences, but also the experiences that are imposed on us by the media, transform our predispositions, whether we want them to or not. The implications for child rearing are obvious, but the same implications apply beyond childhood to the end of personal time.

What people experience indeed changes their brain, for better and for worse. In turn, the changed brain changes what is experienced. Regardless of its apparent stability over time, the brain is in constant flux, and constantly remodels. Heraclitus was right: "You shall not go down twice to the same river". The river will not be the same, but for that matter, neither will you. We are never the same person twice. The past is etched into the neural network, biasing what the brain is and does in the present. William Faulkner recognized this: "The past is never dead. In fact, it's not even past".

I used to think that a modern, democratic society had to be a scientific society. After all, the scientific revolution and the American Revolution were forged in the same flames of the enlightenment. Naturally, I thought, a society that embraces the freedom of thought and expression of a democracy would also embrace science.

However, when I first started reporting on science, I quickly realized that science didn't spring up naturally in the fertile soil of the young American democracy. Americans were extraordinary innovators — wonderful tinkerers and engineers — but you can count the great 19th century American physicists on one hand and have two fingers left over. The United States owes its scientific tradition to aristocratic Europe's universities (and to its refugees), not to any native drive.

In fact, science clashes with the democratic ideal. Though it is meritocratic, it is practiced in the elite and effete world of academe, leaving the vast majority of citizens unable to contribute to it in any meaningful way. Science is about freedom of thought, yet at the same time it imposes a tyranny of ideas.

In a democracy, ideas are protected. It's the sacred right of a citizen to hold — and to disseminate — beliefs that the majority disagrees with, ideas that are abhorrent, ideas that are wrong. However, scientists are not free to be completely open minded; a scientist stops becoming a scientist if he clings to discredited notions. The basic scientific urge to falsify, to disprove, to discredit ideas clashes with the democratic drive to tolerate and protect them.

This is why even those politicians who accept evolution will never attack those politicians who don't; at least publicly, they cast evolutionary theory as a mere personal belief. Attempting to squelch creationism smacks of elitism and intolerance — it would be political suicide. Yet this is exactly what biologists are compelled to do; they exorcise falsehoods and drive them from the realm of public discourse.

We've been lucky that the transplant of science has flourished so beautifully on American soil. But I no longer take it for granted that this will continue; our democratic tendencies might get the best of us in the end.

What is the nature of mathematics? Becoming a mathematician in the 1960s, I swallowed hook, line, and sinker the Platonistic philosophy dominant at the time, that the objects of mathematics (the numbers, the geometric figures, the topological spaces, and so forth) had a form of existence in some abstract ("Platonic") realm. Their existence was independent of our existence as living, cognitive creatures, and searching for new mathematical knowledge was a process of explorative discovery not unlike geographic exploration or sending out probes to distant planets.

I now see mathematics as something entirely different, as the creation of the (collective) human mind. As such, mathematics says as much about we ourselves as it does about the external universe we inhabit. Mathematical facts are not eternal truths about the external universe, which held before we entered the picture and will endure long after we are gone. Rather, they are based on, and reflect, our interactions with that external environment.

This is not to say that mathematics is something we have freedom to invent. It's not like literature or music, where there are constraints on the form but writers and musicians exercise great creative freedom within those constraints. From the perspective of the individual human mathematician, mathematics is indeed a process of discovery. But what is being discovered is a product of the human (species)-environment interaction.

This view raises the fascinating possibility that other cognitive creatures in another part of the universe might have different mathematics. Of course, as a human, I cannot begin to imagine what that might mean. It would classify as "mathematics" only insofar as it amounted to that species analyzing the abstract structures that arose from their interactions with their environment.

This shift in philosophy has influenced the way I teach, in that I now stress social aspects of mathematics. But when I'm giving a specific lecture on, say, calculus or topology, my approach is entirely platonistic. We do our mathematics using a physical brain that evolved over hundreds of thousands of years by a process of natural selection to handle the physical and more recently the social environments in which our ancestors found themselves. As a result, the only way for the brain to actually do mathematics is to approach it "platonistically," treating mathematical abstractions as physical objects that exist.

A platonistic standpoint is essential to doing mathematics, just as Cartesian dualism is virtually impossible to dispense with in doing science or just plain communicating with one another ("one another"?). But ultimately, our mathematics is just that: our mathematics, not the universe's.

Reading and reporting on psychological science has changed my mind many times, leading me now to believe that 

• newborns are not the blank slates I once presumed,
• electroconvulsive therapy often alleviates intractable depression,
• economic growth has not improved our morale,
• the automatic unconscious mind dwarfs the controlled conscious mind,
• traumatic experiences rarely get repressed,
• personality is unrelated to birth order, 
• most folks have high self-esteem (which sometimes causes problems), 
• opposites do not attract,
• sexual orientation is a natural, enduring disposition (most clearly so for men), not a choice.

In this era of science-religion conflict, such revelations underscore our need for what science and religion jointly mandate: humility. Humility, I remind my student audience, is fundamental to the empirical spirit advocated long ago by Moses: "If a prophet speaks in the name of the Lord and what he says does not come true, then it is not the Lord's message." Ergo, if our or anyone's ideas survive being put to the test, so much the better for them. If they crash against a wall of evidence, it is time to rethink.

I have wondered why some authors claim that people rarely if ever change their mind. I have changed my mind many times. This could be because I have weak character, because I have no self-defining philosophy, or because I like change. Whatever the reason, I enjoy changing my mind. I have occasionally irritated colleagues with my seeming motto of 'If it ain't broke, break it.'

At the same time, I adhered to a value common in the day-to-day business of scientific research, namely, that changing one's mind is alright for little matters but is suspect when it comes to big questions. Take a theory that is compatible with either conclusion 'x' or conclusion 'y'. First you believed 'x'. Then you received new information and you believed 'y'. This is a little change. And it is a natural form of learning - a change in behavior resulting from exposure to new information.

But change your mind, say, about the general theory that you work with, at least in some fields, and you are looked upon as a kind of maverick, a person without proper research priorities, a pot-stirrer. Why is that, I wonder?

I think that the stigma against major mind changes in science results from what I call 'homeopathic bias' - scientific knowledge is built up bit by little bit as we move cumulatively towards the truth.

This bias can lead researchers to avoid concluding that their work undermines the dominant theory in any significant way. Non-homeopathic doses of criticism can be considered not merely inappropriate, but even arrogant - implying somehow that the researcher is superior to his or her colleagues, whose unifying conceptual scheme is now judged to be weaker than they have noticed or are been willing to concede.

So any scientist publishing an article or a book about a non-homeopathic mind-change could be committing a career-endangering act. But I love to read these kinds of books. They bother people. They bother me.

I changed my mind about this homeopathic bias. I think it is myopic for the most part. And I changed my mind on this because I changed my mind regarding the largest question of my field - where language comes from. This change taught me about the empirical issues that had led to my shift and about the forces that can hold science and scientists in check if we aren't aware of them.

I believed at one time that culture and language were largely independent. Yet there is a growing body of research that suggests the opposite - deep reflexes from culture are to be found in grammar.

But if culture can exercise major effects on grammar, then the theory I had committed most of my research career to - the theory that grammar is part of the human genome and that the variations in the grammars of the world's languages are largely insignificant, was dead wrong. There did not have to be a specific genetic capacity for grammar - the biological basis of grammar could also be the basis of gourmet cooking, of mathematical reasoning, and of medical advances - human reasoning.

Grammar had once seemed to me too complicated to derive from any general human cognitive properties. It appeared to cry out for a specialized component of the brain, or what some linguists call the language organ. But such an organ becomes implausible if we can show that it is not needed because there are other forces that can explain language as both ontogenetic and phlyogentic fact.

Many researchers have discussed the kinds of things that hunters and gatherers needed to talk about and how these influenced language evolution. Our ancestors had to talk about things and events, about relative quantities, and about the contents of the minds of their conspecifics, among other things. If you can't talk about things and what happens to them (events) or what they are like (states), you can't talk about anything. So all languages need verbs and nouns. But I have been convinced by the research of others, as well as my own, that if a language has these, then the basic skeleton of the grammar largely follows. The meanings of verbs require a certain number of nouns and those nouns plus the verb make simple sentences, ordered in logically restricted ways. Other permutations of this foundational grammar follow from culture, contextual prominence, and modification of nouns and verbs. There are other components to grammar, but not all that many. Put like this, as I began to see things, there really doesn't seem to be much need for grammar proper to be part of the human genome as it were. Perhaps there is even much less need for grammar as an independent entity than we might have once thought.

Not that long ago, I was under the impression that the basic problem of computer architecture had been solved. After all, computers got faster every year, and gradually whole new application domains emerged. There was constantly more memory available, and software hungrily consumed it. Each new computer had a bigger power supply, and more airflow to extract the increasing heat from the processor. 

Now, clock speeds aren't rising quite as quickly, and the progress that is made doesn't seem to help our computers start up or run any faster. The traditions of the computing industry, some going as far back as the first digital computers built by John von Neumann in the 1950s, are starting to grow obsolete. The slower computers seem to get faster, and the more deeply I understand the way things actually work, the more these problems become apparent to me. They really come to light when you think about a computer as a business.

Imagine if your company or organization had one fellow [the CPU] who sat in an isolated office, and refused to talk with anyone except his two most trusted deputies [the Northbridge and Southbridge], through which all the actual work the company does must be funneled. Because this one man — let's call him Bob — is so overloaded doing all the work of the entire company, he has several assistants [memory controllers] who remember everything for him. They do this through a complex system [virtual memory] of file cabinets of various sizes [physical memories], the organization over which they have strictly limited autonomy.

Because it is faster to find things in the smaller cabinets [RAM], where there is less to sift through, Bob asks them to put the most commonly used information there. But since he is constantly switching between different tasks, the assistants must swap in and out the files in the smaller cabinets with those in the larger ones whenever Bob works on something different ["thrashing"]. The largest file cabinet is humongous, and rotates slowly in front of a narrow slit [magnetic storage]. The assistant in charge of it must simply wait for the right folder to appear in front of him before passing it along [disk latency].

Any communication with customers must be handled through a team of receptionists [I/O controllers] who don't take the initiative to relay requests to one of Bob's deputies. When Bob needs customer input to continue on a difficult problem, he drops what he is doing to chase after his deputy to chase after a receptionist to chase down the customer, thus preventing work for other customers to be done in that time.

This model is clearly horrendous for numerous reasons. If any staff member goes out to lunch, the whole operation is likely to grind to a halt. Tasks that ought to be quite simple turn out to take a lot of time, since Bob must re-acquaint himself with the issues in question. If a spy gains Bob's trust, all is lost. The only way to make the model any better without giving up and starting over is to hire people who just do their work faster and spend more hours in the office. And yet, this is the way almost every computer in the world operates today.

It is much more sane to hire a large pool of individuals, and, depending on slow-changing customer needs, organize them into business units and assign them to customer accounts. Each person keeps track of his own small workload, and everyone can work on a separate task simultaneously. If the company suddenly acquires new customers, it can recruit more staff instead of forcing Bob to work overtime. If a certain customer demands more attention than was foreseen, more people can be devoted to the effort. And perhaps most importantly, collaboration with other businesses becomes far more meaningful than the highly coded, formal game of telephone that Bob must play with Frank, who works in a similar position at another corporation [a server]. Essentially, this is a business model problem as much as a computer science one.

These complaints only scratch the surface of the design flaws of today's computers. On an extremely low level, with voltages, charge, and transistors, energy is handled recklessly, causing tremendous heat, which would melt the parts in a matter of seconds were it not for the noisy cooling systems we find in most computers. And on a high level, software engineers have constructed a city of competing abstractions based on the fundamentally flawed "CPU" idea.

So I have changed my mind. I used to believe that computers were on the right track, but now I think the right thing to do is to move forward from our 1950s models to a ground-up, fundamentally distributed computing architecture. I started to use computers at 17 months of age and started programming them at 5, so I took the model for granted. But the present stagnation of perceptual computer performance, and the counter-intuitiveness of programming languages, led me to question what I was born into and wonder if there's a better way. Now I'm eager to help make it happen. When discontent changes your mind, that's innovation.

Do we need to understand consciousness to understand physics?  I used to answer "yes", thinking that we could never figure out the elusive "theory of everything" for our external physical reality without first understanding the distorting mental lens through which we perceive it.

After all, physical reality has turned out to be very different from how it seems, and I feel that most of our notions about it have turned out to be illusions. The world looks like it has three primary colors, but that number three tells us nothing about the world out there, merely something about our senses: that our retina has three kinds of cone cells. The world looks like it has impenetrably solid and stationary objects, but all except a quadrillionth of the volume of a rock is empty space between particles in restless schizophrenic vibration. The world feels like a three-dimensional stage where events unfold over time, but Einstein's work suggests that change is an illusion, time being merely the fourth dimension of an unchanging space-time that just is, never created and never destroyed, containing our cosmic history like a DVD contains a movie. The quantum world feels random, but Everett's work suggests that randomness too is an illusion, being simply the way our minds feel when cloned into diverging parallel universes.

The ultimate triumph of physics would be to start with a mathematical description of the world from the "bird's eye view" of a mathematician studying the equations (which are ideally simple enough to fit on her T-shirt) and to derive from them the "frog's eye view" of the world, the way her mind subjectively perceives it. However, there is also a third and intermediate "consensus view" of the world. From your subjectively perceived frog perspective, the world turns upside down when you stand on your head and disappears when you close your eyes, yet you subconsciously interpret your sensory inputs as though there is an external reality that is independent of your orientation, your location and your state of mind. It is striking that although this third view involves both censorship (like rejecting dreams), interpolation (as between eye-blinks) and extrapolation (like attributing existence to unseen cities) of your frog's eye view, independent observers nonetheless appear to share this consensus view. Although the frog's eye view looks black-and-white to a cat, iridescent to a bird seeing four primary colors, and still more different to a bee seeing polarized light, a bat using sonar, a blind person with keener touch and hearing, or the latest robotic vacuum cleaner, all agree on whether the door is open.

This reconstructed consensus view of the world that humans, cats, aliens and future robots would all agree on is not free from some of the above-mentioned shared illusions. However, it is by definition free from illusions that are unique to biological minds, and therefore decouples from the issue of how our human consciousness works. This is why I've changed my mind: although understanding the detailed nature of human consciousness is a fascinating challenge in its own right, it is notnecessary for a fundamental theory of physics, which need "only" derive the consensus view from its equations.

In other words, what Douglas Adams called "the ultimate question of life, the universe and everything" splits cleanly into two parts that can be tackled separately: the challenge for physics is deriving the consensus view from the bird's eye view, and the challenge for cognitive science is to derive the frog's eye view from the consensus view. These are two great challenges for the third millennium. They are each daunting in their own right, and I'm relieved that we need not solve them simultaneously.

Well, my biggest change of mind came only a few years ago. It was the outcome of a painful journey of self-discovery, where my wife and children stood behind me and made it possible, where I struggled with all my soul, and all my heart and all my might. But that had to do with my realizing that Broadway musicals are not cultural travesties, so it's a little tangential here. Instead I'll focus on science.
  
I'm both a neurobiologist and a primatologist, and I've changed my mind about plenty of things in both of these realms. But the most fundamental change is one that transcends either of those disciplines — this was my realizing that the most interesting and important things in the life sciences are not going to be explained with sheer reductionism. 

A specific change of mind concerned my work as a neurobiologist. 

This came about 15 years ago, and it challenged neurobiological dogma that I had learned in pre-school, namely that the adult brain does not make new neurons. This fact had always been a point of weird pride in the field — hey, the brain is SO fancy and amazing that its elements are irreplaceable, not like some dumb-ass simplistic liver that's so totally fungible that it can regrow itself. And what this fact also reinforced, in passing, was the dogma that the brain is set in stone very early on in life, that there's all sorts of things that can't be changed once a certain time-window had passed. 

Starting in the 1960's, a handful of crackpot scientists had been crying in the wilderness about how the adult brain does make new neurons. At best, their unorthodoxy was ignored; at worst, they were punished for it. But by the 1990's, it had become clear that they were right. And "adult neurogenesis" has turned into the hottest subject in the field — the brain makes new neurons, makes them under interesting circumstances, fails to under other interesting ones. 

The new neurons function, are integrated into circuits, might even be required for certain types of learning. And the phenomenon is a cornerstone of a new type of neurobiological chauvinism — part of the very complexity and magnificence of the brain is how it can rebuild itself in response to the world around it. 

So, I'll admit, this business about new neurons was a tough one for me to assimilate. I wasn't invested enough in the whole business to be in the crowd indignantly saying, No, this can't be true. Instead, I just tried to ignore it. "New neurons", christ, I can't deal with this, turn the page. And after an embarrassingly long time, enough evidence had piled up that I had to change my mind and decide that I needed to deal with it after all. And it's now one of the things that my lab studies.

The other change concerned my life as a primatologist, where I have been studying male baboons in East Africa. This also came in the early 90's. I study what social behavior has to do with health, and my shtick always was that if you want to know which baboons are going to be festering with stress-related disease, look at the low-ranking ones.  Rank is physiological destiny, and if you have a choice in the matter, you want to win some critical fights and become a dominant male, because you'll be healthier. And my change of mind involved two pieces.

The first was realizing, from my own data and that of others, that being dominant has far less to do with winning fights than with social intelligence and impulse control. The other was realizing that while health has something to do with social rank, it has far more to do with personality and social affiliation — if you want to be a healthy baboon, don't be a socially isolated one. This particular shift has something to do with the accretion of new facts, new statistical techniques for analyzing data, blah blah. Probably most importantly, it has to do with the fact that I was once a hermetic 22-year old studying baboons and now, 30 years later, I've changed my mind about a lot of things in my own life.

Although I have changed my mind about several ideas and theories, my longest struggle has been with the concept of time.  The most obvious and universal aspect about reality, as we experience it, is that it is structured as a succession of moments, each of which comes into being, supplanting what was just present and is now past.  But, as soon as we describe nature in terms of mathematical equations, the present moment and the flow of time seem to disappear, and time becomes just a number, a reading on an instrument,  like any other.

Consequently, many philosophers and physicists argue that time is an illusion, that reality consists of the whole four dimensional history of the universe, as represented in Einstein’s theory of general relativity.  Some, like Julian Barbour, go further and argue that, when quantum theory is unified with gravity,  time disappears completely.  The world is just a vast collection of moments which are represented by the "wave-function  of the universe."  Time not real, it is just an "emergent quantity" that is helpful to organize our observations of the universe when it is big and complex.

Other physicists argue that aspects of time are real, such as the relationships of causality, that record which events were the necessary causes of others. Penrose, Sorkin and Markopoulou have proposed models of quantum spacetime in which everything real reduces to these relationships of causality.

In my own  thinking, I first embraced the view that quantum reality is timeless.  In our work on loop quantum gravity we were able to take this idea more seriously than people before us could, because we could construct and study exact wave-functions of the universe. Carlo Rovelli , Bianca Dittrich and others worked out in detail how time would "emerge" from the study of the question of what quantities of the theory are observable.

But, somehow, the more this view was worked out in detail the less I was convinced. This was partly due to technical challenges in realizing the emergence of time, and partly because some naïve part of me could never understand conceptually how the basic experience of the passage of time could emerge from a world without time.

So in the late 90s I embraced the view that time,  as causality,  is real. This fit best the next stage of development of loop quantum gravity, which was based on quantum spacetime histories.    However,  even as we continued to make  progress on the technical side of these studies,  I found myself worrying  that the present moment and the flow of time were still nowhere represented.  And I had another motivation, which was to make sense of the idea that laws of nature could evolve in time.

Back in the early 90s I had formulated a view of laws evolving on a landscape of theories along with the universe they govern.  This had been initially ignored, but in the last few years there has been much study of dynamics on landscapes of theories. Most of these are framed in the timeless language of the "wavefunction  of the universe," in contrast to my original presentation, in which theories evolved in real time. As these studies progressed, it became clear that only those in which time played a role could generate  testable predictions — and this made me want  to think more deeply about time.

It is becoming clear to me that the mystery of the nature of time is connected with other fundamental questions such as the nature of truth in mathematics and whether there must be timeless laws of nature. Rather than being an illusion, time may be the only aspect of our present understanding of nature that is not temporary and emergent.

When I look at something, when I talk to somebody, when I write a few sentences about "what I have changed my mind about and why", the neuronal network in my brain changes all the time and there are even structural changes in the brain. Why is it that these changes don't come to mind all the time but remain subthreshold?  Certainly, if everything would come to mind what goes on in the brain, and if there would not be an efficient mechanism of informational garbage disposal, we would end up in mental chaos (which sometimes happens in unfortunate cases with neuronal dysfunctioning). It is only sometimes that certain events produce so much neuronal energy and catch so much attention that a conscious representation is made possible.

As most neuronal information processing remains in mental darkness, i.e. happens on an implicit level, it is in my view impossible to make a clear statement why somebody changed his or her mind about something. If somebody gives an explicit reason for having changed the mind about something, I am very suspicious. As "it thinks" all the time in my brain, and as these processes are beyond voluntary control, I am much less transparent to myself as I might want, and this is true for everybody. Thus, I cannot give a good reason why I changed my mind about a strong hypothesis or even belief or perhaps a prejudice in my scientific work which I had until several years ago.

A sentence of Ludwig Wittgenstein from his Tractatus Logico-Philosophicus (5.6) was like a dogma for me: "Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt. — The limits of my language signify the limits of my world " (my translation). Now I react to this sentence with an emphatic "No!".

As a neuroscientist I have to stay away from the language trap. In our research we are easily misguided by words. Without too much thinking we are referring to "consciousness", to "free will", to "thoughts", to "attention", to the "self", etc, and we give an ontological status to these terms. Some people even start to look at the potential site of consciousness or of free will in the brain, or some people ask the "what is ..." question that never can find an answer. The prototypical "what is ..." question was formulated 1600 years ago by Augustinus who said in the 11th book of his Confessions: "Quid est ergo tempus? Si nemo ex me quaerat scio, si quaerenti explicare velim nescio. — What is time? If nobody asks me, I know it, but if I have to explain it to somebody, I don't know it" (my translation).

Interestingly, Augustinus made a nice categorical mistake by referring to "knowing" at first on an implicit, and second on an explicit level. This categorical mistake is still with us when we ask questions like: "What is consciousness, free will,..."; one knows, but one does not. As neuroscientists we have to focus on processes in the brain which rarely or perhaps never map directly onto such terms as we use them. Complexity reduction in brains is necessary and it happens all the time, but the goal of this reductive process is not such terms, that might be useful for our communication, but efficient action. This is what I think today, but why I came to this conclusion I don't know; it was probably several reasons that finally resulted in a shift of mind. i.e. overcoming Wittgenstein's straitjacket.

When asked why all of her marriages failed, anthropologist Margaret Mead apparently replied, "I beg your pardon, I have had three marriages and none of them was a failure."  There are many people like Mead.  Some 90% of Americans marry by middle age.  And when I looked at United Nations data on 97 other societies, I found that more than 90% of men and women eventually wed in the vast majority of these cultures, too.  Moreover, most human beings around the world marry one person at a time: monogamy.  Yet, almost everywhere people have devised social or legal means to untie the knot.  And where they can divorce — and remarry — many do. 

So I had long suspected this human habit of "serial monogamy" had evolved for some biological purpose.  Planned obsolescence of the pairbond?  Perhaps the mythological "seven-year itch" evolved millions of years ago to enable a bonded pair to rear two children through infancy together.  If each departed after about seven years to seek "fresh features," as poet Lord Byron put it, both would have ostensibly reproduced themselves and both could breed again — creating more genetic variety in their young. 

