"What is your heresy?"

I've noticed that the more scientifically educated a person is, the more likely they will harbor a quiet heresy. This is a strongly held belief that goes against the grain of their peers, something not in the accepted cannon of their friends and colleagues. Often the person finds it difficult to fully justify their own belief. It may or may not be believed by others outside their circle, that doesn't matter. What is important is that this view is not held by people they respect and admire. It's become almost a game for me to uncover a person's heresy because I've found that this unconventional view — held with much effort against the tide of their peer's views — tells me more about them than does the bulk of their well-thought out, well-reasoned, and well argued conventional views. The more unexpected the belief is, the more I like them.

Kevin Kelly is Editor-At-Large for Wired Magazine and author of New Rules for the New Economy.

"Universe or multiverse, that is the question?"

Of late, it is fashionable among leading physicists and cosmologists to suppose that alongside the physical world we see lies a stupendous array of alternative realities, some resembling our universe, others very different. The multiverse theory comes in several varieties, but in the most ambitious the "other universes" have different physical laws. Only in a tiny fraction of universes will the laws come out just right, by pure accident, for conscious beings such as ourselves to emerge and marvel at how bio-friendly their world appears.

The multiverse has replaced God as an explanation for the appearance of design in the structure of the physical world. Like God, the agency concerned lies beyond direct observation, inferred by inductive reasoning from the properties of the one universe we do see.

The meta-question is, does the existence of these other universes amount to more than an intellectual exercise? Can we ever discover that the hypothesized alternative universes are really there? If not, is the multiverse not simply theology dressed up in techno jargon? And finally, could there be a Third Way, in which the ingenious features of the universe are explained neither by an Infinite Designer Mind, nor by an Infinite Invisible Multiverse, but by an entirely new principle of explanation.

Paul Davies, a physicist, writer and broadcaster, now based in South Australia, is author of How to Build a Time Machine.

"Why do we ask questions?"

We all take for granted the fact that human beings ask questions and seek explanations, and that the questions they ask go far beyond their immediate practical concerns. But this insatiable human curiosity is actually quite puzzling. No other animal devotes as much time, energy and brain area to the pursuit of knowledge for its own sake. Why? Is this drive for explanation restricted to the sophisticated professional questioners on this site? Or is it a deeper part of human nature?

Developmental research suggests that this drive for explanation is, in fact, in place very early in human life. We've all experienced the endless "whys?" of three-year-olds and the downright dangerous two-year-old determination to seek out strange new worlds and boldly go where no toddler has gone before. More careful analyses and experiments show that children's questions and explorations are strategically designed, in quite clever ways, to get the right kind of answers. In the case of human beings, evolution seems to have discovered that it's cost-effective to support basic research, instead of just funding directed applications. Human children are equipped with extremely powerful learning mechanisms, and a strong intrinsic drive to seek explanations. Moreover, they come with a support staff, — parents and other caregivers — who provide both lunch and references to the results of previous generations of human researchers.

But this preliminary answer prompts yet more questions. Why is it that in adult life, the same quest for explanatory truth so often seems to be satisfied by the falsehoods of superstition and religion? (Maybe we should think of these institutions as the cognitive equivalent of fast food. Fast food gives us the satisfying tastes of fat and sugar that were once evolutionary markers of good food sources, without the nourishment. Religion gives us the illusion of regularity and order, evolutionary markers of truth, without the substance.)

Why does this intrinsic truth-seeking drive seem to vanish so dramatically when children get to school? And, most important, how is it possible for children to get the right answers to so many questions so quickly? What are the mechanisms that allow human children to