So I began to cull divorce data on 58 societies collected since 1947 by the Statistical Office of the United Nations.  My mission: to prove that the "seven year itch" was a worldwide biological phenomenon associated in some way with rearing young.  

Not to be.  My intellectual transformation came while I was pouring over these divorce statistics in a rambling cottage, a shack really, on the Massachusetts coast one August morning.  I regularly got up around 5:30, went to a tiny desk that overlooked the deep woods, and poured over the pages I had Xeroxed from the United Nations Demographic Yearbooks.  But in country after country, and decade after decade, divorces tended to peak (the divorce mode) during and around the fourth year of marriage.  There were variations, of course.  Americans tended to divorce between the second and third year of marriage, for example.  Interestingly, this corresponds with the normal duration of intense, early stage, romantic love — often about 18 months to 3 years.  Indeed, in a 2007 Harris poll, 47% of American respondents said they would depart an unhappy marriage when the romance wore off, unless they had conceived a child.

Nevertheless, there was no denying it:  Among these hundreds of millions of people from vastly different cultures, three patterns kept emerging.  Divorces regularly peaked during and around the fourth year after wedding.  Divorces peaked among couples in their late twenties.  And the more children a couple had, the less likely they were to divorce: some 39% of worldwide divorces occurred among couples with no dependent children; 26% occurred among those with one child; 19% occurred among couples with two children; and 7% of divorces occurred among couples with three young. 

I was so disappointed.  I mulled about this endlessly.  My friend used to wave his hand over my face, saying, "Earth to Helen; earth to Helen."  Why do so many men and women divorce during and around the 4-year mark; at the height of their reproductive years; and often with a single child?  It seemed like such an unstable reproductive strategy.  Then suddenly I got that "ah-ha" moment:  Women in hunting and gathering societies breastfeed around the clock, eat a low-fat diet and get a lot of exercise — habits that tend to inhibit ovulation.  As a result, they regularly space their children about four years apart.  Thus, the modern duration of many marriages—about four years—conforms to the traditional period of human birth spacing, four years. 

Perhaps human parental bonds originally evolved to last only long enough to raise a single child through infancy, about four years, unless a second infant was conceived.  By age five, a youngster could be reared by mother and a host of relatives. Equally important, both parents could choose a new partner and bear more varied young.

My new theory fit nicely with data on other species.  Only about three percent of mammals form a pairbond to rear their young.  Take foxes.  The vixen's milk is low in fat and protein; she must feed her kits constantly; and she will starve unless the dog fox brings her food.  So foxes pair in February and rear their young together.  But when the kits leave the den in mid summer, the pairbond breaks up.  Among foxes, the partnership lasts only through the breeding season.  This pattern is common in birds.  Among the more than 8,000 avian species, some 90% form a pairbond to rear their young.  But most do not pair for life. A male and female robin, for example, form a bond in the early spring and rear one or more broods together.  But when the last of the fledgling fly away, the pairbond breaks up.  

Like pair-bonding in many other creatures, humans have probably inherited a tendency to love and love again—to create more genetic variety in our young.  We aren't puppets on a string of DNA, of course.  Today some 57% of American marriages last for life.  But deep in the human spirit is a restlessness in long relationships, born of a time long gone, as poet John Dryden put it, "when wild in wood the noble savage ran."

One of the big problems in physics — perhaps the biggest! — is figuring out how our two current best theories fit together. On the one hand we have the Standard Model, which tries to explain all the forces except gravity, and takes quantum mechanics into account.  On the other hand we have General Relativity, which tries to explain gravity, and does not take quantum mechanics into account. Both theories seem to be more or less on the right track — but until we somehow fit them together, or completely discard one or both, our picture of the world will be deeply schizophrenic.

It seems plausible that as a step in the right direction we should figure out a theory of gravity that takes quantum mechanics into account, but reduces to General Relativity when we ignore quantum effects (which should be small in many situations). This is what people mean by "quantum gravity" — the quest for such a theory.

The most popular approach to quantum gravity is string theory.  Despite decades of hard work by many very smart people, it's far from clear that this theory is successful. It's made no predictions that have been confirmed by experiment.  In fact, it's made few predictions that we have any hope of testing anytime soon!  Finding certain sorts of particles at the big new particle accelerator near Geneva would count as partial confirmation, but string theory says very little about the details of what we should expect. In fact, thanks to the vast "landscape" of string theory models that researchers are uncovering, it keeps getting harder to squeeze specific predictions out of this theory.

When I was a postdoc, back in the 1980s, I decided I wanted to work on quantum gravity. The appeal of this big puzzle seemed irresistible.  String theory was very popular back then, but I was skeptical of it.  I became excited when I learned of an alternative approach pioneered by Ashtekar, Rovelli and Smolin, called loop quantum gravity.

Loop quantum gravity was less ambitious than string theory. Instead of a "theory of everything", it only sought to be a theory of something: namely, a theory of quantum gravity.

So, I jumped aboard this train, and for about a decade I was very happy with the progress we were making. A beautiful picture emerged, in which spacetime resembles a random "foam" at very short distance scales, following the laws of quantum mechanics.

We can write down lots of theories of this general sort. However, we have never yet found one for which we can show that General Relativity emerges as a good approximation at large distance scales — the quantum soap suds approximating a smooth surface when viewed from afar, as it were.

I helped my colleagues Dan Christensen and Greg Egan do a lot of computer simulations to study this problem. Most of our results went completely against what everyone had expected.  But worse, the more work we did, the more I realized I didn't know what questions we should be asking!  It's hard to know what to compute to check that a quantum foam is doing its best to mimic General Relativity.

Around this time, string theorists took note of loop quantum gravity people and other critics — in part thanks to Peter Woit's blog, his bookNot Even Wrong, and Lee Smolin's book The Trouble with Physics.  String theorists weren't used to criticism like this.  A kind of "string-loop war" began.  There was a lot of pressure for physicists to take sides for one theory or the other. Tempers ran high.

Jaron Lanier put it this way: "One gets the impression that some physicists have gone for so long without any experimental data that might resolve the quantum-gravity debates that they are going a little crazy."  But even more depressing was that as this debate raged on, cosmologists were making wonderful discoveries left and right, getting precise data about dark energy, dark matter and inflation.  None of this data could resolve the string-loop war! Why?  Because neither of the contending theories could make predictions about the numbers the cosmologists were measuring! Both theories were too flexible.

I realized I didn't have enough confidence in either theory to engage in these heated debates.  I also realized that there were other questions to work on: questions where I could actually tell when I was on the right track, questions where researchers cooperate more and fight less.  So, I eventually decided to quit working on quantum gravity.

It was very painful to do this, since quantum gravity had been my holy grail for decades.  After you've convinced yourself that some problem is the one you want to spend your life working on, it's hard to change your mind.  But when I finally did, it was tremendously liberating.

I wouldn't urge anyone else to quit working on quantum gravity. Someday, someone is going to make real progress.  When this happens, I may even rejoin the subject.  But for now, I'm thinking about other things.  And, I'm making more real progress understanding the universe than I ever did before.

In the last few years I have changed my mind about nuclear power. I used to believe that expanding nuclear power was too risky. Now I believe that the risks of climate change are much greater than the risks of nuclear power. As a result we need to move urgently toward a new generation of nuclear reactors.  

What led to the change of view? First I came to believe that the likelihood of major climate related catastrophes was increasing rapidly and that they were likely to occur much sooner than the simple  linear models of the IPCC indicated. My analysis developed as a result of work we did for the defense and intelligence community on the national security implications of climate change. Many regions of the Earth are likely to experience an increasing frequency of extreme weather events. These catastrophic events include megastorms, super tornados, torrential rains and floods, extended droughts, ecosystem disruptions all added to steadily rising sea levels. It also became clear that human induced climate change is ever more at the causal center of the story.

Research by climatologists like William Ruddiman indicate that the climate is more sensitive to changes in human societies ranging from agricultural practices like forest clearing and  irrigated rice growing to major plagues to the use of fossil fuels. Human societies have often gone to war as a result of the ecological exhaustion of their local environments. So it becomes an issue of war and peace. Will Vietnam simply roll over and die when the Chinese dam what remains of the trickle of the Mekong as an extended drought develops at is source in the Tibetan highlands?

 Even allowing for much greater efficiency and a huge expansion of renewable energy, the real fuel of the future is coal, especially in the US, China and India. if all three go ahead with their current plans on building coal fired electric generating plants then that alone will over the next two decades double all the CO2 that human kind has put into the atmosphere since the industrial revolution began more than two hundred years ago. And the only meaningful alternative to coal is nuclear power. It is true that we can hope that our ability to capture the CO2 from coal burning and sequester it in various ways will grow, but it will take a decade or more before that technology reaches commercial maturity.

At the same time I also came to believe that risks of  nuclear power are less than we feared. That shift began with a trip to visit the proposed nuclear waste depository at Yucca Mountain in Nevada. A number ofEdge folk went including Stewart Brand, Kevin Kelly, Danny Hillis, and Pierre Omidyar. When it became clear that very long term storage of waste (e.g. 10,000 to 250,000 years) is a silly idea and not meaningfully realistic we began to question many of the assumptions about the future of nuclear power. The right answer to nuclear waste is temporary storage for perhaps decades and then recycling the fuel as much of the world already does, not sticking it underground for millennia. We will likely need the fuel we can extract from the waste.

There are emerging technologies for both nuclear power and waste reprocessing that will reduce safety risk, the amount of waste and most especially the risk of nuclear weapons proliferation as the new fuel cycle produces no plutonium, the offending substance of concern. And the economics are increasingly favorable as the French have demonstrated for decades. The average French citizen produces 70% less CO2 than the average American as a result. We have also learned that the long term consequences of the worst nuclear accident in history, Chernobyl were much less than feared.

So the conclusion is that the risks of climate change are far greater than the risks of nuclear power. Furthermore, human skill and knowledge in managing a nuclear system are only likely to grow with time. While the risks of climate change will grow as billions more people get rich and change the face of the planet with their demands for more stuff. Nuclear power is the only source of electricity that we can now see that is likely to enable the next three or four billion who want what we all have to get what they want without radically changing the climate of the Earth.

Most cosmologists would say the answer is "inflation," and, until recently, I would have been among them. But "facts have changed my mind" — and I now feel compelled to seek a new explanation that may or may not incorporate inflation. 

The idea always seemed incredibly simple. Inflation is a period of rapid accelerated expansion that can transform the chaos emerging from the big bang into the smooth, flat homogeny observed by astronomers. If one likens the conditions following the bang to a wrinkled and twisted sheet of perfectly elastic rubber, then inflation corresponds to stretching the sheet at faster-than-light speeds until no vestige of its initial state remains. The "inflationary energy" driving the accelerated expansion then decays into the matter and radiation seen today and the stretching slows to a modest pace that allows the matter to condense into atoms, molecules, dust, planets, stars and galaxies. 

I would describe this version as the "classical view" of inflation in two senses. First, this is the historic picture of inflation first introduced and now appearing in most popular descriptions. Second, this picture is founded on the laws of classical physics, assuming quantum physics plays a minor role. Unfortunately, this classical view is dead wrong. Quantum physics turns out to play an absolutely dominant role in shaping the inflationary universe. In fact, inflation amplifies the randomness inherent in quantum physics to produce an universe that is random and unpredictable. 

This realization has come slowly. Ironically, the role of quantum physics was believed to be a boon to the inflationary paradigm when it was first considered twenty-five years ago by several theorists, including myself. The classical picture of inflation could not be strictly true, we recognized, or else the universe would be so smooth after inflation that galaxies and other large-scale structures would never form. However, inflation ends through the quantum decay of inflationary energy into matter and radiation. The quantum decay is analogous to the decay of radioactive uranium, in which there is some mean rate of decay but inherent unpredictability as to when any particular uranium nucleus will decay. Long after most uranium nuclei have decayed, there remain some nuclei that have yet to fission.

Similarly, inflationary energy decays at slightly different times in different places, leading to spatial variations in the temperature and matter density after inflation ends. The "average" statistical pattern appears to agree beautifully with the pattern of microwave background radiation emanating from the earliest stages of the universe and to produce just the pattern of non-uniformities needed to explain the evolution and distribution of galaxies. The agreement between theoretical calculation and observations is a celebrated triumph of the inflationary picture. 

But is this really a triumph? Only if the classical view were correct. In the quantum view, it makes no sense to talk about an "average" pattern. The problem is that, as in the case of uranium nuclei, there always remain some regions of space in which the inflationary energy has not yet decayed into matter and radiation at all. Although one might have guessed the undecayed regions are rare, they expand so much faster than those that have decayed that they soon overtake the volume of the universe. The patches where inflationary energy has decayed and galaxies and stars have evolved become the oddity — rare pockets surrounded by space that continues to inflate away.

The process repeats itself over and over, with the number of pockets and the volume of surrounding space increasing from moment to moment. Due to random quantum fluctuations, pockets with all kinds of properties are produced — some flat, but some curved; some with variations in temperature and density like what we observe, but some not; some with forces and physical laws like those we experience, but some with different laws. The alarming result is that there are an infinite number of pockets of each type and, despite over a decade of attempts to avoid the situation, no mathematical way of deciding which is more probable has been shown to exist.

Curiously, this unpredictable "quantum view" of inflation has not yet found its way into the consciousness of many astronomers working in the field, let alone the greater scientific community or the public at large.

One often reads that recent measurements of the cosmic microwave background or the large-scale structure of the universe have verified a prediction of inflation. This invariably refers to a prediction based on the naïve classical view. But if the measurements ever come out differently, this could not rule out inflation. According to the quantum view, there are invariably pockets with matching properties.

And what of the theorists who have been developing the inflationary theory for the last twenty-five years? Some, like me, have been in denial, harboring the hope that a way can be found to tame the quantum effects and restore the classical view. Others have embraced the idea that cosmology may be inherently unpredictable, although this group is also vociferous in pointing how observations agree with the (classical) predictions of inflation.

Speaking for myself, it may have taken me longer to accept its quantum nature than it should have, but, now that facts have changed my mind, I cannot go back again. Inflation does not explain the structure of the universe. Perhaps some enhancement can explain why the classical view works so well, but then it will be that enhancement rather than inflation itself that explains the structure of the universe. Or maybe the answer lies beyond the big bang. Some of us are considering the possibility that the evolution of the universe is cyclic and that the structure was set by events that occurred before the big bang. One of the draws of this picture is that quantum physics does not play the same dominant role, and there is no escaping its predictions of the uniformity, flatness and structure of the universe.

Until I was twenty I was sure there was a being who could see everything I did and who didn't like most of it. He seemed to care about minute aspects of my life, like on what day of the week I ate a piece of meat. And yet, he let earthquakes and mudslides take out whole communities, apparently ignoring the saints among them who ate their meat on the assigned days.  Eventually, I realized that I didn't believe there was such a being. It didn't seem reasonable. And I assumed that I was an atheist. 

As I understood the word, it meant that I was someone who didn't believe in a God; I was without a God. I didn't broadcast this in public because I noticed that people who do believe in a god get upset to hear that others don't. (Why this is so is one of the most pressing of human questions, and I wish a few of the bright people in this conversation would try to answer it through research.) 

But, slowly I realized that in the popular mind the word atheist was coming to mean something more: a statement that there couldn't be a God. God was, in this formulation, not possible, and this was something that could be proved. But I had been changed by eleven years of interviewing six or seven hundred scientists around the world on the television program Scientific American Frontiers. And that change was reflected in how I would now identify myself. 

The most striking thing about the scientists I met was their complete dedication to evidence. It reminded me of the wonderfully plainspoken words of Richard Feynman who felt it was better not to know than to know something that was wrong. The problem for me was that just as I couldn't find any evidence that there was a god, I couldn't find any that there wasn't a god. I would have to call myself an agnostic. At first, this seemed a little wimpy, but after a while I began to hope it might be an example of Feynman's heroic willingness to accept, even glory in, uncertainty. 

I still don't like the word agnostic. It's too fancy. I'm simply not a believer. But, as simple as this notion is, it confuses some people. Someone wrote a Wikipedia entry about me, identifying me as an atheist because I'd said in a book I wrote that I wasn't a believer. I guess in a world uncomfortable with uncertainty, an unbeliever must be an atheist, and possibly an infidel. This gets us back to that most pressing of human questions: why do people worry so much about other people's holding beliefs other than their own? This is the question that makes the subject over which I changed my mind something of global importance, and not just a personal, semantic dalliance.

Do our beliefs identify us the way our language, foods and customs do? Is this why people who think the universe chugs along on its own are as repellent to some as people who eat live monkey brains are to others? Are we saying, you threaten my identity with your infidelity to my beliefs? You're trying to kill me with your thoughts, so I'll get you first with this stone? And, if so, is this really something that can be resolved through reasonable discourse? 

Maybe this is an even more difficult problem; one that's written in the letters that spell out our DNA. Why is the belief in God and Gods so ubiquitous? Does belief in a higher power confer some slight health benefit, and has natural selection favored those who are genetically inclined to believe in such a power — and is that why so many of us are inclined to believe? (Whether or not a God actually exists, the tendency to believe we'll be saved might give us the strength to escape sickness and disaster and live the extra few minutes it takes to replicate ourselves.)

These are wild speculations, of course, and they're probably based on a desperate belief I once had that we could one day understand ourselves. 

But, I might have changed my mind on that one, too.

Some time ago I thought that rational, enlightened thinking would eventually eradicate irrational thinking and supernatural beliefs. How could it be otherwise? Scientists and enlightened people have facts and logical arguments on their side, whereas people 'on the other side' have only unprovable beliefs and bad reasoning. I guess I was wrong, way wrong. Thirty years later, irrational thinking and supernatural beliefs are much stronger than they used to be, permeate ours and other societies and it does not seem they will go away any time soon. How is it possible? Shouldn't 'history' always move forward? What went wrong? What can we do to fix this backward movement toward the irrational?

The problem is that science has still a marginal role in our public discourse. Indeed, there are no science books on the New York Times100 Notable Books of the Year list, no science category in theEconomist Books of the Year 2007 and only Oliver Sacks in the New Yorker's list of Books From Our Pages.

Why does science have such a marginal role? I think there is more than one reason. First, scientists tend to confine themselves in well-defined, narrow boundaries. They tend not to claim any wisdom outside the confines of their specialties. By doing so, they marginalize themselves and make it difficult for science to have an impact on their society. It is high time for scientists to step up and claim wisdom outside their specialty.

There are also other ways, however, to have an impact on our society. For instance, by making some changes in scientific practices. In these days, scientific practices are dominated by the 'hypothesis testing' paradigm. While there is nothing wrong with hypothesis testing, it is definitely wrong to confine all science only to hypothesis testing. This approach precludes the study of complex, real world phenomena, the phenomena that are important to people outside academia. It is time to perform more broad-based descriptive studies on issues that are highly relevant to our society.

Another dominant practice in science (definitely in neuroscience, my own field) is to study phenomena from an atemporal perspective. Only the timeless seems to matter to most neuroscientists. Even time itself tends to be studied from this 'platonic ideal' perspective. I guess this approach stems from the general tendency of science to adopt the detached 'view from nowhere,' as Thomas Nagel puts is. If there is one major thing we have learned from modern science, however, is that there is no such thing, there is no 'view from nowhere.' It is time for scientists (especially neuroscientists) to commit to the study of the finite and temporal. The issues that matter 'here and now' are the issues that people relate to.

How should we do all this? One way of disseminating the scientific method in our public discourse is to use the tools and approaches of science to investigate issues that are salient to the general public. In neuroscience, we have now powerful tools that let us do this. We can study how people make decisions and form affiliations not from a timeless perspective, but from the perspective of what is salient 'here and now.' These are the kind of studies that naturally engage people. While they read about these studies, people are more likely to learn scientific facts (even the 'atemporal' ones) and to absorb the scientific method and reasoning. My hope is that by being exposed to and engaged by scientific facts, methods, and reasoning, people will eventually find it difficult to believe unprovable things.

Six years ago, I changed my mind about the benefit of being able to change my mind.

In 2002, Jane Ebert and I discovered that people are generally happier with decisions when they can't undo them. When subjects in our experiments were able to undo their decisions they tended to consider both the positive and negative features of the decisions they had made, but when they couldn't undo their decisions they tended to concentrate on the good features and ignore the bad. As such, they were more satisfied when they made irrevocable than revocable decisions. Ironically, subjects did not realize this would happen and strongly preferred to have the opportunity to change their minds.

Now up until this point I had always believed that love causes marriage. But these experiments suggested to me that marriage could also cause love. If you take data seriously you act on it, so when these results came in I went home and proposed to the woman I was living with. She said yes, and it turned out that the data were right: I love my wife more than I loved my girlfriend.

The willingness to change one's mind is a sign of intelligence, but the freedom to do so comes at a cost.

For most of my career, I believed that the bedrock of physical reality lay with the laws of physics — magnificent, immutable, transcendent, universal, infinitely-precise mathematical relationships that rule the universe with as sure a hand as that of any god. And I had orthdoxy on my side, for most of my physicist colleagues also believe that these perfect laws are the levitating superturtle that holds up the mighty edifice we call nature, as disclosed through science. About three years ago, however, it dawned on me that such laws are an extraordinary and unjustified idealization.

How can we be sure that the laws are infinitely precise? How do we know they are immutable, and apply without the slightest change from the beginning to the end of time? Furthermore, the laws themselves remain unexplained. Where do they come from? Why do they have the form that they do? Indeed, why do they exist at all? And if there are many possible such laws, then, as Stephen Hawking has expressed it, what is it that "breathes fire" into a particular set of laws and makes a universe for them to govern?

So I did a U turn and embraced the notion of laws as emergent with the universe rather than stamped on it from without like a maker's mark. The "inherent" laws I now espouse are not absolute and perfect, but are instrinsically fuzzy and flexible, although for almost all practical purposes we don't notice the tiny flaws.

Why did I change my mind? I am not content to merely accept the laws of physics as a brute fact. Rather, I want to explain the laws, or at least explain the form they have, as part of the scientific enterprise. One of the oddities about the laws is the well known fact that they are weirdly well-suited to the emergence of life in the universe. Had they been slightly different, chances are there would be no sentient beings around to discover them.

The fashionable explanation for this — that there is a multiplicity of laws in a multiplicity of parallel universes, with each set of laws fixed and perfect within its host universe — is a nice try, but still leaves a lot unexplained. And simply saying that the laws "just are" seems no better than declaring "God made them that way."

The orthodox view of perfect physical laws is a thinly-veiled vestige of monothesim, the reigning world view that prevailed at the birth of modern science. If we want to explain the laws, however, we have to abandon the theological legacy that the laws are fixed and absolute, and replace them with the notion that the states of the world and the laws that link them form a dynamic interdependent unity.

Growing up as a young proto-scientist, I was always strongly anti-establishmentarian, looking forward to overthrowing the System as our generation's new Galileo.  Now I spend a substantial fraction of my time explaining and defending the status quo to outsiders.  It's very depressing.

As an undergraduate astronomy I was involved in a novel and exciting test of Einstein's general relativity — measuring the precession of orbits, just like Mercury in the Solar System, but using massive eclipsing binary stars.  What made it truly exciting was that the data disagreed with the theory!  (Which they still do, by the way.)  How thrilling is it to have the chance to overthrow Einstein himself?  Of course there are more mundane explanations — the stars are tilted, or there is an invisible companion star perturbing their orbits, and these hypotheses were duly considered.  But I wasn't very patient with such boring possibilities — it was obvious to me that we had dealt a crushing blow to a cornerstone of modern physics, and the Establishment was just too hidebound to admit it.

Now I know better.  Physicists who are experts in the field tend to be skeptical of experimental claims that contradict general relativity, not because they are hopelessly encumbered by tradition, but because Einstein's theory has passed a startlingly diverse array of experimental tests.  Indeed, it turns out to be almost impossible to change general relativity in a way that would be important for those binary stars, but which would not have already shown up in the Solar System.  Experiments and theories don't exist in isolation — they form a tightly connected web, in which changes to any one piece tend to reverberate through various others.

So now I find myself cast as a defender of scientific orthodoxy — from classics like relativity and natural selection, to modern wrinkles like dark matter and dark energy.  In science, no orthodoxy is sacred, or above question — there should always be a healthy exploration of alternatives, and I have always enjoyed inventing new theories of gravity or cosmology, keeping in mind the variety of evidence in favor of the standard picture.  But there is also an unhealthy brand of skepticism, proceeding from ignorance rather than expertise, which insists that any consensus must flow from a reluctance to face up to the truth, rather than an appreciation of the evidence.  It's that kind of skepticism that keeps showing up in my email.  Unsolicited.

Heresy is more romantic than orthodoxy.  Nobody roots for Goliath, as Wilt Chamberlain was fond of saying.  But in science, ideas tend to grow into orthodoxy for good reasons.  They fit the data better than the alternatives.  Many casual heretics can't be bothered with all the detailed theoretical arguments and experimental tests that support the models they hope to overthrow — they have a feeling about how the universe should work, and are convinced that history will eventually vindicate them, just as it did Galileo.

What they fail to appreciate is that, scientifically speaking, Galileo overthrew the system from within.  He understood the reigning orthodoxy of his time better than anyone, so he was better able to see beyond it.  Our present theories are not complete, and nobody believes they are the final word on how Nature works.  But finding the precise way to make progress, to pinpoint the subtle shift of perspective that will illuminate a new way of looking at the world, will require an intimate familiarity with our current ideas, and a respectful appreciation of the evidence supporting them. 

Being a heretic can be fun; but being a successful heretic is mostly hard work.

I used to believe that we could understand psychology at different levels of analysis, and events at any one of the levels could be studied independently of events at the other levels. For example, one could study events at the level of the brain (and seek answers in terms of biological mechanisms), the level of the person (and seek answers in terms of the contents of thoughts, beliefs, knowledge, and so forth), or the level of the group (and seek answers in terms of social interactions). This approach seemed reasonable; the strategy of "divide and conquer" is a cornerstone in all of science, isn't it? In fact, virtually all introductory psychology textbooks are written as if events at the different levels are largely independent, with separate chapters (that only rarely include cross-references to each other) on the brain, perception, memory, personality, social psychology, and so on. 

I've changed my mind. I don't think it's possible to understand events at any one level of analysis without taking into account what occurs at other levels. In particular, I'm now convinced that at least some aspects of the structure and function of the brain can only be understood by situating the brain in a specific cultural context. I'm not simply saying that the brain has evolved to function in a specific type of environment (an idea that forms a mainstay of evolutionary psychology and some areas of computer vision, where statistics of the natural environment are used to guide processing). Rather, I'm saying that to understand how any specific brain functions, we need to understand how that person was raised, and currently functions, in the surrounding culture. 

Here's my line of reasoning. Let's begin with a fundamental fact: The genes, of which we have perhaps only some 30,000, cannot program us to function equally effectively in every possible environment. Hence, evolution has licensed the environment to set up and configure each individual's brain, so that it can work well in that context. For example, consider stereovision. We all know about stereo in audition; the sound from each of two loudspeakers has slightly different phases, so the listener's brain glues them together to provide the sense of an auditory panorama. Something similar is at work in vision. In stereovision, the slight disparity in the images that reach the two eyes are a cue for how far away objects are. If you're focused on an object directly in front of you, your eyes will converge slightly. Aside from the exact point of focus, the rest of the image will strike slightly different places on the two retinas (at the back of the eye, which converts light into neural impulses), and the brain uses the slight disparities to figure out how far away something is. 
            
There are two important points here. First, this stereo process — of computing depth on the basis of the disparities in where images strike the two retinas — depends on the distance between the eyes. And second, and this is absolutely critical, there's no way to know at the moment of conception how far apart a person's eyes are going to be, because that depends on bone growth — and bone growth depends partly on the mother's diet and partly on the infant's diet. 
            
So, given that bone growth depends partly on the environment, how could the genes set up stereovision circuits in the brain? What the genes did is really clever: Young children (peaking at about age 18 months) have more connections among neurons than do adults; in fact, until about eight years old, children have about twice as many neural connections as they do as adults. But only some of these connections provide useful information. For example, when the infant reaches, only the connections from some neurons will correctly guide reaching. The brain uses a process called pruning to get rid of the useless connections. The connections that turn out to work, with the distance between the eyes the infant happens to have, would not be the ones that would work if the mother did not have enough calcium, or the infant hadn't had enough of various dietary supplements. 
            
This is a really elegant solution to the problem that the genes can't know in advance how far apart the eyes will be. To cope with this problem, the genes overpopulate the brain, giving us options for different environments (where the distance between eyes and length of the arms are part of the brain's "environment," in this sense), and then the environment selects which connections are appropriate. In other words, the genes take advantage of the environment to configure the brain. 

This overpopulate-and-select mechanism is not limited to stereovision. In general, the environment sets up the brain (above and beyond any role it may have had in the evolution of the species), configuring it to work well in the world a person inhabits. And by environment I'm including everything outside the brain — including the social environment. For example, it's well known that children can learn multiple languages without an accent and with good grammar, if they are exposed to the language before puberty. But after puberty, it's very difficult to learn a second language so well. Similarly, when I first went to Japan, I was told not even to bother trying to bow, that there were something like a dozen different bows and I was always going to "bow with an accent" — and in my case the accent was so thick that it was impenetrable.  
            
The notion is that a variety of factors in our environment, including in our social environment, configure our brains. It's true for language, and I bet it's true for politeness as well as a raft of other kinds of phenomena. The genes result in a profusion of connections among neurons, which provide a playing field for the world to select and configure so that we fit the environment in which we inhabit. The world comes into our head, configuring us. The brain and its surrounding environment are not as separate as they might appear.  

This perspective leads me to wonder whether we can assume that the brains of people living in different cultures process information in precisely the same ways. Yes, people the world over have much in common (we are members of the same species, after all), but even small changes in the wiring may lead us to use the common machinery in different ways. If so, then people from different cultures may have unique perspectives on common problems, and be poised to make unique contributions toward solving such problems. 

Changing my mind about the relationship between events at different levels of analysis has led me to change fundamental beliefs. In particular, I now believe that understanding how the surrounding culture affects the brain may be of more than merely "academic interest."

At age 10 in 1950, one of the department stores had a pneumatic tube system for moving receipts and money from counters to the cashier's office. I loved this and tried to figure out how it worked The clerks in the store knew all about it. "Vacuum", they said, "Vacuum sucks the canisters, just like your mom's vacuum cleaner". But how does it work, I asked? "Vacuum", they said, "Vacuum, does it all". This was what adults called "an explanation"!

So I took apart my mom's Hoover vacuum cleaner to find out how it worked. There was an electric motor in there, which I had expected, but the only other thing in there was a fan! How could a fan produce a vacuum, and how could it suck?

We had a room fan and I looked at it more closely. I knew that it worked like the propeller of an airplane, but I'd never thought about how those worked. I picked up a board and moved it. This moved air just fine. So the blades of the propeller and the fan were just boards that the motor kept on moving to push air.

But what about the vacuum? I found that a sheet of paper would stick to the back of the fan. But why? I "knew" that air was supposed to be made up of particles too small to be seen. So it was clear why you got a gust of breeze by moving a board — you were knocking little particles one way and not another. But where did the sucking of the paper on the fan and in the vacuum cleaner come from?

Suddenly it occurred to me that the air particles must be already moving very quickly and bumping into each other. When the board or fan blades moved air particles away from the fan there were less near the fan and the already moving particles would have less to bump into and would thus move towards the fan. They didn't know about the fan, but they appeared to.

The "suck" of the vacuum cleaner was not a suck at all. What was happening is that things went into the vacuum cleaner because they were being "blown in" by the air particles' normal movement, which were not being opposed by the usual pressure of air particles inside the fan!

When my physiologist father came home that evening I exclaimed "Dad, the air particles must be moving at least a hundred miles an hour!". I told him what I'd found out and he looked in his physics book. In there was a formula to compute the speed of various air molecules at various temperatures. It turned out that at room temperature ordinary air molecules were moving much faster than I had guessed: more like 1500 miles an hour! This completely blew my mind!

Then I got worried because even small things were clearly not moving that fast going into the vacuum cleaner (nor in the pneumatic tubes). By putting my hand out the window of the car I could feel that the air was probably going into the vacuum cleaner closer to 50 or 60 miles an hour. Another conversation with my Dad led to two ideas (a) the fan was probably not very efficient at moving particles away, and (b) the particles themselves were going in every direction and bumping into each other (this is why it takes a while for perfume from an open bottle to be smelled across a room.

This experience was a big deal for me because I had thought one way using a metaphor and a story about "sucking", and then I suddenly thought just the opposite because of an experiment and non-story thinking. The world was not as it seemed! Or as most adults thought and claimed! I never trusted "just a story" again.

I have, falteringly and with various intermediary about-faces and caveats, changed my mind about human spaceflight. I am of the generation to have had its childhood imagination stoked by the sight of Apollo missions on the television — I can't put hand on heart and say I remember the Eagle landing, but I remember the sights of the moon relayed to our homes. I was fascinated by space and only through that, by way of the science fiction that a fascination with space inexorably led to, by science. And astronauts were what space was about.

I was not, as I grew older, uncritical of human spaceflight — I remember my anger at the Challenger explosion, my sense that if people were going to die, it should be for something grander than just another shuttle mission. But I was still struck by its romance, and by the way its romance touched some of the unlikeliest people. By all logic The Economist should have been, when I worked there, highly dubious about the aspirations of human spaceflight, as it is today. But the then editor would hear not a word against the undertaking, at least not against its principle. With some relief at this I became while the magazine's science editor a sort of critical apologist — critical of the human space programme there actually was, but sensitive to the possibility that a better space programme was possible.

I bought into, at least at some level, the argument that a joint US-Russian programme offered advantages in terms of aerospace employment in the former USSR. I bought into the argument that continuity of effort was needed — that so much would be lost if a programme was dismantled it might not be possible to reassemble it. I bought into the crucial safety-net argument — that it would not be possible to cancel the US programme anyway, so strong were the interests of the military industrial complex and so broad, if shallow, the support of the public. (Like the Powder River, a mile wide, an inch deep and rolling uphill all the way from Texas.) And I could see science it would offer that was unavailable by any other means.

Now, though, I can no longer find much to respect in those arguments. US Russian cooperation seems to have bought little benefit. The idea of continuous effort seems at best unproven — and indeed perhaps worth checking. Leaving a technology fallow for a few decades and coming back with new people, tools and mindsets is not such a bad idea. And at least one serious presidential candidate is talking about actually freezing the American programme, cancelling the shuttle without in the short term developing its successor. Whether Obama will get elected or be willing or able to carry through the idea remains to be seen — but if politicians are talking like this the "it will never happen so why worry" argument becomes far more suspect.

And the crucial idea (crucial to me) that human exploration of Mars might answer great questions about life in the universe no longer seems as plausible or as likely to pay off in my lifetime as once it did. I increasingly think that life in a Martian deep biosphere if there is any, will be related to earth life and teach us relatively little that's new. At the same time it will be fiendishly hard to reach without contamination. Mars continues to fascinate me — but it has ever less need of a putative future human presence in order to do so.

My excitement at the idea of life in the universe — excitement undoubtedly spurred by Apollo and the works of Clarke, Heinlein and Roddenberry that followed on from it in my education — is now more engaged with exoplanets, to which human spaceflight is entirely irrelevant (though post-human spaceflight may be a different kettle of lobsters). If we want to understand the depth of the various relations between life and planets, which is what I want to understand, it is by studying other planets with vibrant biospheres, as well as this one, that we will do so. A world with a spartan $100 billion moonbase but no ability to measure spectra and lightcurves from earthlike planets around distant stars is not the world for me.

In general, I try to avoid arguing from my own interests. But in this case it seems to me that all the other arguments against human spaceflight are so strong that to be against it merely meant realising that an atavistic part of me had failed to understand what those interests are. I'm interested in how life works on astronomical scales, and that interest has nothing to do, in the short term, with human spaceflight. And I see no reason beyond my own interests to suggest that it is something worth spending so much money on. It does not make the world a better place in any objective way that can be measured, or in any subjective way that compels respect.

It is possibly also the case that seeing human spaceflight reduced to a matter of suborobital hops for the rich, or even low earth orbit hotels, has hardened my heart further against it. I hope this is not a manifestation of the politics of envy, though I fear that in part it could be.

I have changed my mind about technology.

I used to take a dim view of technology. One should live one's life in a simple, low-tech fashion, I thought. No cell phone, keep off the computer, don't drive. No nukes, no remote control, no DVD, no TV. Walk, read, think — that was the proper path to follow.

What a fool I was! A dozen years ago or so, by some bizarre accident, I became a professor of Mechanical Engineering at MIT. I had never had any training, experience, or education in engineering. My sole claim to engineering expertise was some work on complex systems and a few designs for quantum computers. Quantum-mechanical engineering was in its early days then, however, and MIT needed a quantum mechanic. I was ready to answer the call.

It was not my fellow professors who converted me to technology, uber-techno-nerds though they were. Indeed, my colleagues in Mech. E. were by and large somewhat suspicious of me, justifiably so. I was wary of them in turn, as one often is of co-workers who are hugely more knowledgeable than one is oneself. (Outside of the Mechanical Engineering department, by contrast, I found large numbers of kindred souls: MIT was full of people whose quanta needed fixing, and as a certified quantum mechanic, I was glad to oblige.) No, it was not the brilliant technologists who filled the faculty lunchroom who changed my mind. Rather, it was the students who had come to have me teach them about engineering who taught me to value technology.

Your average MIT undergraduate is pretty technologically adept. In the old days, freshmen used to arrive MIT having disassembled and reassembled tractors and cars; slightly later on, they arrived having built ham radios and guitar amplifiers; more recently, freshmen and fresh women were showing up with a scary facility with computers. Nowadays, few of them have used a screwdriver (except maybe to install some more memory in their laptop), but they are eager to learn how robots work, and raring to build one themselves.

When I stepped into my first undergraduate classroom, a controls laboratory, I knew just about as little about how to build a robot as the nineteen and twenty year olds who were expectantly sitting, waiting for me to teach them how. I was terrified. Within a half an hour, the basis for my terror was confirmed. Not only did I know as little as the students, in many cases I knew significantly less: about of the quarter of the students knew demonstrably more about robotics than I, and were happy to display their knowledge. I emerged from the first lab session a sweaty mess, having managed to demonstrate my ignorance and incompetence in a startling variety of ways.

I emerged  from the second lab session a little cooler. There is no better way to learn, and learn fast, than to teach. Humility actually turns out to have its virtues, too. It turns out to be rather fun to admit one's ignorance, if that admission takes the form of an appeal to the knowledge of all assembled. In fact, it turned out that, either through my training in math and physics, or through a previous incarnation, I possessed more intuitive knowledge of control theory than I had any right to, given my lack of formal education on the subject. Finally, no student is more empowered than the one who has just correctly told her professor that he is wrong, and showed him why her solution is the right one.

In the end, the experience of teaching the technology that I did not know was one of the most intellectually powerful of my life. In my mental ferment of trying to learn the material faster and deeper than my students, I began to grasp concepts and ways of looking at the world, of whose existence I had no previous notion. One of the primary features of the lab was a set of analog computers, boxy things festooned with dials and plugs, and full of amplifiers, capacitors, and resistors, that were used to simulate, or construct an analog, of the motors and loads that we were trying to control. In my feverish attempt to understand analog computers, I constructed model for a quantum-mechanical analog computer that would operate at the level of individual atoms. This model resulted in one of my best scientific papers. In the end, scarily enough, my student evaluations gave me the highest possible marks for knowledge of the material taught.

And technology? Hey, it's not so bad. When it comes to walking in the rain, Goretex and fleece beat oilskin and wool hollow. If we're not going to swamp our world in greenhouse gases, we damn well better design dramatically more efficient cars and power plants. And if I could contribute to technology by designing and helping to build quantum computers and quantum communication systems, so much the better. Properly conceived and constructed technology does not hinder the simple life, but helps it.

OK. So I was wrong about technology. What's my next misconception? Religion? God forbid.

In public appearances about global warming, even these days, I often hear: "I don't believe in global warming" and I then typically get asked why I do "when all the evidence is not in". "Global warming is not about beliefs", I typically retort, "but an accumulation of evidence over decades so that we can now say the vast preponderance of evidence — and its consistency with basic climate theory — supports global warming as well established, not that all aspects are fully known, an impossibility in any complex systems science".

But it hasn't always been that way, especially for me at the outset of my career in 1971, when I co-authored a controversial paper calculating that cooling effects from a shroud of atmospheric dust and smoke — aerosols — from human emissions at a global scale appeared to dominate the opposing warming effect of the growing atmospheric concentrations of the greenhouse gas carbon dioxide. Measurements at the time showed both warming and cooling emissions were on the rise, so a calculation of the net balance was essential — though controlling the aerosols made sense with or without climate side effects since they posed — and still pose — serious health effects on vulnerable populations.  In fact for the latter reason laws to clean up the air in most rich countries were just getting negotiated about that time.

When I traveled the globe in the early 1970s to explain our calculations, what I slowly learned from those out there making measurements was that two facts had only recently come to light, and together they appeared to make me consider flipping sign from cooling to warming as the most likely climatic change direction from humans using the atmosphere as a free sewer to dump some of our volatile industrial and agricultural wastes.  These facts were that human-injected aerosols, which we assumed were global in scale in our cooling calculation — were in fact concentrated primarily in industrial regions and bio-mass burning areas of the globe — about 20% of the Earth's surface, whereas we already knew that CO2 emissions are global in extent and about half of the emitted CO2 lasts for a century or more in the air.

But there were new facts that were even more convincing: not only is CO2 an important human-emitted greenhouse gas, but so too were methane, nitrous oxide and chlorofluorocarbons (many of the latter gases now banned because they also deplete stratospheric ozone) , and that together with CO2, these other greenhouse gasses were an enhanced global set of warming factors. On the other hand, aerosols were primarily regional in extent and could not thus overcome the warming effects of the combined global scale greenhouse gases.

I was very proud to have published in the mid-1970s what was wrong with my early calculations well before the so-called "contrarians" — climate change deniers still all too prevalent even today — understood the issues, let alone incorporated these new facts into updated models to make more credible projections. Of course, today the dominance of warming over cooling agents is now well established in the climatology community, but our remaining inability to be very precise over how much warming the planet can expect to have to deal with is in large part still an uncertainty over the partially counteracting cooling effects of aerosols — enough to offset a significant, even if largely unknown, amount of the warming. So although we are very confident in the existence of human-caused warming in the past several decades from greenhouse gases, we are still are working hard to pin down much more precisely how much aerosols offset this warming. Facts on that offset still lag the critical need to estimate better our impacts on climate before they become potentially irreversible.

The sad part of this story is not about science, but the misinterpretation of it in the political world. I still have to endure polemical blogs from contrarian columnists and others about how, as one put it in a grand polemic: "Schneider is an environmentalist for all temperatures" — citing my early calculations. This famous columnist somehow forgot to bring up the later-corrected (by me) faulty assumptions, nor mention that the 1971 calculation was based on not-yet-gathered facts. Simply getting the sign wrong was cited, ipso facto in this blog, as somehow damning of my current credibility. 

Ironically, inside the scientific world, this switch of sign of projected effects is viewed as precisely what responsible scientists must do when the facts change. Not only did I change my mind, but published almost immediately what had changed and how that played out over time. Scientists have no crystal ball, but we do have modeling methods that are the closest approximation available. They can't give us truth, but they can tell us the logical consequences of explicit assumptions. Those who update their conclusions explicitly as facts evolve are much more likely to be a credible source than those who stick to old stories for political consistency. Two cheers for the scientific method!

I changed my mind about online community this year.

I co-edit a blog that attracts a large number of daily visitors, many of whom have something to say back to us about whatever we write or produce in video. When our audience was small in the early days, interacting was simple: we tacked a little href tag to an open comments thread at the end of each post: Link, Discuss. No moderation, no complication, come as you are, anonymity's fine. Every once in a while, a thread accumulated more noise than signal, but the balance mostly worked.

But then, the audience grew. Fast. And with that, grew the number of antisocial actors, "drive-by trolls," people for whom dialogue wasn't the point. It doesn't take many of them to ruin the experience for much larger numbers of participants acting in good faith.

Some of the more grotesque attacks were pointed at me, and the new experience of being on the receiving end of that much personally-directed nastiness was upsetting. I dreaded hitting the "publish" button on posts, because I knew what would now follow.

The noise on the blog grew, the interaction ceased to be fun for anyone, and with much regret, we removed the comments feature entirely.

I grew to believe that the easier it is to post a drive-by comment, and the easier it is to remain faceless, reputation-less, and real-world-less while doing so, the greater the volume of antisocial behavior that follows. I decided that no online community could remain civil after it grew too large, and gave up on that aspect of internet life.

My co-editors and I debated, we brainstormed, we observed other big sites that included some kind of community forum or comments feature. Some relied on voting systems to "score" whether a comment is of value — this felt clinical, cold, like grading what a friend says to you in conversation. Dialogue shouldn't be a beauty contest. Other sites used other automated systems to rank the relevance of a speech thread. None of this felt natural to us, or an effective way to prevent the toxic sludge buildup. So we stalled for years, and our blog remained more monologue than dialogue. That felt unnatural, too.

Finally, this year, we resurrected comments on the blog, with the one thing that did feel natural. Human hands.

We hired a community manager, and equipped our comments system with a secret weapon: the "disemvoweller." If someone's misbehaving, she can remove all the vowels from their screed with one click. The dialogue stays, but the misanthrope looks ridiculous, and the emotional sting is neutralized.

Now, once again, the balance mostly works. I still believe that there is no fully automated system capable of managing the complexities of online human interaction — no software fix I know of. But I'd underestimated the power of dedicated human attention.

Plucking one early weed from a bed of germinating seeds changes everything. Small actions by focused participants change the tone of the whole. It is possible to maintain big healthy gardens online. The solution isn't cheap, or easy, or hands-free. Few things of value are.

I have learned quantum mechanics as a young man, first from the book by Dirac, and then form a multitude of other excellent textbooks. The theory appeared bizarre and marvelous, but it made perfectly sense to me. The world, as Shakespeare put it, is "strange and admirable", but it is coherent. I could not understand why people remained unhappy with such a clear and rational theory. In particular, I could not understand why some people lost their time on a non-problem called the "interpretation of quantum mechanics".

I have remained of this opinion for many years. Then I moved to Pittsburgh, to work in the group of Ted Newman, great relativist and one of the most brilliant minds in the generation before mine. While there, the experiments made by the team of Alain Aspect Aspect at Orsay, in France, which confirmed spectacularly some of the strangest predictions of quantum mechanics, prompted a long period of discussion in our group. Basically, Ted claimed that quantum theory made no sense. I claimed that it does perfectly, since it is able to predict unambiguously the probability distribution of any conceivable observation.

Long time has passed, and I have changed my mind. Ted's arguments have finally convinced me: I was wrong, and he was right. I have slowly came to realize that in its most common textbook version, quantum mechanics makes sense as a theory of a small portion of the universe, a "system", only under the assumption that something else in the universe fails to obey quantum mechanics. Hence it becomes self contradictory, in its usual version, if we take it as a general description of all physical systems of the universe. Or, at least, there is still something key to understand, with respect to it.

This change of opinion has motivated me to start of a novel line of investigation, which I have called "relational quantum mechanics". It has also affected substantially my work in quantum gravity, taking me to consider a different sort of observable quantities as natural probes of quantum spacetime.

I am now sure that quantum theory has still much to tell us about the deep structure of the world. Unless I'll change my mind again, of course.

When reporters interviewed me in the 70's and 80's about the possibilities for Artificial Intelligence I would always say that we would have machines that are as smart as we are within my lifetime. It seemed a safe answer since no one could ever tell me I was wrong. But I no longer believe that will happen. One   reason is that  I am a lot older and we are barely closer to creating smart machines. 

I have not soured on AI. I still believe that we can create very intelligent machines. But I no longer believe that those machines will be like us. Perhaps it was the movies that led us to believe that we would have intelligent robots as companions. (I was certainly influenced early on by 2001.)  Certainly most AI researchers believed that creating machines that were our intellectual equals or better was a real possibility. Early AI workers sought out intelligent behaviors to focus on, like chess or problem solving, and tried to build machines that could equal human beings in those same endeavors. While this was an understandable approach it was, in retrospect, wrong-headed.     Chess playing is not really a typical intelligent human activity. Only some of us are good at it, and it seems to entail a level of cognitive processing that while impressive seems quite at odds with what makes humans smart. Chess players are methodical planners. Human beings are not.

Humans are constantly learning.  We spend years learning some seemingly simple stuff. Every new experience changes what we know and how we see the world. Getting reminded of our pervious experiences helps us process new experiences better than we did the time before. Doing that depends upon an unconscious indexing method that all people learn to do without quite realizing they are learning it. We spend twenty years (or more) learning how to speak properly and learning how to make good decisions and establish good relationships. But we tend to not know what we know. We can speak properly without knowing how we do it. We don't know how we comprehend. We just do.

All this poses a problem for AI. How can we imitate what humans are doing when humans don't know what they are doing when they do it? This conundrum led to a major failure in AI, expert systems, that relied upon rules that were supposed to characterize expert knowledge. But, the major characteristic of experts is that they get faster when they know more, while more rules made systems slower. The idea that rules were not at the center of intelligent systems meant that the flaw was relying upon specific consciously stated knowledge instead of trying to figure out what people meant when they said they just knew it when they saw it, or they had a gut feeling.

People give reasons for their behaviors but they are typically figuring that stuff out after the fact. We reason non-consciously and explain rationally later. Humans dream. There obviously is some important utility in dreaming.  Even if we don't understand precisely what the consequences of dreaming are, it is safe to assume that it is an important part of our unconscious reasoning process that drives our decision making. So, an intelligent machine would have to dream because it needed to, and would have to have intuitions that proved to be good insights, and it would have to have a set of driving goals that made it see the world in a way that a different entity with different goals would not. In other words it would need a personality, and not one that was artificially installed but one that came with the territory of what is was about as an intelligent entity.

What AI can and should build are intelligent special purpose entities. (We can call them Specialized Intelligences or SI's.) Smart computers will indeed be created. But they will arrive in the form of SI's, ones that make lousy companions but know every shipping accident that ever happened and why (the shipping industry's SI) or as an expert on sales (a business world SI.)   The sales SI, because sales is all it ever thought about, would be able to recite every interesting sales story that had ever happened and the lessons to be learned from it. For some salesman about to call on a customer for example, this SI would be quite fascinating. We can expect a foreign policy SI that helps future presidents learn about the past in a timely fashion and helps them make decisions because it knows every decision the government has ever made and has cleverly indexed them so as to be able to apply what it knows to current situations. 

So AI in the traditional sense, will not happen in my lifetime nor in my grandson's lifetime. Perhaps a new kind of machine intelligence will one day evolve and be smarter than us, but we are a really long way from that.

Near the end of his life Charles Darwin invited for lunch at Down House Dr Ludwig Büchner, President of the Congress of the International Federation of Freethinkers, and Edward Aveling, a self-proclaimed and active atheist.  The invitation was at their request.  Emma Darwin, devout as ever, was appalled by the thought of entertaining such guests and at table insulated herself from the atheists with an old family friend, the Rev. Brodie Innes, on her right and with her grandson and his friends on her left.  After lunch Darwin and his son Frank smoked cigarettes with the two visitors in Darwin's old study.  Darwin asked them with surprising directness: "Why do you call yourselves atheists?"  He said that he preferred the word agnostic.  While Darwin agreed that Christianity was not supported by evidence, he felt that atheist was too aggressive a term to describe his own position.

For many years what had been good enough for Darwin was good enough for me.  I too described myself as an agnostic.  I had been brought up in a Christian culture and some of the most rational humanists I knew were believers.  I loved the music and art that had been inspired by a belief in God and saw no hypocrisy in participating in the great carol services held in the Chapel of King's College Cambridge. I did not accept the views of some of my scientific colleagues that the march of science has disposed of religion.  The wish that I and many biologists had to understand biological evolution was not the same as the wish had by those with deep religious conviction to understand the meaning of life.

I had, however, led a sheltered life and had never met anybody who was aggressively religious.  I hated, of course, what I had read about the ugly fanaticism of all forms of religious fundamentalism or what I had seen of it on television.  However, such wickedness did not seem to be simply correlated with religious belief since many non-believers were just as totalitarian in their behaviour as the believers.   My unwillingness to be involved in religious debates was shaken at a grand dinner party.  The woman sitting next to me asked me what I did and I told her that I am a biologist.  "Oh well," she said, "then we have plenty to talk about, because I believe that every word of the Bible is literally true."  My heart sank.

As things turned out, we didn't have a great deal to talk about because she wasn't going to be persuaded by any argument that I could throw at her.  She did not seem to wonder about the inconsistencies between the gospels of the New Testament or those between the first and second chapters of Genesis.  Nor was she concerned about where Cain's wife came from?  The Victorians were delicate about such matters and were not going to entertain the thought that Cain married an unnamed sister or, horrors, that his own mother bore his children, his grand children and so on down the line of descendants until other women became available.  Nevertheless, the devout Victorians were obviously troubled by the question and they speculated on the existence of pre-Adamite people, angels probably, who would have furnished Cain with his wife.

My creationist dinner companion was not worried by such trivialities and dismissed my lack of politesse as the problem of a scientist being too literal.  However, being too literal was not my problem, it was hers and those of her fellow creationists.   She was hoist on her own petard.  In any event, it was quite simply stupid to try to take on science on its own terms by appealing to the intelligence implicit in natural design.  Science provides orderly methods for examining the natural world.  One of those methods is to develop theories that integrate as much as possible of what we know about the phenomena encompassed by the theory.  The theories provide frameworks for testing the characteristics of the world — and though some theorists may not wish to believe it, their theories are eminently disposable.  Facts are widely shared opinions and, every so often the consensus breaks — and minds change.  Nevertheless it is crying for the moon to hope that the enormous bodies of thought that have been built up about cosmology, geology and biological evolution are all due to fall apart.  No serious theologian would rest his or her beliefs on such a hope. If faith rests on the supposed implausibility of a current scientific explanation, it is vulnerable to the appearance of a plausible one.  To build on such sand is a crass mistake.

Not long after that dreadful dinner, Richard Dawkins wrote to me to ask whether I would publicly affirm my atheism.  I could see no reason why not.  One of the clear definitions of an atheist is a lack of a belief in a God.  That certainly described my position, even though I am disinclined to attack the beliefs of the sincere and thoughtful people with strong religious beliefs whom I continue to meet.  I completed the questionnaire that Richard had sent to me.  I had changed my mind. A dear friend, Peter Lipton, who died suddenly in November 2007, had been assiduous in maintaining Jewish customs in his own home and in his public defence of Israel.  After he died I was surprised to discover that he described himself as a religious atheist.  I should not have been surprised.

The 20th century has been obsessed with this idea of the objects and hopes of architectural and artistic permanence which nobody questionned more thouroughly than the late Cedric Price. The 21st century will increasingly question this fetishization of the object.

What are the architectural and artistic contributions which are going to endure they are not only the ones which have a built physical form. Its not only a question of objects but a questions of ideas and scores.

In a converation I had with her some months ago Doris Lessing questionned the future of museums. It's not that she's fundamentally opposed to these institutions, but she's worried that their prioritisation of material objects from the past may not be enough to convey functional meaning to tomorrow's generations. Her 1999 novel, Mara and Dann, is premised on the aftermath of an ice age thousands of years into the future that has eradicated the entirety of life in the northern hemisphere. Her protagonists, long since confined to the other side of the globe, embark upon a journey but they are at a loss with the cultural remnants; they have no grounding in its *artefacts and cities.

This is pure fiction, but she is nevertheless reticent that 'our entire culture is extremely fragile' In light of point, Lessing urges us to take pause and to reconsider the capacity of our language and cultural systems to proffer knowledge to those outside of our immediate public.

Public discourse on very long-term planning is riddled with inconsistencies. Mostly we discount the future very heavily — investment decisions are expected to pay off within a decade or two. But when we do look further ahead — in discussions of energy policy, global warming and so forth — we underestimate the possible pace of transformational change. In particular, we need to keep our minds open — or at least ajar — to the possibility that humans themselves could change drastically within a few centuries.

Our medieval forebears in Europe had a cosmic perspective that was a million-fold more constricted than ours. Their entire cosmology — from creation to apocalypse — spanned only a few thousand years. Today, the stupendous time spans of the evolutionary past are part of common culture — except among some creationists and fundamentalists. Moreover, we are mindful of immense future potential. It seems absurd to regard humans as the culmination of the evolutionary tree. Any creatures witnessing the Sun's demise 6 billion years hence won't be human — they could be as different from us as we are from slime mould.

But, despite these hugely stretched conceptual horizons, the timescale on which we can sensibly plan, or make confident forecasts has got shorter rather than longer. Medieval people, despite their constricted cosmology, did not expect drastic changes within a human life; they devotedly added bricks to cathedrals that would take a century to finish. For us, unlike for them, the next century will surely be drastically different from the present. There is a huge disjunction between the every-shortening timescales of historical and technical change, and the near-infinite time spans over which the cosmos itself evolves.

Human-induced changes are occurring with runaway speed. It's hard to predict a mere century from now, because what will happen depends on us — this is the first century where humans can collectively transform, or even ravage, the entire biosphere. Humanity will soon itself be malleable, to an extent that's qualitatively new in the history of our species. New drugs (and perhaps even implants into our brains) could change human character; the cyberworld has potential that is both exhilarating and frightening. We can't confidently guess lifestyles, attitudes, social structures, or population sizes a century hence. Indeed, it's not even clear for how long our descendants would remain distinctively 'human'. Darwin himself noted that "not one living species will transmit its unaltered likeness to a distant futurity". Our own species will surely change and diversify faster than any predecessor —— via human-induced modifications (whether intelligently-controlled or unintended), not by natural selection alone. Just how fast this could happen is disputed by experts, but the post-human era may be only centuries away.

These thoughts might seem irrelevant to practical discussions — and best left to speculative academics and cosmologists. I used to think this. But humans are now, individually and collectively, so greatly empowered by rapidly changing technology that we can, by design, or as unintended consequences — engender global changes that resonate for centuries. And, sometimes at least, policy-makers indeed think far ahead.

The global warming induced by fossil fuels burnt in the next fifty years could trigger gradual sea level rises that continue for a millennium or more. And in assessing sites for radioactive waste disposal, governments impose the requirements that they be secure for ten thousand years.

It's real political progress that these long-term challenges are higher on the international agenda, and that planners seriously worry about what might happen more than a century hence.

But in such planning, we need to be mindful that it may not be people like us who confront the consequences of our actions today. We are custodians of a 'posthuman' future — here on Earth and perhaps beyond — that can't just be left to writers of science fiction.

Experimental art and experimental politics have traditionally been convivial bedfellows, though usually, in my opinion, with very little benefit to each other. George Bernard Shaw and his circle fervently supported Stalin against the mounting tide of evidence; the Mitfords supported Hitler, and numerous gifted Italian poets and artists were persuaded by Fascism. Similarly, in the late sixties and early seventies the avant garde art scene in London was overwhelmed with admiration for Chairman Mao.

As a young artist I was part of that scene, and though never a hardcore Maoist, I was impressed by some of his ideas: that intellectuals shouldn't be separated off from workers, for example, and that art should somehow serve working class society. I was sick of 'Art for Art's sake' and the insularity of the English art-world. I liked too the idea that professors should spend a month each year farming, or that designers should find out how it feels to work in a steel foundry. It sounded so benign from a distance. I felt, like many people felt at the time, that my society was by comparison stagnant, class-bound, stuck in history, and I admired Mao and the Chinese for their courage in reinventing themselves so dramatically.

Of course, the Americans were saying how dreadful it all was, but I thought "Well they would, wouldn't they?" In fact their criticism increased its credibility, for I believed America had gone fundamentally wrong, and her enemies must therefore be my friends. I assumed the US sensed the winds of change issuing from China, and was digging her heels in, resisting the future with all her might.

And then, bit by bit, I started to find out what had actually happened, what Maoism meant. I resisted for a while, but I had to admit it: I'd been willingly propagandised, just like Shaw and Mitford and d'Annunzio and countless others. I'd allowed my prejudices to dominate my reason. Those professors working in the countryside were being bludgeoned and humiliated. Those designers were put in the steel-foundries as 'class enemies' — for the workers to vent their frustrations upon.  I started to realise what a monstrosity Maoism had been, and that it had failed in every sense.

Thus began for me a long process of re-evaluation. I had to accept that I was susceptible to propaganda, and that propaganda comes from all sides — not just the one I happen to dislike. I realised that I was not by any means a neutral observer, that I came with my own set of prejudices which could be easily tweaked.

I realised too that I had to learn to evaluate opinions separately from those who were giving them: the truth might sometimes come out of a mouth I disliked, but that didn't automatically mean it wasn't the truth.

Maoism, or my disappointment with it, also changed my feelings about how politics should be done. I went from revolutionary to evolutionary. I no longer wanted to see radical change dictated from the top — even if that top claimed to be the bottom, the 'voice of the people'. I lost faith in the idea that there were quick solutions, that everyone would simultaneously see the light and things would suddenly flip over into a wonderful new reality. I started to believe it was always going to be slow, messy, compromised, unglamorous, bureaucratic, endlessly negotiated — or else extremely dangerous, chaotic and capricious. In fact I've lost faith in the idea of ideological politics altogether: I want instead to see politics as the articulation and management of a changing society in a changing world, trying to do a half-decent job for as many people as possible, trying to set things up a little better for the future.

Perhaps this is why I've increasingly come to regard the determinedly non-ideological, ecumenical EU as the signal political experiment of our time…

What have I changed my mind about? Online privacy.

For a long time, I thought that people would rise to the challenge and start effectively protecting their own privacy online, using tools and services that the market would provide. Many companies offered such services, and almost none of them succeeded (at least not with their original business plans). People simply weren't interested: They were both paranoid and careless, and took little trouble to inform themselves. (Of course, if you've ever attempted to read an online privacy statement, you'll understand why.)

But now I've simply changed my mind and realized that the whole question needs reframing - which Facebook et al. are in the process of doing. Users have never learned the power to say no to marketers who want their data...but they are getting into the habit of controlling it themselves because Facebook is teaching them that this is a natural thing to do.

Yes, Facebook certainly managed to draw attention to the whole "privacy" question with its Beacon tracking tool, but for most Facebook users the big question is how many people they can get to see their feed. They are happy to share their information with friends, and they consider it the most natural thing in the world to distinguish among friends (see new Facebook add-on applications such as Top Friends and Cliquey) and to manage their privacy settings to determine who can see which parts of their profile. So why shouldn't they do the same thing vis a vis marketers?

For example, I fly a lot, and I use various applications to let certain friends know where I am and plan to be. I'd be delighted to share that information with certain airlines and hotels if I knew they would send me special offers. (In fact, United Airlines once asked me to send in my frequent flyer statements from up to three competing airlines in exchange for 2000 bonus miles each. I gladly did so, and would have done it for free. I *want* United to know what a good customer I am...and how much more of my business they could win if they offered me even better deals.)

In short, for many users the Web is becoming a mirror, with users in control, rather than a heavily surveilled stage. The question isn't how to protect users' privacy, but rather how to give them better tools to control their own data - not by selling privacy or by getting them to "sell" their data, , but by feeding their natural fascination with themselves and allowing them to manage their own presence. What once seemed like an onerous, weird task becomes akin to self-grooming online.

This begs a lot of questions, I know, including real, coercive invasions of privacy by government agencies, but I think the in-control users of the future will be better equipped to fight back. Give them a little time and a few bad experiences, and they'll start to make the distinction between an airline selling seats and a government that simply won't allow you to take it off your buddy list.

I have been a true disciple of kin-selection theory ever since I discovered the wonders of social evolution as a young graduate student. Kin selection theory emphasizes the importance of relatedness (i.e. kin) in the evolution of social behavior. The essence of social living lies in sharing tasks amongst group members; for example some individuals may end up monopolizing reproduction (dominants or queens), whilst others defend or forage for the group (helpers or altruists). The key to understanding how sociality evolves rests on finding a watertight explanation for altruism. Why should any individual sacrifice their reproductive rights in order to help another individual reproduce?

When groups consist of families, there is an intuitive basis for the evolution of altruism. Helping relatives, with whom I share many of my genes, is potentially a lucrative strategy for passing my genes on to future generations. This reasoning led W.D. Hamilton to his theory of inclusive fitness, or kin selection, in 1964: a social action evolves if the benefit (b) weighted by the relatedness (r) between group members exceeds the costs (c) of that action (i.e. br>c). Evolution is satisfyingly parsimonious, so it is only natural that an apparently complicated thing like sociality can be explained in such simple terms.

I am certain I speak for many students of sociality in being eternally grateful to Hamilton in providing such an elegant theory with such clear predictions to test. Off we go, armed with Hamilton’s Rule to settle our quest for understanding what makes an animal social. There are three things to measure: relatedness between group members (or actors and recipients), costs (to the actor in being altruistic) and benefits (to the recipient in receiving help). Happily, the molecular revolution has brought gene-level analytical tools to behavioral ecologists, allowing relatedness to be quantified accurately. Costs and benefits are more problematic to quantify, as they might vary over an individual’s life-time. Relatedness, therefore could be a fast-track route to securing the secrets of sociality in a kin-selected context.

The social Hymenoptera (ants, bees and wasps) are an excellent group for studying sociality because they live in large groups and have a peculiar genetic sex-determination system (haplodiploidy), engendering high levels of relatedness. If relatedness predisposes any animal to be social, it will be the Hymenoptera. As an altruist in a social insect colony there are several ways by which you could favor your most closely related group members. You could selectively feed sibling brood that share the same parents as you. Or, you could eat the eggs laid by your siblings in preference to those laid by your mother (the queen). On planning an elopement from the homestead to start a new colony, you might choose full-sisters as your companions rather than a random relative. The predictions are elegant, simple and depend on the kin structure of a specific colony.

With insect cadavers mounting up in university freezers all over the world, we raced to test these predictions. The results were disheartening: worker wasps headed by multiply mated mother queens were not maximizing their indirect fitness by laying heaps of parthenogenetic male eggs; worker ants were unable to optimally manipulate the brood sex ratios (and hence their inclusive fitness) in relation to how many times their mother had mated; social wasps were feeding larvae in regard to their need rather than relatedness; swarming wasps were indiscriminate in who they founded new colonies with.

On the back of robust experiments like these, I have changed my mind about relatedness being the primary dictator of social evolution. Insects are unable to discriminate relatedness on an individual level. Instead, relatedness may act at the colony/population level, or simply in distinguishing kin from non-kin. This make sense. An individual-level kin discrimination mechanism is vulnerable to invasion by an occasional nepotist, who would favor its closest relatives over others. As the gene for nepotism spreads, the variation on which the kin-discrimination is based (e.g. chemical or visual cues) will disappear and individuals will no longer be able to tell kin from non-kin, let alone full siblings from half siblings: sociality breaks down. We knew this long before many of the kin-discrimination experiments were done, but optimism perseveres until enough evidence pervades.

Does this mean kin selection theory is wrong? Absolutely not! The reason for this is that relatedness is only one (albeit important) component of kin selection theory. The key is likely to be the interaction of a high (and variable) benefit to cost ratio from helping, and a positive relatedness between actors and recipients: relatedness does not have to be high for altruism to evolve, it just needs to be greater than the population average. I still believe you cannot hope to understand sociality unless you put relatedness at the top of your list. But, we need to complement the huge amount of data generated by the molecular hamster wheel with some serious estimates of the costs and benefits of social actions.

When journalists asked me about 20 years ago what the use of my research is, I proudly told them that it has no use whatsoever. I saw an analog to the usefulness of astronomy or of a Beethoven symphony. We don't do these things, I said, for their use, we do them because they are part of what it means to be human. In the same way, I said, we do basic science, in my case experiments on the foundations of quantum physics. it is part of being human to be curious, to want to know more about the world. There are always some of us who are just curious and they follow their nose and investigate with no idea in mind what it might be useful for. Some of us are even more attracted to a question the more useless it appears. I did my work only because I was attracted by both the mathematical beauty of quantum physics and by the counterintuitive conceptual questions it raises. So I told them all the time up to the early 1990s.

Then a new surprising development started. The scientific community discovered that the same fundamental phenomena of quantum physics suddenly became relevant for more and more novel ways of transmitting and processing of information. We now have the completely new field of quantum information science where some of the basic concepts are quantum cryptography, quantum computation and even quantum teleportation. All this points us towards a new information technology where the same strange fundamental phenomena which attracted me initially into the field are essential. Quantum randomness makes it possible for us in quantum cryptography to send messages such that they are secure against unauthorized third parties. Quantum entanglement, called by Einstein "spooky action at a distance" makes quantum teleportation possible. And quantum computation builds on all counterintuitive features of the quantum world together. When journalists ask me today what the use of my research is I proudly tell them of my conviction that we well have a full quantum information technology in the future, though its specific features are still very much to be developed. So, never say that your research is "useless".

At the end of The Structure of Scientific Revolutions, Thomas Kuhn suggested that it is reasonable to trust the general consensus of experts instead of a revolutionary idea, even when the revolutionary idea is consistent with a finding that could not be explained by  the general consensus.  He reasoned that the general consensus was reached by drawing together countless bits of evidence, and even though it could not explain everything, it had passed a gauntlet to which the revolutionary idea had not yet been subjected. 

Kuhn's idea seemed sufficiently plausible to lead me to generally trust the consensus of experts in disciplines outside my area of expertise.  I still think that it is wise to trust the experts when their profession has a good understanding of the processes under consideration.   This situation applies to experts on car maintenance, for example, because cars were made by people who shared their knowledge about the function of car parts, and top notch car mechanics learn this information.  It also applies generally to the main principles of mechanical and electrical engineering, biology, physics, and chemistry, because these principles are tested directly or indirectly by the countless studies. 

I am becoming convinced, however, that the opposite view is often true when the expert opinion pertains to the unknown: the longer and more widespread the accepted wisdom has been accepted, the more hesitant we should be to trust it, especially if the experts  have been studying the question intensively during this period of acceptance and contradictory findings or logic have been presented.  The reason is simple.  If an explanation has been widely and broadly accepted and convincing evidence still cannot be mustered, then it is quite reasonable to expect that the experts are barking up the wrong, albeit cherished, trees.  That is, its acceptance has more to do with the limitations of intellectual ingenuity than with evidence. 

This argument provides a clear guideline for allocating trust to experts: distrust expert opinion in accordance with what is not known about the subject.  This guideline is, of course, difficult to apply because one has to first ascertain whether a discipline actually has valid answers for a given area of inquiry.  Consider something as simple as a sprained ankle.  Evolutionary considerations suggest that the inflammation and pain associated with sprained ankles are adaptive responses to promote healing, and that suppressing them would be detrimental to long-term functionality of the joint.   I have searched the literature to find out whether any evidence indicates that treatment of sprained ankles with ice, compression, anti-inflammatories, and analgesics promotes or hinders healing and long-term functionality of the joint. In particular, I have been looking for comparisons of treated individuals with untreated controls.  I have not found any and am coming to the conclusion that this widely advocated expert opinion is a detrimental holdover from ancient Greek medicine, which often confused the return of the body to a more healthy appearance with the return of the body to a state of health.  

More generally, I am coming to the disquieting realization that much of scientific opinion and even more of medical opinion falls into the murky area circumscribed by a lack of adequate knowledge about the processes at hand.  This means that I must invoke broadly the guideline to distrust expert opinion in proportion to the lack of knowledge in the area. Although this has made me more objectionable, it has also been of great value intellectually and practically, as when, for example, I sprain my ankle.

One of my most basic assumptions about the relationship between mental effort and brain function has begun to crumble. Here's why.

My earliest research interests as a psychologist were in the ways mental training can shape biological systems.  My doctoral dissertation was a psychophysiological study of meditation as an intervention in stress reactivity; I found (as have many others since) that the practice of meditation seems to speed the rate of physiological recovery from a stressor.

My guiding assumptions included the standard premise that the mind-body relationship operates according to orderly, understandable principles.  One such might be called the "dose-response" rule, that the more time put into a given method of training, the greater the result in the targeted biological system.  This is a basic correlate of neuroplasticity, the mechanism through which repeated experience shapes the brain.

For example, a string of research has now established that more experienced meditators recover more quickly from stress-induced physiological arousal than do novices. Nothing remarkable there.  The dose-response rule would predict this is so. Thus brain imaging studies show that the spatial areas of London taxi drivers become enhanced during the first six months they spend driving around that city's winding streets; likewise, the area for thumb movement in the motor cortex becomes more robust in violinists as they continue to practice over many months.

This relationship has been confirmed in many varieties of mental training. A seminal 2004 article in the Proceedings of the National Academy of Science found that, compared to novices, highly adept meditators generated far more high-amplitude gamma wave activity — which reflects finely focused attention — in areas of the prefrontal cortex while meditating.

The seasoned meditators in this study — all Tibetan lamas — had undergone cumulative levels of mental training akin to the amount of lifetime sports practice put in by Olympic athletes: 10,000 to 50,000 hours. Novices tended to increase gamma activity by around 10 to 15 percent in the key brain area, while most experts had increases on the order of 100 percent from baseline. What caught my eye in this data was not this difference between novices and experts (which might be explained in any number of ways, including a self-selection bias), but rather a discrepancy in the data among the group of Olympic-level meditators.

Although the experts' average boost in gamma was around 100 percent, two lamas were "outliers": their gamma levels leapt 700 to 800 percent. This goes far beyond an orderly dose-response relationship — these jumps in high-amplitude gamma activity are the highest ever reported in the scientific literature apart from pathological conditions like seizures. Yet the lamas were voluntarily inducing this extraordinarily heightened brain activity for just a few minutes at a time — and by meditating on "pure compassion," no less.

I have no explanation for this data, but plenty of questions. At the higher reaches of contemplative expertise, do principles apply (as the Dalai Lama has suggested in dialogues with neuroscientists) that we do not yet grasp? If so, what might these be? In truth, I have no idea. But these puzzling data points have pried open my mind a bit as I've had to question what had been a rock-solid assumption of my own.

What gives rise to the most salient, contested and misunderstood of sex differences… differences that see men persistently walk off with the top positions and prizes, whether influence or income, whether heads of state or CEOs… differences that infuriate feminists, preoccupy policy-makers, galvanize legislators and spawn 'diversity' committees and degrees in gender studies?

I used to think that these patterns of sex differences resulted mainly from average differences between men and women in innate talents, tastes and temperaments. After all, in talents men are on average more mathematical, more technically minded, women more verbal; in tastes, men are more interested in things, women in people; in temperaments, men are more competitive, risk-taking, single-minded, status-conscious, women far less so. And therefore, even where such differences are modest, the distribution of these 3 Ts among males will necessarily be different from that among females — and so will give rise to notable differences between the two groups. Add to this some bias and barriers — a sexist attitude here, a lack of child-care there. And the sex differences are explained. Or so I thought.

But I have now changed my mind. Talents, tastes and temperaments play fundamental roles. But they alone don't fully explain the differences. It is a fourth T that most decisively shapes the distinctive structure of male — female differences. That T is Tails — the tails of these statistical distributions. Females are much of a muchness, clustering round the mean. But, among males, the variance — the difference between the most and the least, the best and the worst — can be vast. So males are almost bound to be over-represented both at the bottom and at the top. I think of this as 'more dumbbells but more Nobels'.

Consider the mathematics sections in the USA's National Academy of Sciences: 95% male. Which contributes most to this predominance — higher means or larger variance? One calculation yields the following answer. If the sex difference between the means was obliterated but the variance was left intact, male membership would drop modestly to 91%. But if the means were left intact but the difference in the variance was obliterated, male membership would plummet to 64%. The overwhelming male predominance stems largely from greater variance.

Similarly, consider the most intellectually gifted of the USA population, an elite 1%. The difference between their bottom and top quartiles is so wide that it encompasses one-third of the entire ability range in the American population, from IQs above 137 to IQs beyond 200. And who's overwhelmingly in the top quartile? Males. Look, for instance, at the boy:girl ratios among adolescents for scores in mathematical-reasoning tests: scores of at least 500, 2:1; scores of at least 600, 4:1; scores of at least 700, 13.1.

Admittedly, those examples are writ large — exceptionally high aptitude and a talent that strongly favours males and with a notably long right-hand tail. Nevertheless, the same combined causes — the forces of natural selection and the facts of statistical distribution — ensure that this is the default template for male-female differences.

Let's look at those causes. The legacy of natural selection is twofold: mean differences in the 3 Ts and males generally being more variable; these two features hold for most sex differences in our species and, as Darwin noted, greater male variance is ubiquitous across the entire animal kingdom. As to the facts of statistical distribution, they are three-fold … and watch what happens at the end of the right tail: first, for overlapping bell-curves, even with only a small difference in the means, the ratios become more inflated as one goes further out along the tail; second, where there's greater variance, there's likely to be a dumbbells-and-Nobels effect; and third, when one group has both greater mean and greater variance, that group becomes even more over-represented at the far end of the right tail.

The upshot? When we're dealing with evolved sex differences, we should expect that the further out we go along the right curve, the more we will find men predominating. So there we are: whether or not there are more male dumbbells, there will certainly be — both figuratively and actually — more male Nobels.

Unfortunately, however, this is not the prevailing perspective in current debates, particularly where policy is concerned. On the contrary, discussions standardly zoom in on the means and blithely ignore the tails. So sex differences are judged to be small. And thus it seems that there's a gaping discrepancy: if women are as good on average as men, why are men overwhelmingly at the top? The answer must be systematic unfairness — bias and barriers. Therefore, so the argument runs, it is to bias and barriers that policy should be directed. And so the results of straightforward facts of statistical distribution get treated as political problems — as 'evidence' of bias and barriers that keep women back and sweep men to the top. (Though how this explains the men at the bottom is an unacknowledged mystery.)

But science has given us biological insights, statistical rules and empirical findings … surely sufficient reason to change one's mind about men at the top.

As a teenager growing up in the rural American Midwest, I played in a Christian rock band. We wrote worship songs, with texts on religious themes, and experienced the jubilation and transport of the music as a visitation by the Holy Spirit. Then one day, as my faith was beginning to waiver, I wrote a song with an explicitly nonreligious theme. To my surprise I discovered that when I performed it, I was overcome by the same feelings, and it dawned on me that maybe what we had experienced all along was our own spirits, that what had called to us was the power of music itself.

In truth, I wasn't thinking through much at the time. Later, as a graduate student of philosophy, I did start to think a lot about science and ethics, and I began to undergo a parallel shift of outlook. Having embraced a thoroughly naturalistic, materialistic worldview, I wondered: If everything is just matter, how could anything really matter? How could values be among the objective furniture of the universe? It is not as if anyone expected physicists to discover, alongside electrons, protons, and neutrons, a new fundamental moral particle--the moron?--which would show up in high magnitudes whenever people did nice things.

Then there was J. L. Mackie's famous argument from "queerness": objective values would have to be such that merely coming to appreciate them would motivate you to pursue them. But given everything we know about how ordinary natural facts behave (they seem to ask nothing of us), how could there possibly be states of affairs with this strange to-be-pursuedness built into them, and how could we come to appreciate them?

At the same time, I was taken in by the promises found in some early sociobiology that a new evolutionary science of human nature would supplant empty talk about objective values. As Michael Ruse once put it, "morality is just an aid to survival and reproduction," and so "any deeper meaning is illusory." Niceness may seem self-evidently right to us, but things could easily have been the other way around, had nastiness paid off more often for our ancestors.

I have since been convinced that I was looking at all of this in the wrong way. Not only are values a part of nature; we couldn't avoid them if we tried.

There is no doubt that had we evolved differently, we would value different things. However, that alone does not show that values are subjective. After all, hearing is accomplished by psychological mechanisms that evolved under natural selection. But it does not follow that the things we hear are any less real. Rather, the reality of the things around us helps to explain why we have the faculty to detect them. The evolved can put us in touch with the objective.

In fact, we are all intimately familiar with entities which are such that to recognize them is to be moved by them. We call them reasons, where a reason is just a consideration that weighs in favor of an action or belief. As separate lines of research by psychologist Daniel Wegner and psychiatrist George Ainslie (as synthesized and interpreted by Daniel Dennett) strongly suggest, our reasons aren't all "in the head," and we cannot help but heed their call.

At some point in our evolution, the behavioral repertoire of our ancestors became complex enough to involve the review and evaluation of numerous possible courses of action and the formation of intentions on the basis of their projected outcomes. In a word, we got options. However, as an ultrasocial species, for whom survival and reproduction depended on close coordination of behaviors over time, we needed to manage these options in a way that could be communicated to our neighbors. That supervisor and communicator of our mental economy is the self, the more-or-less stable "I" that persists through time and feels like it is the author of action. After all, if you want to be able to make reliable threats or credible promises, you need to keep track of who you are, were, and will be. According to this perspective, reasons are a human organism's way of taking responsibility for some of the happenings in its body and environment. As such, they are inherently public and shareable. Reasons are biological adaptations, every bit as real as our hands, eyes, and ears.

I do not expect (and we do not need) a "science of good and evil." However, scientific evidence can show how it is that things matter objectively. I cannot doubt the power of reasons without presupposing the power of reasons (for doubting). That cannot be said for the power of the Holy Spirit.

I always change my mind about everything, and I never change my mind about anything.

That flexibility is intrinsic to being human — more, to being conscious. We are (or should be) constantly learning new things, absorbing new information, and reacting to new ideas, so of course we are changing our minds. In the most trivial sense, learning and memory involve a constant remodeling of the fine details of the brain, and the only time the circuitry will stop changing is when we're dead. And in a more profound sense, our major ideas change over time: my 5-year-old self, my 15-year-old self, and my 25-year-old self were very different people with different priorities and different understandings of the world around them than my current 50-year-old self. This is simply in the nature of our existence.

In the context of pursuing science, however, there is a substantive context in which we do not change our minds: we have a commitment to following the evidence wherever it leads. We have a kind of overriding metaphysic that says that we should set out to find data that will change our minds about a subject — every good research program has as its goal the execution of observations and experiments that will challenge our assumptions — and about that all-important foundation of the scientific enterprise I have never changed my mind, nor can I, without abandoning science altogether.

In my own personal intellectual history, I began my academic career with a focus on neuroscience; I shifted to developmental neurobiology; I later got caught up in developmental biology as a whole; I am now most interested in the confluence of evolution and development. Have I ever changed my mind? I don't think that I have, in any significant way — I have instead applied a consistent attitude towards a series of problems.

If I embark on a voyage of exploration, and I set as my goals the willingness to follow any lead, to pursue any interesting observation, to overcome any difficulties, and I end up in some unpredicted, exotic locale that might be very different from my predictions prior to setting out, have I changed my destination in any way? I would say not; thesine qua non of science is not the conclusions we reach but the process we use to arrive at them, and that is the unchanging pole star by which we navigate.

When I started Seed, I had a fairly strong aversion to technology. Somehow, sometime, science and technology had become science-and-technology. Two worlds, dissimilar in many respects, likely linked in speech for the practical goal of raising funding and attention for basic research by showing the direct, immediate correlation with usable things. I felt then that the 'and' made science more perfunctory and less romantic. And that this was a bad thing on multiple counts.

In the last year, I've come to see the relationship between science and technology very differently. We have reached the point in physics and cosmology, neuroscience, and genetics at least where technology is quintessential to advancement. Technology is not merely making the practice of science faster, less mundane or, as with microscopes, helping us see the otherwise unseeable; it is a distinct yet complementary landscape from which we can advance our knowledge of the natural world.

A physicist at CERN said to me recently that they likely wouldn't have built a new $8 billion collider if there was a better way of moving the field forward. The Blue Brain Project is using supercomputers to construct a mind because the neuroscientists involved believe it is the best way of attaining an overall understanding of the brain. Robots, I now appreciate, are not simply novelty items or tools of automation, but can be a way of gaining unique insight into humans. From simulation to supercomputing, technology is now (or at least I now see) one of science's very best friends (I could say the same for the arts). And the design, magnitude, and complexity of these technological feats satisfy my (and our) need for romance in our pursuit of truth.

The sum total of all information produced in 2008 will likely exceed the amount of information generated by humans over the past 40,000 years. Science is getting literally bigger, but as these and other major experiments churn out pentabytes of data, how do we ensure that we are actually learning more? Visualization, and more generally a strong relationship between science and design, will be essential to deriving knowledge from all this information.

In the past few years, I have been thinking and writing about "attention", and specifically, "continuous partial attention". The impetus came from my years of working at Apple, and then, Microsoft, where I thought a lot about user interface as well as our relationship to the tools we create.

I believe that attention is the most powerful tool of the human spirit and that we can enhance or augment our attention with practices like meditation and exercise, diffuse it with technologies like email and Blackberries, or alter it with pharmaceuticals. 

But lately I have observed that the way in which many of us interact with our personal technologies makes it impossible to use this extraordinary tool of attention to our advantage.

In observing others — in their offices, their homes, at cafes — the vast majority of people hold their breath especially when they first begin responding to email. On cell phones, especially when talking and walking, people tend to hyper-ventilate or over-breathe. Either of these breathing patterns disturbs oxygen and CO2 balance.

Research conducted by two NIH scientists, Margaret Chesney and David Anderson, demonstrates that breath holding can contribute significantly to stress-related diseases. The body becomes acidic, the kidneys begin to re-absorb sodium, and as the oxygen and CO2 balance is undermined, our biochemistry is thrown off.

Around this same time, I became very interested in the vagus nerve and the role it played.  The vagus nerve is one of the major cranial nerves, and wanders from the head, to the neck, chest and abdomen.  It's primary job is to mediate the autonomic nervous system, which includes the sympathetic — "fight or flight," and parasympathetic — "rest and digest" nervous systems.   

The parasympathetic nervous system governs our sense of hunger and satiety, flow of saliva and digestive enzymes, the relaxation response, and many aspects of healthy organ function.  Focusing on diaphragmatic breathing enables us to down regulate the sympathetic nervous system, which then causes the parasympathetic nervous system to become dominant.  Shallow breathing, breath holding and hyper-ventilating triggers the sympathetic nervous system, in a "fight or flight" response.

The activated sympathetic nervous system causes the liver to dump glucose and cholesterol into our blood, our heart rate increases, we don't have a sense of satiety, and our bodies anticipate and resource for the physical activity that, historically, accompanied a physical fight or flight response.  Meanwhile, when the only physical activity is sitting and  responding to email, we're sort of "all dressed up with nowhere to go."    

Some breathing patterns favor our body's move toward parasympathetic functions and other breathing  patterns favor a sympathetic nervous system response.  Buteyko (breathing techniques developed by a Russian M.D.), Andy Weil's breathing exercises, diaphragmatic breathing, certain yoga breathing techniques, all have the potential to soothe us, and to help our bodies differentiate when fight or flight is really necessary and when we can rest and digest. 

I've changed my mind about how much attention to pay to my breathing patterns and how important it is to remember to breathe when I'm using a computer, PDA or cell phone. 

I've discovered that the more consistently I tune in to healthy breathing patterns, the clearer it is to me when I'm hungry or not, the more easily I fall asleep and rest peacefully at night, and the more my outlook is consistently positive. 

I've come to believe that, within the next 5-7 years, breathing exercises will be a significant part of any fitness regime.

Having grown up in Mexico, it took me a long time to understand what true power is and where it comes from. You see, I had great role models; perhaps that was part of the problem.  Throughout the developing world, as in Lansing and Iowa, there are many smart, tough, hardworking folk who still think power resides in today’s politics, unions, punditry, faith, painting, poetry, literature, agriculture, manufacturing, or architecture. Each sphere can immortalize or destroy individuals or regions. But, long term, to paraphrase Darwin, the only way for a country to survive and thrive is to adapt and adopt. 

Problem is there is a winner’s bias. To paraphrase a winemaker, tradition is an experiment that worked. A religion originally thrives because adherents find it improves their lives. Sometimes faith is a way to cope with the horror of the present and to improve health and survival. (Suppose there is any regional basis for the coincidences in Kosher and Halal restrictions?)  But most religions, and most countries, forget they became powerful by continuously experimenting, learning, tweaking, improving. They begin to ossify myths and traditions. As others grow and thrive, they begin to fear change. They celebrate the past, becoming more nativist and xenophobic. 

The rest of the world does not wait. It keeps gathering data. It keeps changing minds and methods. Successful religions and countries evolve new testaments and beliefs from the foundations of the old. The alternative is to merge, fragment, become irrelevant, go extinct. Museum basements are full of statues of once all powerful emperors and Gods that demanded, and got, blood sacrifices. 

Who is truly powerful over the long term? Those running most of the successful experiments.  And nowhere does this happen faster, more effectively, and more often today than in science-related endeavors. True power flows primarily from science and knowledge.

As we double the amount of data generated by our species over the course of the next five years, universities and science-driven businesses are the key drivers of new experiments. You can find many examples of fast growing countries that are rich and poor, North and South, communist, capitalist, and socialist. But all have a core of great science schools and tech entrepreneurs. Meanwhile much of Latin America lacks many Silicon Valley wannabes. Start ups are rare. Serial entrepreneurs sell cheap Chinese imports on sidewalks instead of dreaming up IPOs. Scientists often earn less than accountants. Real growth has been absent for decades. 

Few governments understand how quickly they must change, adopt, teach, and celebrate the new. (Never mind religions).  It is no coincidence that some of the fastest growing regions today were either isolated or largely irrelevant a few of decades ago. Singapore, Ireland, China, India and Korea, were considered basket cases. But often those with little to lose sometimes risk a new strategy.

Who eventually survives will be largely driven by understanding and applying digital and life code, by creating robots and nanomaterials, by working inconceivably large data sets and upgrading our brains. Meanwhile many U.S. leaders proudly proclaim no evolution and little knowledge of science. They reflect a core of scared voters experiencing massive disruption and declining wages; that core fears elite education, science, immigrants, open borders, and above all rapid change.  As income and knowledge gaps widen, many fall further and further behind; many grow to hate an open, knowledge driven economy. Change is rejected, blocked, vilified.

It took me a long time to shift focus from the politics, art, literature, and concerns of today towards the applied science of tomorrow. But had I not done that, I would have found it much harder to understand  which countries are likely to succeed and which could disappear.  And the disappearance and fragmentation of whole nations is an ever more common phenomenon.  Without the ability to adapt and adopt to science driven change, no matter what type of government, geography, ethnicity, or historic tradition you have, you will find that power devolves… even in the most powerful of empires.

I am a heretic. I have come to question the key assumption behind this survey: "When facts change your mind, that's science." This idea that science is an objective fact-driven pursuit is laudable, seductive and - alas - a mirage.

Science is a never-ending dialogue between theorists and experimenters. But people are central to that dialogue. And people ignore facts. They distort them or select the ones that suit their cause, depending on how they interpret their meaning. Or they don't ask the right questions to obtain the relevant facts.

Contrary to the myth of the ugly fact that can topple a beautiful theory - and against the grain of our lofty expectations - scientists sometimes play fast and loose with data, highlighting what that suits them and ignoring stuff that doesn't.

The harsh spotlight of the media often encourages them to strike a confident pose even if the facts don't. I am often struck by how facts are ignored, insufficient or even abused. I back well-designed animal research but am puzzled by how scientists chose to ignore the basic fact that vivisection is so inefficient at generating cures for human disease. Intelligent design is for cretins but, despite the endless proselytizing about the success of Darwin - assuming that evolution is a fact - I could still see it being superseded, rather as Einstein's ideas replaced Newton's law of gravity. I believe in man-made global warming but computer-projected facts that purportedly say what is in store for the Earth in the next century leave me cold.

I support embryo research but was irritated by one oft-cited fact in the recent British debate on the manufacture of animal-human hybrid embryos: "only a tiny fraction" of the hybrid made by the Dolly cloning method (nuclear transfer) contains animal DNA. Given that it features in mitochondria, which are central to a range of diseases; given a single spelling mistake in DNA can be catastrophic; and given no-one really understands what nuclear transfer does, this "fact" was propaganda.

Some of the most exotic and prestigious parts of modern science are unfettered by facts. I have recently written about whether our very ability to study the heavens may have shortened the inferred lifetime of the cosmos, whether there are two dimensions of time, even the prospect that time itself could cease to be in billions of years. The field of cosmology is in desperate need of more facts, as highlighted by the aphorisms made at its expense ("There is speculation, pure speculation and cosmology.... cosmologists are often in error, never in doubt')

Scientists have to make judgements about the merits of new facts. Ignoring them in the light of strong intuition is the mark of a great scientist. Take Einstein, for example: when Kaufmann claimed to have experimental facts that refuted special relativity, he stuck to his guns and was proved right. Equally, Einstein's intuition misled him in his last three decades, when he pursued a fruitless quest for a unified field theory that was not helped by his lack of interest in novel facts - the new theoretical ideas, particles and interactions that had emerged at this time.

When it comes to work in progress, in particular, many scientists treat science like a religion - the facts should be made to fit the creed. However, facts are necessary for science but not sufficient. Science is when, in the face of extreme scepticism, enough facts accrue to change lots of minds.

Our rising and now excessive faith in facts alone can be seen in a change in the translation of the motto of the world's oldest academy of science, the Royal Society. Nullius in Verba was once taken as 'on the word of no one' to highlight the extraordinary power that empirical evidence bestowed upon science. The message was that experimental evidence trumped personal authority.

Today the Society talks of the need to 'verify all statements by an appeal to facts determined by experiment'. But whose facts? Was it a well-designed experiment? And are we getting all the relevant facts? The Society should adopt the snappier version that captures its original spirit: 'Take nobody's word for it'.

I have never thought that female sexual psychology was simple.  But I've changed my mind about the magnitude of its complexity and consequently revamped the scope and orchestration of my entire research program.  I once focused my research on two primary sexual strategies — long-term and short-term.  Empirical work has revealed a deeper, richer repertoire: serial mating, friends with benefits, one-night stands, brief affairs, enduring affairs, polyamory, polyandry, sexual mate poaching, mate expulsion, mate switching, and various combinations of these throughout life.  Women implement their sexual strategies through an astonishing array of tactics.  Scientists have documented at least 34 distinct tactics for promoting short-term sexual encounters and nearly double that for attracting a long-term romantic partner.  

Researchers discovered 28 tactics women use to derogate sexual competitors, from pointing out that her rival's thighs are heavy to telling others that the rival has a sexually transmitted disease.  Women's sexual strategies include at least 19 tactics of mate retention, ranging from vigilance to violence, and 29 tactics of ridding themselves of unwanted mates, including having sex as a way to say good-bye.  Some women use sexual infidelity as a means of getting benefits from two or more men.  Others use it as a means of exiting one relationship in order to enter another.  When a woman wants a man who is already in a relationship, she can use at least 19 tactics of mate poaching to lure him away, from befriending both members of the couple in order to disarm her unsuspecting rival to insidiously sowing seeds of doubt about her rival's fidelity or level of desirability. 

Ovulation and orgasm are yielding scientific insights into female sexuality unimagined five years ago.  The hidden rhythms of the ovulation cycle, for example, have profound effects on women's sexual desire. Women married to men lower in mate value experience an upsurge in sexual fantasies about other men, but mainly during the fertile phase of their cycle.  They are sexually attracted to men with masculine faces, but especially so in the five days leading up to ovulation.  Women's sense of smell spikes around ovulation.  Sexual scents, long thought unimportant in human sexuality, in fact convey information to women about a man's genetic quality.  The female orgasm, once thought by many scientists to be functionless, may turn out to have several distinct adaptive benefits.  And those don't even include the potential gains from faking orgasm.  Some women mislead about their sexual satisfaction in order to get a man to leave; others to deceive him about his paternity in "his" child.  

Female sexual psychology touches every facet of human affairs, from cooperative alliances through strategies of hierarchy negotiation.  Some women use sex to get along.  Some use sex to get ahead.  Sexual motives pervade murder.  Failure in sexual unions sometimes triggers suicidal ideation.  I thought the complexity of women's sexual psychology was finally starting to be captured when recent research revealed 237 reasons why women have sex, ranging from "to get rid of a headache" to "to get closer to God," from "to become emotionally connected with my partner" to "to break up a rival's relationship."  Within a month of that publication, however, researchers discovered another 44 reasons why women have sex ranging from "because life is short and we could die at any moment" to "to get my boyfriend to shut up," bringing the sexual motivation total to 281 and still counting (obviously, trying to pin down exact numbers is a bit of a joke, but scientists work through quantification).

Yet with all these scientific discoveries, I feel that we are still at the beginning of the exploration and humbled by how little we still know.  As a researcher focusing on female sexuality, I'm inherently limited by virtue of possessing a male brain.  Consequently, I've teamed up with brilliant female research scientists, recruited a team of talented female graduate students, and marshaled much of my research to explore the complexities of female sexual psychology.  They have led me to see things previously invisible to my male-blinkered brain.  Female sexual psychology is more complex than I previously thought by several orders of magnitude.  And still I may be underestimating.

I work in a borderland between social science and medicine, and I therefore often find myself trying to reconcile conflicting facts and perspectives about human biology and behavior.  There are fellow travelers at this border, of course, heading in both directions, or just dawdling, but the border is both sparsely populated and chaotic.  The border is also, strangely, well patrolled, and it is often quite hard to get authorities on both sides to coordinate activities.  Once in a while, however, I find that my passport (never quite in order, according to officials) has acquired a new visa.  For me, this past year, I acquired the conviction that human evolution may proceed much faster than I had thought, and that humans themselves may be responsible. 

In short, I have changed my mind about how people come literally to embody the social world around them.  I once thought that we internalized cultural factors by forming memories, acquiring language, or bearing emotional and physical marks (of poverty, of conquest).  I thought that this was the limit of the ways in which our bodies were shaped by our social environment.  In particular, I thought that our genes were historically immutable, and that it was not possible to imagine a conversation between culture and genetics.  I thought that we as a species evolved over time frames far too long to be influenced by human actions. 

I now think this is wrong, and that the alternative — that we are evolving in real time, under the pressure of discernable social and historical forces — is true.  Rather than a monologue of genetics, or a soliloquy of culture, there is a dialectic between genetics and culture.

Evidence has been mounting for a decade. The best example so far is the evolution of lactose tolerance in adults.  The ability of adults to digest lactose (a sugar in milk) confers evolutionary advantages only when a stable supply of milk is available, such as after milk-producing animals (sheep, cattle, goats) have been domesticated.  The advantages are several, ranging from a source of valuable calories to a source of necessary hydration during times of water shortage or spoilage.  Amazingly, just over the last 3-9 thousand years, there have been several adaptive mutations in widely separated populations in Africa and Europe, all conferring the ability to digest lactose (as shown by Sarah Tishkoff and others).  These mutations are principally seen in populations who are herders, and not in nearby populations who have retained a hunter/gatherer lifestyle. This trait is sufficiently advantageous that those with the trait have notably many more descendants than those without.

A similar story can be told about mutations that have arisen in the relatively recent historical past that confer advantages in terms of surviving epidemic diseases such as typhoid.  Since these diseases were made more likely when the density of human settlements increased and far-flung trade became possible, here we have another example of how culture may affect our genes.

But this past year, a paper by John Hawks and colleagues in PNASfunctioned like the staccato plunk of a customs agent stamping my documents and waving me on.  The paper showed that the human genome may be changing at an accelerating rate over the past 80,000 years, and that this change may be in response not only to population growth and adaptation to new environments, but also to cultural developments that have made it possible for humans to sustain such population growth or survive in such environments.

Our biology and our culture have always been in conversation of course — just not (I had thought) on the genetic level.  For example, rising socio-economic status with industrial development results in people becoming taller (a biological effect of a cultural development) and taller people require architecture to change (a cultural effect of a biological development).  Anyone marveling at the small size of beds in colonial-era houses knows this firsthand.  Similarly, an epidemic may induce large-scale social changes, modifying kinship systems or political power.  But genetic change over short time periods?  Yes.

Why does this matter?  Because it is hard to know where this would stop.  There may be genetic variants that favor survival in cities, that favor saving for retirement, that favor consumption of alcohol, or that favor a preference for complicated social networks.  There may be genetic variants (based on altruistic genes that are a part of our hominid heritage) that favor living in a democratic society, others that favor living among computers, still others that favor certain kinds of visual perception (maybe we are all more myopic as a result of Medieval lens grinders).  Modern cultural forms may favor some traits over others.  Maybe even the more complex world we live in nowadays really is making us smarter. 

This has been very difficult for me to accept because, unfortunately, this also means that it may be the case that particular ways of living create advantages for some, but not all, members of our species.  Certain groups may acquire (admittedly, over centuries) certain advantages, and there might be positive or negative feedback loops between genetics and culture.  Maybe some of us really are better able to cope with modernity than others.  The idea that what we choose to do with our world modifies what kind of offspring we have is as amazing as it is troubling.

We do not so much change our minds about facts, although we necessarily correct and rearrange them in changing contexts. But we do change our minds about the significance of those facts.

I can remember, as a young woman, first grasping the danger of environmental destruction at a conference in 1968.  The context was the intricate interconnection within all living systems, a concept that applied to ecosystems like forests and tide pools and equally well to human communities and to the planet as a whole, the sense of an extraordinary interweaving of life, beautiful and fragile, and threatened by human hubris. It was at that conference also that I first heard of the greenhouse effect, the mechanism that underlies global warming. A few years later, however, I heard of the Gaia Hypothesis (proposed by James Lovelock in 1970), which proposed that the same systemic interconnectivity gives the planet its resilience and a capacity for self correction that might survive human tampering. Some environmentalists welcomed the Gaia hypothesis, while others warned that it might lead to complacency in the face of real and present danger. With each passing year, our knowledge of how things are connected is enriched but the significance of these observations is still debated.

J.B.S. Haldane was asked once what the natural world suggested about the mind of its Creator, and he replied "an inordinate fondness for beetles." This observation also plays differently for different listeners—a delight in diversity, perhaps, as if the Creator might have spent the first sabbath afternoon resting from his work by playfully exploring the possible ramifications of a single idea (beetles make up roughly one fifth of all known species on the planet, some 350,000 of them)—or a humbling (or humiliating?) lack of preoccupation with our own unique kind, which might prove to be a temporary afterthought, survived only by cockroaches.

These two ways of looking at what we observe seem to recur, like the glass half full and the glass half empty.  The more we know of the detail of living systems, the more we seem torn between anxiety and denial on the one hand and wonder and delight on the other as we try to understand the significance of our knowledge. Science has radically altered our awareness of the scale and age of the universe, but this changing awareness seems to stimulate humility in some—our planet a tiny speck dominated by flea-like bipeds—and a sort of megalomania in others who see all of this as directed toward us, our species, as its predestined masters. Similarly, the exploration of human diversity in the twentieth century expanded for some the sense of plasticity and variability and for others reinforced the sense of human unity. Even within these divergent emphases, for some the recognition of human unity includes a capacity for mutual recognition and adaptation while for others it suggests innate tendencies toward violence and xenophobia. As we have slowly explored the mechanisms of memory and learning, we have seen examples of (fragile) human communities demoralized by exposure to other cultures and (resilient) examples of extraordinary adaptability. At one moment humans are depicted as potential stewards of the biosphere, at another as a cancer or a dangerous infestation. The growing awareness of a shared and interconnected destiny has a shadow side, the version of globalization that looks primarily for profit.

We are having much the same sort of debate at present between those who see religion primarily as a source of conflict between groups and others who see the world's religions as potentially convergent systems that have knit peoples together and laid the groundwork for contemporary ideas of human rights and civil society. Some believers feel called to treasure and respect the creation, including the many human cultures that have grown within it, while others regard differences of belief as sinful and the world we know as transitory or illusory. Each of the great religions, with different language and different emphases, offers the basis for environmental responsibility and for peaceful coexistence and compassion, but believers differ in what they choose to emphasize, all too many choosing the apocalyptic over the ethical texts. Nevertheless, major shifts have been occurring in the interpretation of information about climate change, most recently within the evangelical Christian community.   

My guess is that many people have tilted first one way and then the other over the past fifty years, as we have become increasingly aware of diverse understandings—surprised by accounts of human creativity and adaptation on the one hand, and distressed at the resurgence of ancient quarrels and loss of tolerance and mutual respect. Some people are growing away from irresponsible consumerism while others are having their first taste of affluence. Responses are probably partly based on temperament—generalized optimism vs. pessimism—so the tension will not be resolved by scientific findings. But these responses are also based on the decisions we make, on making up our minds about which interpretations we choose to believe. The world's historic religions deal in different ways with loss and the need for sacrifice, but the materials are there for working together, just as they are there for stoking conflict and competition.  We are most likely to survive this century if we decide to approach the choices and potential losses ahead with an awareness of the risks we face but at the same time with an awareness of the natural wonders around us and a determination to deal with each other with respect and faith in the possibility of cooperation and responsibility.
 

All right, we knew it. But now we have the whole picture of the molecular process through which past and future link; how the germinal soul, rooted in brain matter and memory, allows for new perceptions, for the future, to emerge. It is both simple and terrifying at the same time.

When the mind is challenged from the outside universe, it searches in its accumulated archives in order to make sense of this new stimulus. This screening of our memory –of our past- produces an immediate answer: the new stimulus either leaves everyone indifferent, or else it blooms into an emotion of love, of pleasure or of sheer curiosity. These are the three touchstones of creativity. So basically, science has discovered that at the very beginning at least, only the past matters. And that holds true also of our future creativity.

Then a process more akin to alchemy than science sparks off and develops into social intelligence. The imitation process, based on mirror neurons, interacts with the corpus of accumulated knowledge -of one´s own species, and of others- which, combined with a good stock of well preserved individual memory, explode into new thinking.

Until very recently, we were missing a fundamental step in the process of knowledge- namely, how to transform short term memory into long term knowledge. At last we are taking into account the detailed contents of durability, specific proteins without which there is no learning and affection in childhood, no schooling at a later stage, no socialization in adult life. The roots are in the past; but there is no knowledge if we hide in a cave alone, with no windows to peer from and no shadows dancing outside.

The past has to be worked upon from the outside in order to transform into the future, and this has brought about the second main discovery in the molecular process of creativity. The so called “technology transfer” from old to new generations is a two-way process: matter, mind, soul, past, memory, future, and also startling new ways of looking at old things, are all marvellously intertwined in the evolutionary process.

I change my mind all the time — keeping an open mind in science is a good thing. Most often these are rather unremarkable occasions; most often it is acceptance of something I had been unconvinced or unsure about. But then there is this one time …

October 4th, 1995 was a warm day. Florence was overrun by tourists – and a few scientists from a conference I was attending. The next day one of my older and esteemed colleagues from Geneva was going to announce a curious find – a star that seemed to have a very small companion – as small as a planet like Saturn or Jupiter. Such claims had come and gone in the decades past, but this time the data seemed very good. He was keeping the details to himself until the next day, but he told me when I asked him about the orbital period of the new planet. I was incredulous – the period was so short, it was measured in days, not years – I told my wife back in the hotel that night – just 400 days!

I was not a planetary scientist – stars were my specialty, but I knew my planetary basics – a planet like Jupiter could not possibly exist so close to its star and have a period of 400 days. Some of this I had learned as far back as last year of high school. I did not question it, instead I was questioning my colleague’s claim. He was the first to speak the next day and he began by showing the orbital period for the new planet – it was 4.2 days! The night before, I must have heard “4.2 days”, but being so incredibly foreign to my preconception, my brain had “translated” that number to a more “reasonable” 420 days, or – roughly 400. Deeply held preconceptions can be very powerful.

My Florentine experience took some time to sink in. But when it did, it was sobering and inspiring. It made me curious and motivated to find the answers to those questions that just days before I had taken for granted. And I ended up helping develop the new field of extrasolar planets research.

Like many people, I once trusted in the wisdom of Nature. I imagined that there were real boundaries between the natural and the artificial, between one species and another, and thought that, with the advent of genetic engineering, we would be tinkering with life at our peril. I now believe that this romantic view of Nature is a stultifying and dangerous mythology.

Every 100 million years or so, an asteroid or comet the size of a mountain smashes into the earth, killing nearly everything that lives. If ever we needed proof of Nature's indifference to the welfare of complex organisms such as ourselves, there it is. The history of life on this planet has been one of merciless destruction and blind, lurching renewal.

The fossil record suggests that individual species survive, on average, between one and ten million years. The concept of a "species" is misleading, however, and it tempts us to think that we, as homo sapiens, have arrived at some well-defined position in the natural order. The term "species" merely designates a population of organisms that can interbreed and produce fertile offspring; it cannot be aptly applied to the boundaries between species (to what are often called "intermediate" or "transitional" forms). There was, for instance, no first member of the human species, and there are no canonical members now. Life is a continuous flux. Our nonhuman ancestors bred, generation after generation, and incrementally begat what we now deem to be the species homo sapiens — ourselves.  There is nothing about our ancestral line or about our current biology that dictates how we will evolve in the future. Nothing in the natural order demands that our descendants resemble us in any particular way. Very likely, they will not resemble us. We will almost certainly transform ourselves, likely beyond recognition, in the generations to come.

Will this be a good thing? The question presupposes that we have a viable alternative. But what is the alternative to our taking charge of our biological destiny? Might we be better off just leaving things to the wisdom of Nature? I once believed this. But we know that Nature has no concern for individuals or for species. Those that survive do so despite Her indifference. While the process of natural selection has sculpted our genome to its present state, it has not acted to maximize human happiness; nor has it necessarily conferred any advantage upon us beyond the capacity raise the next generation to child-bearing age.  In fact, there may be nothing about human life after the age of forty (the average lifespan until the 20th century) that has been selected by evolution at all. And with a few exceptions (e.g. the gene for lactose tolerance), we probably haven't adapted to our environment much since the Pleistocene.

But our environment and our needs — to say nothing of our desires — have changed radically in the meantime. We are in many respects ill-suited to the task of building a global civilization. This is not a surprise. From the point of view of evolution, much of human culture, along with its cognitive and emotional underpinnings, must be epiphenomenal. Nature cannot "see" most of what we are doing, or hope to do, and has done nothing to prepare us for many of the challenges we now face.

These concerns cannot be waved aside with adages like, "if it ain't broke, don't fix it." There are innumerable perspectives from which our current state of functioning can be aptly described as "broke." Speaking personally, it seems to me that everything I do picks out some point on a spectrum of disability: I was always decent at math, for instance, but this is simply to say that I am like a great mathematician who has been gored in the head by a bull; my musical ability resembles that of a Mozart or a Bach, it is true, though after a near fatal incident on skis; if Tiger Woods awoke from surgery to find that he now possessed (or was possessed by) my golf-swing, rest assured that a crushing lawsuit for medical malpractice would be in the offing.

Considering humanity as a whole, there is nothing about natural selection that suggests our optimal design. We are probably not even optimized for the Paleolithic, much less for life in the 21st century. And yet, we are now acquiring the tools that will enable us to attempt our own optimization. Many people think this project is fraught with risk. But is it riskier than doing nothing? There may be current threats to civilization that we cannot even perceive, much less resolve, at our current level of intelligence. Could any rational strategy be more dangerous than following the whims of Nature? This is not to say that our growing capacity to meddle with the human genome couldn't present some moments of Faustian over-reach. But our fears on this front must be tempered by a sober understanding of how we got here. Mother Nature is not now, nor has she ever been, looking out for us.

Aside from whether Apple matters (whoops!), the biggest thing I've changed my mind about is climate change. There was no one thing that convinced me to flip from wait-and-see to the-time-for-debate-is-over. Instead, there were three things, which combined for me in early 2006. There was, of course, the scientific evidence, which kept getting more persuasive. There was also economics, and the recognition that moving to alternative, sustainable energy was going to be cheaper over the long run as oil got more expensive. And finally there was geopolitics, with ample evidence of how top-down oil riches destabilized a region and then the world. No one reason was enough to win me over to total energy regime change, but together they seemed win-win-win.

Now I see the entire energy and environmental picture through a carbon lens. It's very clarifying. Put CO2 above everything else, and suddenly you can make reasonable economic calculations about risks and benefits, without getting caught up in the knotty politics of full-spectrum environmentalism. I was a climate skeptic and now I'm a carbon zealot. I seem to annoy traditional environmentalists just as much, but I like to think that I've moved from behind to in front.

I've changed my mind about the manner in which our future on this planet might evolve.

I used to think that the power of science to dissect, inform, illuminate and clarify, its venerable record in improving the human condition, and its role in enabling the technological progress of the modern world were all so glaringly obvious that no one could reasonably question its hallowed position in human culture as the pre-eminent device for separating truth from falsehood.

I used to think that the edifice of knowledge constructed from thousands of years of scientific thought by various cultures all over the globe, and in particular the insights earned over the last 400 years from modern scientific methods, were so universally revered that we could feel comfortably assured of having permanently left our philistine days behind us.

And while I've always appreciated the need for care and perseverance in guiding public evaluation of the complexities of scientific discourse and its findings, I never expected that we would, at this stage in our development, have to justify and defend the scientific process itself.

Yet, that appears to be the case today. And now, I'm no longer sure that scientific inquiry and the cultural value it places on verifiable truth can survive without constant protection, and its ebb and flow over the course of human history affirms this. We have been beset in the past by dark ages, when scientific truths and the ideas that logically spring from them were systematically destroyed or made otherwise unavailable, when the practitioners of science were discredited, imprisoned, and even murdered. Periods of human enlightenment have been the exception throughout time, not the rule, and our language has acknowledged this: 'Two steps forward, one step back' neatly outlines the nonmonotonic stagger inherent in any reading of human history.

And, if we're not mindful, we could stagger again. When the truth becomes problematic, when intellectual honesty clashes with political expediency, when voices of reason are silenced to mere whisper, when fear alloys with ignorance to promote might over intelligence, integrity, and wisdom, the very practice of science can find itself imperiled. At that point, can darkness be far behind?

To avoid so dangerous a tipping point requires us, first and foremost, to recognize the distasteful possibility that it could happen again, at any time. I now suspect the danger will be forever present, the need for vigilance forever great.

I was an earnest student in Catechism class. The climax of our early training, as thirteen year-olds, was an intense retreat in preparation for the sacrament of Confirmation. Even now I vividly remember the rapture of belief, the glow everyday events acquired when I felt that they reflected a grand scheme of the universe, in which I had a personal place. Soon afterward, though, came disillusionment. As I learned more about science, some of the concepts and explanations in the ancient sacred texts came to seem clearly wrong; and as I learned more about history and how it is recorded, some of the stories in those texts came to seem very doubtful.

What I found most disillusioning, however, was not that the sacred texts contained errors, but that they suffered by comparison. Compared to what I was learning in science, they offered few truly surprising and powerful insights. Where was there a vision to rival the concepts of infinite space, of vast expanses of time, of distant stars that rivaled and surpassed our Sun? Or of hidden forces and new, invisible forms of "light"? Or of tremendous energies that humans could, by understanding natural processes, learn to liberate and control? I came to think that if God exists, He (or She, or They, or It ) did a much more impressive job revealing Himself in the world than in the old books; and that the power of faith and prayer is elusive and unreliable, compared to the everyday miracles of medicine and technology.

For many years, like some of my colleagues and some recent bestselling authors, I thought that active, aggressive debunking might be in order. I've changed my mind. One factor was my study of intellectual history. Many of my greatest heros in physics, including Galileo, Newton, Faraday, Maxwell, and Planck, were deeply religious people. They truly believed that what they were doing, in their scientific studies, was discovering the mind of God. Many of Bach's and Mozart's most awesome productions are religiously inspired. Saint Augustine's writings display one of the most impressive intellects ever. And so on. Can you imagine hectoring this group? And what would be the point? Did their religious beliefs make them stupid, or stifle their creativity?

Also, debunking hasn't worked very well. David Hume already set out the main arguments for religious skepticism in the early eighteenth century. Bertrand Russell and many others have augmented them since. Textual criticism reduces fundamentalism to absurdity. Modern molecular biology, rooted in physics and chemistry, demonstrates that life is a natural process; Darwinian evolution illuminates its natural origin. These insights have been highly publicized for many decades, yet religious doctrines that contradict some or all of them have not merely survived, but prospered.

Why? Part of the answer is social. People tend to stay with the religion of their birth, for the same sorts of reasons that they stay loyal to their clan, or their country.

But beyond that, religion addresses some deep concerns that science does not yet, for most people, touch. The human yearning for meaningful understanding, our fear of death — these deep motivations are not going to vanish. 

Understanding, of course, is what science is all about. Many people imagine, however, that scientific understanding is dry and mundane, with no scope for wonder and amazement. That is simply ignorant. Looking for wonder and amazement? Try some quantum theory!

Beyond understanding inter-connected facts, people want to discover their significance or meaning. Neuroscientists are beginning to map human motivations and drives at the molecular level. As this work advances, we will attain a deeper understanding of the meaning of meaning. Freud's theories had enormous impact, not because they are correct, but because they "explained" why people feel and act as they do. Correct and powerful theories that address these issues are sure to have much greater impact.

Meanwhile, medical science is taking a deep look at aging. Within the next century, it may be possible for people to prolong youth and good health for many years — perhaps indefinitely. This would, of course, profoundly change our relationship with death. So to me the important challenge is not to debunk religion, but to address its issues in better ways.

I have changed my mind about the general validity of the mechanical worldview that underlies the modern scientific understanding of natural processes. Trained in biology and mathematics, I have used the scientific approach to the explanation of natural phenomena during most of my career. The basic assumption is that whatever properties and behaviours have emerged naturally during cosmic evolution can all be understood in terms of the motions and interactions of inanimate entities such as elementary particles, atoms, molecules, membranes and organelles, cells, organs, organisms, and so on.

Modelling natural processes on the basis of these assumptions has provided explanations for myriad natural phenomena ranging from planetary motion and electromagnetic phenomena to the properties and behaviour of nerve cell and the dynamic patterns that emerge in ant colonies or flocks of birds. There appeared to be no limit to the power of this explanatory procedure, which enchanted me and kept me busy throughout most of my scientific career in biology.

However, I have now come to the conclusion that this method of explaining natural phenomena has serious limitations, and that these come from the basic assumptions on which it is based. The crunch came for me with the "explanation" of qualitative experience in humans and other organisms. By this I mean the experience of pain or pleasure or wellbeing, or any other of the qualities that are very familiar to us.

These are described as "subjective", that is, experienced by a living organism, because they cannot be isolated from the subject experiencing them and measured quantitatively. What is often suggested as an explanation of this is evolutionary complexity: when an organism has a nervous system of sufficient complexity, subjective experience and feelings can arise. This implies that something totally new and qualitatively different can emerge from the interaction of "dead", unfeeling components such as cell membranes, molecules and electrical currents.

But this implies getting something from nothing, which violates what I have learned about emergent properties: there is always a precursor property for any phenomenon, and you cannot just introduce a new dimension into the phase space of your model to explain the result. Qualities are different from quantities and cannot be reduced to them.

So what is the precursor of the subjective experience that evolves in organisms? There must be some property of neurones or membranes or charged ions producing the electric associated with the experience of feeling that emerges in the organism.

One possibility is to acknowledge that the world isn't what modern science assumes it to be, mechanical and "dead", but that everything has some basic properties relating to experience or feeling. Philosophers and scientists have been down this route before, and have called this pan-sentience or pan-psychism: the world is impregnated with some form of feeling in every one of its constituents. This makes it possible for the evolution of complex organised beings such as organisms to develop feelings and for qualities to be as real as quantities.

Pan-sentience shifts science into radically new territory. Science can now be about qualities as well as quantities, helping us to recover quality of life, to heal our relationship to the natural world, and to undo the damage we are causing to the earth's capacity to continue its evolution with us. It could help us to recover our place as participants in a world that is not ours to control, but is ours to contribute to creatively, along with all the other diverse members of our living, feeling, planetary society.

I've long considered myself as working at the boundary between physical science and computer science; I now believe that that boundary is a historical accident and does not really exist.

There's a sense in which technological progress has turned it into a tautological statement. It's now possible to store data in atomic nuclei and use electron bonds as logical gates. In such a computer the number of information-bearing degrees of freedom is on the same order as the number of physical ones; it's no longer feasible to account for them independently. This means that computer programs can, and I'd argue must, look more like physical models, including spatial and temporal variables in the density and velocity of information propagation and interaction. That shouldn't be surprising; the canon of computer science emerged a few decades ago to describe the available computing technology, while the canon of physics emerged a few centuries ago to describe the accessible aspects of nature. Computing technology has changed more than nature has; progress in the former is reaching the limits of the latter.

Conversely, it makes less and less sense to define physical theories by the information technology of the last millenium (a pencil and piece of paper); a computational model is every bit as fundamental as one written with calculus. This is seen in frontiers of research in nonlinear dynamics, and quantum field theories, and black hole thermodynamics, that look more and more like massively parallel programming models. However, the organization of research has not yet caught up with this content; many of the pioneers doing the work are in neither Physics nor Computer Science departments, but are scattered around (and off) campus. Rather than trying to distinguish between programming nature and the nature of programming, I think that it makes more sense to recognize not just a technology or theory of information, but a single science.

If asked years ago whether I believed in God, my answer would have gone something like this: "I believe there's something…" This response leaves enough wiggle room for a few quasi-religious notions to slip comfortably through. I no longer believe that my soul is immortal, that the universe sends me messages every now and then, or that my life story will unfold according to some inscrutable plan. But it is more like knowing how and why a perceptual illusion is deceiving my evolved senses than it is becoming immune to the illusion altogether. 
Here's a snapshot of how these particular illusions work:

Psychological Immortality
There's a scene in Gide's The Counterfeiters where a suicidal man puts a pistol to his temple but hesitates for fear of the noise from the blast. Similarly, a group of college students who rejected the idea that consciousness survives death nonetheless told me that someone who'd died in a car accident would know he was dead. "There's no afterlife," one participant said. "He sees that now." 
In wondering what it's like to be dead, our psychology responds by running mental simulations using previous states of consciousness. The trouble is that death is not like anything we've ever experienced — orcan experience. (What's it like to be conscious yet unconscious at the same time?) I doubt you'd find anyone who believes less in the afterlife, yet I have a very real fear of ghosts and I feel guilty for not visiting my mother's grave more often. 

Symbolic Meaning of Natural Events
Psychologist Becky Parker and I told a seven-year-old that an invisible princess was in the room with her. The task was to find a hidden ball by placing her hand on top of the box she thought it was inside. If you change your mind, we said, just move your hand to the other box. Now, Princess Alice likes you and she's going to help you find the ball. "I don't know how she's going to tell you," said Becky, "but somehow she'll tell you if you pick the wrong box."

The child picked a box, held her hand there, and after 15 seconds the box opened to reveal the ball (there were two identical balls). On the second trial, as soon as the girl chose a box, a picture crashed to the ground, and the child moved her hand to the other box. In doing so, she responded just like most other seven-year-olds we tested. They didn't need to believe in Princess Alice to see the picture falling as a sign. In fact, if scepticism can be operationally measured by the degree of tilt in rolling eyes, many of them could be called sceptics.
More surprising was that slightly younger children, the credulous five-year-olds, didn't move their hands, and when asked why the picture fell, they said things like "I don't know why she did it, she just did it." They saw Princess Alice as running about making things happen, not as a communicative partner. To them, the events had nothing to do with their behaviour. Finally, the three-year-olds we tested simply shrugged their shoulders and said that the picture was broken. Princess Alice who?

Seeing signs in natural events is a developmental accomplishment rather than the result of a gap in scientific knowledge. To experience an illusion, the psychological infrastructure must first be in place. Whenever I hear mayors blaming hurricanes on drug use or evangelicals attributing tsunamis to homosexuality, I think of Princess Alice. Still, after receiving bad news my first impulse is to ask myself "why?"  Even for someone like me, scientific explanations just don't scratch the itch like supernatural ones. 

Personal Destiny
Jean-Paul Sartre, the atheistic existentialist, observed that he couldn't help but feel as though a divine hand had guided his life. "It contradicts many of my other ideas," he said. "But it is there, floating vaguely. And when I think of myself I often think rather in this way, for want of being able to think otherwise."

My own atheism is not as organic as was Sartre's. Only scientific evidence and eternal vigilance have enabled me to step outside of this particular illusion of personal destiny. Psychologists now know that human beings intuitively reason as though natural categories exist foran intelligently designed purpose. Clouds don't just exist, say kindergartners, they're there for raining.

Erring this way about clouds is one thing, but when it colours our reasoning about our own existence, that's where this teleo-functional bias gets really interesting. The illusion of personal destiny is intricately woven together with other quasi-religious illusions in a complex web that researchers have not even begun to pull apart. My own private thoughts remain curiously saturated with doubts about whether I'm doing what I'm "meant" for.

Some beliefs are arrived at so easily, held so deeply, and divorced so painfully that it seems unnatural to give them up. Such beliefs can be abandoned when the illusions giving rise to them are punctured by scientific knowledge, but a mind designed by nature cannot be changed fundamentally. I stopped believing in God long ago, but he still casts a long shadow.

I used to believe that you could find out what is true by finding the smartest people and finding out what they think. However, the most brilliant people keep turning out to be wrong.  Linus Pauling's ideas about Vitamin C are fresh in mind, but the famous physicist Lord Kelvin did more harm in 1900 with calculations based on the rate of earth's cooling that seemed to show that there had not been enough time for evolution to take place. A lot of the belief that smart people are right is an illusion caused by smart people being very convincing… even when they are wrong.

I also used to believe that you could find out what is true by relying on experts — smart experts — who devote themselves to a topic.  But most of us remember being told to eat margarine because it is safer than butter — then it turned out that trans-fats are worse.  Doctors told women they must use hormone replacement therapy (HRT) to prevent heart attacks — but HRT turned out to increase heart attacks.  Even when they are not wrong, expert reports often don't tell you what is true.  For instance, read reviews by experts about antidepressants; they provide reams of data, but you won't often find the simple conclusion that these drugs are not all that helpful for most patients.  It is not just others; I shudder to think about all the false beliefs I have unknowingly but confidently passed on to my patients, thanks to my trust in experts. Everyone should read the article by Ioannidis, "Why most published research findings are false."

Finally, I used to believe that truth had a special home in universities.  After all, universities are supposed to be devoted to finding out what is true, and teaching students what we know and how to find out for themselves. Universities may be best show in town for truth pursuers, but most stifle innovation and constructive engagement of real controversies, not just sometimes, but most of the time, systematically. 

How can this be? Everyone is trying so hard to encourage innovation!  The Regents take great pains to find a President who supports integrity and creativity, the President chooses exemplary Deans, who mount massive searches for the best Chairs. Those Chairs often hire supporters who work in their own areas, but what if one wants to hire someone doing truly innovative work, someone who might challenge established opinions?  Faculty committees intervene to ensure that most positions go to people just about like themselves, and the Dean asks how much grant overhead funding a new faculty member will bring in.  No one with new ideas, much less work in a new area or critical of established dogmas, can hope to get through this fine sieve.  If they do, review committees are waiting. And so, by a process of unintentional selection, diversity of thought and topic is excluded.  If it still sneaks in, it is purged.  The disciplines become ever more insular. And universities find themselves unwittingly inhibiting progress and genuine intellectual engagement.  University leaders recognize this and hate it, so they are constantly creating new initiatives to foster innovative interdisciplinary work.  These have the same lovely sincerity as new diets for the New Year, and the same blindness to the structural factors responsible for the problems.

Where can we look to find what is true?  Smart experts in universities are a place to start, but if we could acknowledge how hard it is for truth and its pursuers to find safe university lodgings, and how hard it is for even the smartest experts to offer objective conclusions, we could begin to design new social structures that would support real intellectual innovation and engagement.

In 1975, as a newly minted PhD who had just published my first paper on group selection, I was invited by Science magazine to review a book by Michael Gilpin titled Group Selection in Predator Prey Communities. Gilpin was one of the first biologists to appreciate the importance of what Stuart Kauffman would call "the sciences of complexity." In his book, he was claiming that complex interactions could make group selection a more important evolutionary force than the vast majority of biologists had concluded on the basis of more simple mathematical models.

Some background: Group selection refers to the evolution of traits that increase the fitness of whole groups, compared to other groups. These traits are often selectively disadvantageous within groups, creating a conflict between levels of selection. Group selection requires the standard ingredients of natural selection-a population of groups, that vary in their phenotypic properties in a heritable fashion, with consequences for collective survival and reproduction. Standard population genetics models give the impression that groups are unlikely to vary unless they are initiated by small numbers of individuals with minimal migration among groups during their existence. This kind of reasoning turned group selection into a pariah concept in the 1960's , taught primarily as an example of how not to think. I had become convinced that group selection could be revived for smaller, more ephemeral groups that I called "trait groups." Gilpin was suggesting that group selection could also be revived for larger, geographically isolated groups on the basis of complex interactions.

Gilpin focused on the most famous conjecture about group selection, advanced by V.C. Wynne-Edwards in 1962, that animals evolve to avoid overexploiting their resources. Wynne-Edwards had become an icon for everything that was wrong and naïve about group selection. Gilpin boldly proposed that animals could indeed evolve to "manage" their resources, based on non-linearities inherent in predator-prey interactions. As resource exploitation evolves by within-group selection, there is not a gradual increase the probability of extinction. Instead, there is a tipping point that suddenly destabilizes the predator-prey interaction, like falling off a cliff. This discontinuity increases the importance of group selection, keeping the predator-prey interaction in the zone of stability.

I didn't get it. To me, Gilpin's model required a house-of-cards of assumptions, a common criticism leveled against earlier models of group selection. I therefore wrote a tepid review of Gilpin's book. I was probably also influenced by a touch of professional jealousy, as someone who myself was trying to acquire a reputation for reviving group selection!

I didn't get the complexity revolution until I read James Gleik's Chaos: Making A New Science, which I regard as one of the best books ever written about science for a general audience. Suddenly I realized that as complex systems, higher-level biological units such as groups, communities, ecosystems, and human cultures would almost certainly vary in their phenotypic properties and that some of this phenotypic variation might be heritable. Complexity theory became a central theme in my own research.

As one experimental demonstration, William Swenson (then my graduate student) created a population of microbial ecosystems by adding 1 ml of pond water from a single, well-mixed source to test tubes containing 29 ml of sterilized growth medium. This amount of pond water includes millions of microbes, so the initial variation among the test tubes, based on sampling error, was vanishingly small. Nevertheless, within four days (which amounts to many microbial generations) the test tubes varied greatly in their composition and phenotypic properties, such as the degradation of a toxic compound that was added to each test tube. Moreover, when the test tubes were selected on the basis of their properties to create a new generation of microbial ecosystems, there was a response to selection. We could select whole ecosystems for their phenotypic properties (in our case, to degrade a toxic compound), in exactly the same way that animal and plant breeders are accustomed to selecting individual organisms!

These results are mystifying in terms of models that assume simple interactions but make perfect sense in terms of complex interactions. Most people have heard about the famous "butterfly effect" whereby an infinitesimal change in initial conditions becomes amplified over the course of time for a complex physical system such as the weather. Something similar to the butterfly effect was occurring in our experiment, amplifying infinitesimal initial differences among our test tubes into substantial variation over time. A response to selection in the experiments is proof that variation caused by complex interactions can be heritable.

Thanks in large part to complexity theory, evolutionary biologists are once again studying evolution as a multi-level process that can evolve adaptations above the level of individual organisms. I welcome this opportunity to credit Michael Gilpin for the original insight.

Guys lost on unfamiliar streets often avoid asking for directions from locals.  We try to tough it out with map and compass.  Admitting being lost feels like admitting stupidity.  This is a stereotype, but it has a large grain of truth.  It's also a good metaphor for a big overlooked problem in the human sciences. 

We're trying to find our way around the dark continent of human nature.  We scientists are being paid to be the bus-driving tour guides for the rest of humanity.  They expect us to know our way around the human mind, but we don't.

So we try to fake it, without asking the locals for directions.  We try to find our way from first principles of geography ('theory'), and from maps of our own making ('empirical research').  The roadside is crowded with locals, and their brains are crowded with local knowledge, but we are too arrogant and embarrassed to ask the way.  Besides, they look strange and might not speak our language.  So we drive around in circles, inventing and rejecting successive hypotheses about where to find the scenic vistas that would entertain and enlighten the tourists ('lay people', a.k.a. 'tax-payers').  Eventually, our bus-load starts grumbling about tour-guide rip-offs in boring countries.  We drive faster, make more frantic observations, and promise magnificent sights just around the next bend. 

I used to think that this was the best we could do as behavioural scientists.  I figured that the intricacies of human nature were not just dark, but depopulated — that a few exploratory novelists and artists had sought the sources of our cognitive Amazons and emotional Niles, but that nobody actually lived there.

Now, I've changed my mind — there are local experts about almost all aspects of human nature, and the human sciences should find their way by asking them for directions.  These 'locals' are the thousands or millions of bright professionals and practitioners in each of thousands of different occupations.  They are the people who went to our high schools and colleges, but who found careers with higher pay and shorter hours than academic science.  Almost all of them know important things about human nature that behavioural scientists have not yet described, much less understood.  Marine drill sergeants know a lot about aggression and dominance.  Master chess players know a lot about if-then reasoning.  Prostitutes know a lot about male sexual psychology.  School teachers know a lot about child development.  Trial lawyers know a lot about social influence.  The dark continent of human nature is already richly populated with autochthonous tribes, but we scientists don't bother to talk to these experts. 

My suggestion is that whenever we try to understand human nature in some domain, we should identify several groups of people who are likely to know a lot about that domain already, from personal, practical, or professional experience.  We should seek out the most intelligent, articulate, and experienced locals — the veteran workers, managers, and trainers. Then, we should talk with them, face-to-face, expert-to-expert, as collaborating peers, not as researchers 'running subjects' or 'interviewing informants'.  We may not be able to reimburse them at their professional hourly wage, but we can offer other forms of prestige, such as co-authorship on research papers.

For example, suppose a psychology Ph.D. student wants to study emotional adaptations such as fear and panic, that evolved for avoiding predators.  She learns about the existing research (mostly by Clark Barrett at UCLA), but doesn't have any great ideas for her dissertation research.  The usual response is three years of depressed soul-searching, random speculation, and fruitless literature reviews.  This phase of idea-generation could progress much more happily if she just picked up the telephone and called some of the people who spend their whole professional lives thinking about how to induce fear and panic.  Anyone involved in horror movie production would be a good start: script-writers, monster designers, special effects technicians, directors, and editors.  Other possibilities would include talking with:

• Halloween mask designers,
• horror genre novelists,
• designers of 'first person shooter' computer games,
• clinicians specializing in animal phobias and panic attacks,
• Kruger Park safari guides,
• circus lion-tamers,
• dog-catchers,
• bull-fighters,
• survivors of wild animal attacks, and
• zoo-keepers who interact with big cats, snakes, and raptors.

A few hours of chatting with such folks would probably be more valuable in sparking some dissertation ideas than months of library research. 

The division of labor generates wondrous prosperity, and an awesome diversity of knowledge about human nature in different occupations.  Psychology could continue trying to rediscover all this knowledge from scratch.  Or, it could learn some humility, and start listening to the real expertise about human nature already acquired by every bright worker in every factory, office, and mall.

It is a charming concept that humans are in fact able "to change their mind" in the first place. Not that it necessarily implies a change for the better, but at least it does have that positive ring of supposing a Free Will to perform this feat at all. Better, in any case, to be the originator of the changing, rather than having it done to you, in the much less applaudable form of brain washing.

For me, in my own life as I passed the half-century mark, with almost exactly half the time spent in the US and the other in Europe, in-between circling the globe a few times, I can look back on what now seems like multiple lifetimes worth of mind changing.

Here then is a brief point, musing about the field I spent 20 years in: Computer Software. And it is deeper than it may seem at first glance.

I used to think "Software Design" is an art form.

I now believe that I was half-right:
it is indeed an art, but it has a rather short half-life: 
Software is merely a performance art!

A momentary flash of brilliance, doomed to be overtaken by the next wave, or maybe even by its own sequel. Eaten alive by its successors. And time...

This is not to denigrate the genre of performance art: anamorphic sidewalk chalk drawings, Goldsworthy pebble piles or Norwegian carved-ice-hotels are admirable feats of human ingenuity, but they all share that ephemeral time limit: the first rain, wind or heat will dissolve the beauty, and the artist must be well aware of its fleeting glory.

For many years I have discussed this with friends that are writers, musicians, painters and the simple truth emerged: one can still read the words, hear the music and look at the images....

Their value and their appeal remains, in some cases even gain by familiarity: like a good wine it can improve over time. You can hum a tune you once liked, years later. You can read words or look a painting from 300 years ago and still appreciate its truth and beauty today, as if brand new. Software, by that comparison, is more like Soufflé: enjoy it now, today, for tomorrow it has already collapsed on itself. Soufflé 1.1 is the thing to have, Version 2.0 is on the horizon.

It is a simple fact: hardly any of my software even still runs at all!

Back in 1982 I started with a highschool buddy in a garage in the Hollywood hills. With ludicrous limitations we conjured up dreams: three-dimensional charting, displaying sound as time-slice mountains of frequency spectrum data, annotated with perspective lettering... and all that in 32K of RAM on a 0.2Mhz processor. And we did it... a few years later it fed 30 people.

The next level of dreaming up new frontiers with a talented tight team was complex algorithms for generating fractals, smooth color gradients, multi layer bumpmapped textures and dozens of image filters, realtime liquid image effects, and on and on... and that too, worked and this time fed over 300 people. Fifteen products sold many millions of copies - and a few of them still persist to this day, in version 9 or 10 or 11... but for me, I realized, I no longer see myself as a software designer - I changed my mind.

Today, if you have a very large task at hand, one that you calculate might take two years or three... it has actually become cheaper to wait for a couple of generation changes in the hardware and do the whole thing then - ten times faster.

In other words: sit by the beach with umbrella drinks for 15 months and then finish it all at once with some weird beowulf-cluster of machinery and still beat the original team by leaps and bounds. At the start, all we were given was the starting address in RAM where video memory began, and a POKE to FC001101 would put a dot on the screen. Just one dot.

Then you figured out how to draw a line. How to connect them to polygons. How to fill those with patterns. All on a screen of 192x128, ( which is now just "an icon")

Uphill in the snow, both ways.

Now the GPUs are blasting billions of pixels per second and all they will ask is "does it blend?" Pico, Femto, Atto, Zepto, Yocto cycles stored in Giga, Tera, Peta, Exa, Zetta, Yotta cells.

I rest my case about those umbrella drinks.

Do I really just drop all technology and leave computing ? Nahh. QuadHD screens are just around the corner, and as a tool for words, music and images there are fantastic new horizons for me. I am more engaged in it all than ever — alas: the actual coding and designing itself is no longer where I see my contribution. But the point is deeper than just one mans path:

The new role of technology is a serious philosophical point in the long range outlook for mankind. Most decision makers world wide, affecting the entire planet, are technophobes, luddites and noobs beyond belief. They have no vision for the potential, nor proper respect for the risks, nor simple estimation of the immediate value for quality of life that technology could bring. 
Maybe one can change their mind?

I remembered that I once wrote something about this very topic... 
and I found it: 

I changed my mind mostly about changing my mind: 
I used to be all for 'being against it', 
then I was all against 'being for it', 
until I realized: thats the same thing....never mind. 
It's a 'limerickety' little thing from some keynote 12 years ago, but...see.... it still runs : )

I spent a long time believing in the centrality of probability in life and advocating that we should express everything in terms of degrees of credence, with unitary probabilities as a special case for total certainties, and null for total implausibility. Critical thinking, knowledge, beliefs, everything needed to be probabilized. Until I came to realize, twelve years ago, that I was wrong in this notion that the calculus of probability could be a guide to life and help society. Indeed, it is only in very rare circumstances that probability (by itself) is a guide to decision making . It is a clumsy academic construction, extremely artificial, and nonobservable. Probability is backed out of decisions; it is not a construct to be handled in a standalone way in real-life decision-making. It has caused harm in many fields.

Consider the following statement. "I think that this book is going to be a flop. But I would be very happy to publish it." Is the statement incoherent? Of course not: even if the book was very likely to be a flop, it may make economic sense to publish it (for someone with deep pockets and the right appetite) since one cannot ignore the small possibility of a handsome windfall, or the even smaller possibility of a huge windfall. We can easily see that when it comes to small odds, decision making no longer depends on the probability alone. It is the pair probability times payoff (or a series of payoffs), the expectation, that matters. On occasion, the potential payoff can be so vast that it dwarfs the probability — and these are usually real world situations in which probability is not computable.

Consequently, there is a difference between knowledge and action. You cannot naively rely on scientific statistical knowledge (as they define it) or what the epistemologists call "justified true belief" for non-textbook decisions. Statistically oriented modern science is typically based on Right/Wrong with a set confidence level, stripped of consequences. Would you take a headache pill if it was deemed effective at a 95% confidence level? Most certainly. But would you take the pill if it is established that it is "not lethal" at a 95% confidence level? I hope not.

When I discuss the impact of the highly improbable ("black swans"), people make the automatic mistake of thinking that the message is that these "black swans" are necessarily more probable than assumed by conventional methods. They are mostly less probable. Consider that, in a winner-take-all environment such as the one in the arts, the odds of success are low, since there are fewer successful people, but the payoff is disproportionately high. So, in a fat tailed environment, what I call "Extremistan", rare events are less frequent (their probability is lower), but they are so effective that their contribution to the total pie is more substantial.

[Technical note: the distinction is, simply, between raw probability, P[x>K], i.e. the probability of exceeding K, and E[x|x>K], the expectation of x conditional on x>K. It is the difference between the zeroth moment and the first moment. The latter is what usually matters for decisions. And it is the (conditional) first moment that needs to be the core of decision making. What I saw in 1995 was that an out-of-the-money option value increases when the probability of the eventdecreases, making me feel that everything I thought until then was wrong.]

What causes severe mistakes is that, outside the special cases of casinos and lotteries, you almost never face a single probability with a single (and known) payoff. You may face, say, a 5% probability of an earthquake of magnitude 3 or higher, a 2% probability of one of 4 or higher, etc. The same with wars: you have a risk of different levels of damage, each with a different probability. "What is the probability of war?" is a meaningless question for risk assessment.

So it is wrong to just look at a single probability of a single event in cases of richer possibilities (like focusing on such questions as "what is the probability of losing a million dollars?" while ignoring that , conditional on losing more than a million dollars, you may have an expected loss of twenty million, one hundred million, or just one million). Once again, real life is not a casino with simple bets. This is the error that helps the banking system go bust with an astonishing regularity — I've showed that institutions that are exposed to negative black swans, like banks and some classes of insurance ventures, have almost never profitable over long periods. The problem of the illustrative current subprime mess is not so much that the "quants" and other pseudo-experts in bank risk management were wrong about the probabilities (they were), but that they were severely wrong about the different layers of depth of potential negative outcomes. For instance, Morgan Stanley lost about ten billion dollars (so far) while allegedly having foreseen a subprime crisis and executed hedges against it — they just did not realize how deep it would go and had open exposure to the big tail risks. This is routine: a friend who went bust during the crash of 1987, told me: "I was betting that it would happen but I did not know it would go that far".

The point is mathematically simple but does not register easily. I've enjoyed giving math students the following quiz (to be answered intuitively, on the spot). In a Gaussian world, the probability of exceeding one standard deviations is ~16%. What are the odds of exceeding it under a distribution of fatter tails (with same mean and variance)? The right answer: lower, not higher — the number of deviations drops, but the few that take place matter more. It was entertaining to see that most of the graduate students get it wrong. Those who are untrained in the calculus of probability have a far better intuition of these matters.

Another complication is that just as probability and payoff are inseparable, so one cannot extract another complicated component, utility, from the decision-making equation. Fortunately, the ancients with all their tricks and accumulated wisdom in decision-making, knew a lot of that, at least better than modern-day probability theorists. Let us stop to systematically treat them as if they were idiots. Most texts blame the ancients for their ignorance of the calculus of probability — the Babylonians, Egyptians, and Romans in spite of their engineering sophistication, and the Arabs, in spite of their taste for mathematics, were blamed for not having produced a calculus of probability (the latter being, incidentally, a myth, since Umayyad scholars used relative word frequencies to determine authorships of holy texts and decrypt messages). The reason was foolishly attributed to theology, lack of sophistication, lack of something people call the "scientific method", or belief in fate. The ancients just made decisions in a more ecologically sophisticated manner than modern epistemology minded people. They integrated skeptical Pyrrhonian empiricism into decision making. As I said, consider that belief (i.e., epistemology) and action (i.e., decision-making), the way they are practiced, are largely not consistent with one another.

Let us apply the point to the current debate on carbon emissions and climate change. Correspondents keep asking me if it the climate worriers are basing their claims on shoddy science, and whether, owing to nonlinearities, their forecasts are marred with such a possible error that we should ignore them. Now, even if I agreed that it were shoddy science; even if I agreed with the statement that the climate folks were most probably wrong, I would still opt for the most ecologically conservative stance — leave planet earth the way we found it. Consider the consequences of the very remote possibility that they may be right, or, worse, the even more remote possibility that they may be extremely right.

Before I entered the intellectual funnel of graduate school, I used to cook up thought experiments to explain coincidences, such as  running into a person immediately after a random thought of them. This secretive thinking was good mental entertainment, but the demand of forging a serious career in physics research forced me to make peace with such wild speculations.  In my theory of coincidences, non-local interactions as well as a dark form of energy was necessary; absolute science fiction!  Fifteen years later, we now have overwhelming evidence of a 'fifth-force' mediating an invisible substance that the community has dubbed 'dark energy'.   In hindsight, it is of no coincidence that I have changed my mind that nature is non-local. 

Non-local correlations are not common experience to us, thus it is both difficult to imagine and accept.  Often, research in theoretical physics encourages me to keep an open mind; or to not get too attached to ideas that I am deluded into thinking should be correct.   While this has been a constant struggle for me in my scientific career thus far, I have experienced the value of this theoretical ideology weaning process.  After years of wrestling with some of the outstanding problems in the field of elementary particle physics and cosmology, I have been forced to change my mind on this predisposition that has been silently passed on to me by my physics predecessors, that the laws physics are, for the most part, local.

During my first year in graduate school, I came across the famous Einstein, Podosky and Rosen (EPR) thought experiment, which succinctly argue for the inevitable 'spooky action at a distance' in quantum mechanics.   Then came the Aspect experiment that measured the non-local entanglement of photon polarization confirming EPRs expectation that there exist non-local correlations in nature enabled by quantum mechanics (with a caveat of course).   This piece of knowledge had a short life in my education and research career.

Non-locality exited the door of my brain once and for all, after I approached one of my professors, an accomplished quantum field theorist.  He convinced me that non-locality goes away once quantum mechanics properly incorporates causality, through a unification with special relativity; i.e. a theory known as quantum field theory.   With the promise of a sounder career path I invited these, then comforting words, and attempted to master quantum field theory.   Plus, even if non-locality happens, these processes are exceptional events created under special conditions, while most physics is completely local.  Quantum field theory works and it became my new religion.  I have since remained on this comfortable path.

Now that I specialize in the physics of the early universe, I have first hand witnessed the great predictive and precise explanatory powers of Einstein's general relativity, married with quantum field theory to both explain the complete history and physical mechanism for the origin of structures in the universe, all in a seemingly local and causative fashion.  We call this paradigm cosmic inflation and it is deceptively simple.  The universe started out immediately after the big bang from a microscopically tiny piece of space then inflated 'faster than the speed of light'.   Inflation is able to explain our entire complexity of observed universe with the economy of a few equations that involve general relativity and quantum field theory.

Despite its great success inflation has been plagued with conceptual and technical problems.  These problems created thesis projects and inevitably, jobs for a number of young theorists like myself.  Time after time, publication after publication, like a rat on his wheel, we are running out of steam, as the problems of inflation just reappear in some other form.  I have now convinced myself that the problems associated with inflation won't go away unless we somehow include non-locality. 

Ironically, inflation gets ignited by the same form of dark energy that we see permeating the fabric of the cosmos today, except in much greater abundance fourteen billion years ago.  Where did most of the dark energy go after inflation ended?  Why is some of it still around?  Is this omniscient dark energy the culprit behind non-local activity in physical processes?  I don't know exactly how non-locality in cosmology will play itself out, but by its very nature, the physics underlying it will affect 'local' processes.  I still haven't changed my mind on coincidences though.

The appeal of Darwin's theory of evolution — and the horror of it, for some theists — is that it expunges from biology the concept of purpose, of teleology, thereby converting biology into a mechanistic, canonical science. In this respect, the author of The Origin of Species may be said to be the combined Copernicus, Galileo, and Kepler of biology. Just as these astronomers gave us a view of the heavens in which no angels were required to propel the planets in their orbs and the earth was no longer the center of the celestial system, so Darwin showed that no God was needed to design the spider's intricate web and that man is in truth but another animal.

That's how the standard story goes, and it is pretty much what I used to believe, until I read Darwin's later book, his treatise on the evolution of the mental life of animals, including the human species: The Descent of Man. This is the work in which Darwin introduces one of the most powerful ideas in the study of human nature, one that can explain why the capacities of the human mind so extravagantly exceed what would have been required for hunter-gatherer survival on the Pleistocene savannahs. The idea is sexual selection, the process by which men and women in the Pleistocene chose mates according to varied physical and mental attributes, and in so doing "built" the human mind and body as we know it.

In Darwin's account, human sexual selection comes out looking like a kind of domestication. Just as human beings domesticated dogs and alpacas, roses and cabbages, through selective breeding, they also domesticated themselves as a species through the long process of mate selection. Describing sexual selection as human self-domestication should not seem strange. Every direct prehistoric ancestor of every person alive today at times faced critical survival choices: whether to run or hold ground against a predator, which road to take toward a green valley, whether to slake an intense thirst by drinking from some brackish pool. These choices were frequently instantaneous and intuitive and, needless to say, our direct ancestors were the ones with the better intuitions.

However, there was another kind of crucial intuitive choice faced by our ancestors: whether to choose this man or that woman as a mate with whom to rear children and share a life of mutual support. It is inconceivable that decisions of such emotional intimacy and magnitude were not made with an eye toward the character of the prospective mate, and that these decisions did not therefore figure in the evolution of the human personality — with its tastes, values, and interests.  Our actual direct ancestors, male and female, were the ones who were chosen by each other.

Darwin's theory of sexual selection has disquieted and irritated many otherwise sympathetic evolutionary theorists because, I suspect, it allows purposes and intentions back into evolution through an unlocked side door. The slogan memorized by generations of students of natural selection is random mutation and selective retention. The "retention" in natural selection is strictly non-teleological, a matter of brute, physical survival. The retention process of sexual selection, however, is with human beings in large measure purposive and intentional. We may puzzle about whether, say, peahens have "purposes" in selecting peacocks with the largest tails. But other animals aside, it is absolutely clear that with the human race, sexual selection describes a revived evolutionary teleology. Though it is directed toward other human beings, it is as purposive as the domestication of those wolf descendents that became familiar household pets.

Every Pleistocene man who chose to bed, protect, and provision a woman because she struck him as, say, witty and healthy, and because her eyes lit up in the presence of children, along with every woman who chose a man because of his hunting skills, fine sense of humor, and generosity, was making a rational, intentional choice that in the end built much of the human personality as we now know it.

Darwinian evolution is therefore structured across a continuum. At one end are purely natural selective processes that give us, for instance, the internal organs and the autonomic processes that regulate our bodies. At the other end are rational decisions — adaptive and species-altering across tens of thousands of generations in prehistoric epochs.  It is at this end of the continuum, where rational choice and innate intuitions can overlap and reinforce one another, that we find important adaptations that are relevant to understanding the human personality, including the innate value systems implicit in morality, sociality, politics, religion, and the arts. Prehistoric choices honed the human virtues as we now know them: the admiration of altruism, skill, strength, intelligence, industriousness, courage, imagination, eloquence, diligence, kindness, and so forth.

The revelations of Darwin's later work — beautifully explicated as well in books by Helena Cronin, Amotz and Avishag Zahavi, and Geoffrey Miller — have completely altered my thinking about the development of culture. It is not just survival in a natural environment that has made human beings what they are. In terms of our personalities we are, strange to say, a self-made species. For me this is a genuine revelation, as it puts in a new genetic light many human values that have hitherto been regarded as purely cultural.

This was a central part of liberal baby-boomer common sense when I was growing up, especially if you came from a (still) dominant country like Britain. Moreover to show any sense of national feeling — apart from contempt for your national traditions — was a sign that you lacked political sophistication.

I now believe this is mainly nonsense. Nationalism can, of course, be a destructive force and we were growing up in the shadow of its 19th and 20th century excesses. In reaction to that most of the civilized world had, by the mid 20th century, signed up to a liberal universalism (as embodied in the UN charter) that stressed the moral equality of all humans. I am happy to sign up to that too, of course, but I now no longer see that commitment as necessarily conflicting with belief in the nation state. Indeed I think many anti-national liberals make a sort of category error — belief in the moral equality of all humans does not mean that we have the same obligations to all humans. Membership of the political community of a modern nation state places quite onerous duties on us to obey laws and pay taxes, but also grants us many rights and freedoms — and they make our fellow citizens politically "special" to us in a way that citizens of other countries are not. This "specialness" of national citizenship is most vividly illustrated in the factoid that every year in Britain we spend 25 times more on the National Health Service than we do on development aid.

Moreover if the nation state can be a destructive force it is also at the root of what many liberals hold dear: representative democracy, accountability, the welfare state, redistribution of wealth and the very idea of equal citizenship. None of these things have worked to any significant extent beyond the confines of the nation state, which is not to say that they couldn't at some point in the future (indeed they already do so to a small extent in the EU). If you look around at the daily news — contested elections in Kenya, death in Pakistan — most of the bad news these days comes from too little nation state not too much. And why was rapid economic development possible in the Asian tigers but not in Africa? Surely the existence of well functioning nation states and a strong sense of national solidarity in the tigers had something to do with it.

And in rich western countries as other forms of human solidarity — social class, religion, ethnicity and so on — have been replaced by individualism and narrower group identities, holding on to some sense of national solidarity remains more important than ever to the good society. A feeling of empathy towards strangers who are fellow citizens (and with whom one shares history, institutions and social and political obligations) underpins successful modern states, but this need not be a feeling that stands in the way of empathy towards all humans. It just remains true that charity begins at home.

Over the last three years, we've run a project called the Summer of Code, in which we pair up university level software developers with open source software projects. If the student succeeds in fulfilling the goals set forth in their application (which the project has accepted) then they are paid a sum of $4500. We wanted a program that would keep software developers coding over the summer and it would also help out our friends in the world of open source software development.

The passing rate last year was 81%, which means some 700+ students completed their projects to the satisfaction of their mentors.

This last year, we did a cursory study of the code produced by these students and reviewed, among other items, how many lines of code the student produced. The lines of code thing has been done to death in the computer industry, and it's a terrible measure of programmer productivity. It is one of the few metrics we do have and since we make the assumption that if they pass the project then their code has passed muster. So after that the lines of code becomes somewhat more significant than it would normally.

Over the summer of the average student produced 4,000 lines of code with some students producing as much at 10, 14 and even 20 thousand lines. This is an insane amount of code written weather you measure by time or by money. By some measures this means the students are anywhere between 5 and 40 times as productive as your 'average' employed programmer.  This code, mind you, was written by a student who is almost always geographically separated from their mentor by at least 3 time zones and almost never has a face to face meeting with their mentor.

This is an absurd amount of productivity for a student or,  heck, anyone, writing code. This is often production and user-ready code being produced by these students. It's really something to see and made me revise what I consider a productive developer to be and what indeed I should expect from the engineers that work for and with me.

But, and here's the thing I changed my mind about, is the tradeoff for silly high productivity that I have to run my projects the way we run the Summer of Code? Maybe. Can I keep my hands off and let things run their course? Is the team strong enough to act as this kind of mentoring to each other? I now think the answer is that yes, they can run each other better than I can run them. So let's see what letting go looks like. Ask me next year? Let's hope next years question is 'what chance are you least regretful you took?' and I can talk about this then!

I used to think that languages and cultures shape the ways we think. I suspected they shaped they ways we reason and interpret information.  But I didn't think languages could shape the nuts and bolts of perception, the way we actually see the world.  That part of cognition seemed too low-level, too hard-wired, too constrained by the constants of physics and physiology to be affected by language.

Then studies started coming out claiming to find cross-linguistic differences in color memory.  For example, it was shown that if your language makes a distinction between blue and green (as in English), then you're less likely to confuse a blue color chip for a green one in memory.  In a study like this you would see a color chip, it would then be taken away, and then after a delay you would have to decide whether another color chip was identical to the one you saw or not.

Of course, showing that language plays a role in memory is different than showing that it plays a role in perception.  Things often get confused in memory and it's not surprising that people may rely on information available in language as a second resort.  But it doesn't mean that speakers of different languages actually see the colors differently as they are looking at them.  I thought that if you made a task where people could see all the colors as they were making their decisions, then there wouldn't be any cross-linguistic differences.

I was so sure of the fact that language couldn't shape perception that I went ahead and designed a set of experiments to demonstrate this.  In my lab we jokingly referred to this line of work as "Operation Perceptual Freedom."  Our mission: to free perception from the corrupting influences of language.

We did one experiment after another, and each time to my surprise and annoyance, we found consistent cross-linguistic differences.  They were there even when people could see all the colors at the same time when making their decisions.  They were there even when people had to make objective perceptual judgments.  They were there when no language was involved or necessary in the task at all.  They were there when people had to reply very quickly.  We just kept seeing them over and over again, and the only way to get the cross-linguistic differences to go away was to disrupt the language system.  If we stopped people from being able to fluently access their language, then the cross-linguistic differences in perception went away.

I set out to show that language didn't affect perception, but I found exactly the opposite.  It turns out that languages meddle in very low-level aspects of perception, and without our knowledge or consent shape the very nuts and bolts of how we see the world.

I've come to reject the common "SETI" (search for extraterrestrial intelligence) wisdom that there must be millions of technology capable civilizations within our "light sphere" (the region of the Universe accessible to us by electromagnetic communication).  The Drake formula provides a means to estimate the number of intelligent civilizations in a galaxy or in the universe. Essentially, the likelihood of a planet evolving biological life that has created sophisticated technology is tiny, but there are so many star systems, that there should still be many millions of such civilizations. Carl Sagan's analysis of the Drake formula concluded that there should be around a million civilizations with advanced technology in our galaxy, while Frank Drake estimated around 10,000. And there are many billions of galaxies. Yet we don't notice any of these intelligent civilizations, hence the paradox that Fermi described in his famous comment. So where is everyone?

We can readily explain why any one of these civilizations might be quiet. Perhaps it destroyed itself. Perhaps it is following the Star Trek ethical guideline to avoid interference with primitive civilizations (such as ours). These explanations make sense for any one civilization, but it is not credible, in my view, that every one of the billions of technology capable civilizations that should exist has destroyed itself or decided to remain quiet. 

The SETI project is sometimes described as trying to find a needle (evidence of a technical civilization) in a haystack (all the natural signals in the universe). But actually, any technologically sophisticated civilization would be generating trillions of trillions of needles (noticeably intelligent signals). Even if they have switched away from electromagnetic transmissions as a primary form of communication, there would still be vast artifacts of electromagnetic phenomenon generated by all of the many computational and communication processes that such a civilization would need to engage in.  

Now let's factor in what I call the "law of accelerating returns" (the inherent exponential growth of information technology). The common wisdom (based on what I call the intuitive linear perspective) is that it would take many thousands, if not millions of years, for an early technological civilization to become capable of technology that spanned a solar system. But because of the explosive nature of exponential growth, it will only take a quarter of a millennium (in our own case) to go from sending messages on horseback to saturating the matter and energy in our solar system with sublimely intelligent processes.

The price-performance of computation went from 10-5 to 108 cps per thousand dollars in the 20th century. We also went from about a million dollars to a trillion dollars in the amount of capital devoted to computation, so overall progress in nonbiological intelligence went from 10-2 to 1017 cps in the 20th century, which is still short of the human biological figure of 1026 cps. By my calculations, however, we will achieve around 1069 cps by the end of the 21st century, thereby greatly multiplying the intellectual capability of our human-machine civilization.  Even if we find communication methods superior to electromagnetic transmissions we will nonetheless be generating an enormous number of intelligent electromagnetic signals.  

According to most analyses of the Drake equation, there should be billions of civilizations, and a substantial fraction of these should be ahead of us by millions of years. That's enough time for many of them to be capable of vast galaxy-wide technologies. So how can it be that we haven't noticed any of the trillions of trillions of "needles" that each of these billions of advanced civilizations should be creating?

My own conclusion is that they don't exist. If it seems unlikely that we would be in the lead in the universe, here on the third planet of a humble star in an otherwise undistinguished galaxy, it's no more perplexing than the existence of our universe with its ever so precisely tuned formulas to allow life to evolve in the first place.

Recently, I've had to change my mind about the very nature of knowledge because of an obvious, but extremely weird fact about children - they pretend all the time. Walk into any preschool and you'll be surrounded by small princesses and superheroes in overalls - three-year-olds literally spend more waking hours in imaginary worlds than in the real one. Why? Learning about the real world has obvious evolutionary advantages and kids do it better than anyone else. But why spend so much time thinking about wildly, flagrantly unreal worlds? The mystery about pretend play is connected to a mystery about adult humans - especially vivid for an English professor's daughter like me. Why do we love obviously false plays and novels and movies?

The greatest success of cognitive science has been our account of the visual system. There's a world out there sending information to our eyes, and our brains are beautifully designed to recover the nature of that world from that information. I've always thought that science, and children's learning, worked the same way. Fundamental capacities for causal inference and learning let scientists, and children, get an accurate picture of the world around them - a theory. Cognition was the way we got the world into our minds.

But fiction doesn't fit that picture - its easy to see why we want the truth but why do we work so hard telling lies? I thought that kids' pretend play, and grown-up fiction, must be a sort of spandrel, a side-effect of some other more functional ability. I said as much in a review in Science and got floods of e-mail back from distinguished novel-reading scientists. They were all sure fiction was a Good Thing - me too, of course, - but didn't seem any closer than I was to figuring out why.

So the anomaly of pretend play has been bugging me all this time. But finally, trying to figure it out has made me change my mind about the very nature of cognition itself.

I still think that we're designed to find out about the world, but that's not our most important gift. For human beings the really important evolutionary advantage is our ability to create new worlds. Look around the room you're sitting in. Every object in that room - the right angle table, the book, the paper, the computer screen, the ceramic cup was once imaginary. Not a thing in the room existed in the pleistocene. Every one of them started out as an imaginary fantasy in someone's mind. And that's even more true of people - all the things I am, a scientist, a philosopher, an atheist, a feminist, all those kinds of people started out as imaginary ideas too. I'm not making some relativist post-modern point here, right now the computer and the cup and the scientist and the feminist are as real as anything can be. But that's just what our human minds do best - take the imaginary and make it real. I think now that cognition is also a way we impose our minds on the world.

In fact, I think now that the two abilities - finding the truth about the world and creating new worlds-are two sides of the same coins. Theories, in science or childhood, don't just tell us what's true - they tell us what's possible, and they tell us how to get to those possibilities from where we are now. When children learn and when they pretend they use their knowledge of the world to create new possibilities. So do we whether we are doing science or writing novels. I don't think anymore that Science and Fiction are just both Good Things that complement each other. I think they are, quite literally, the same thing.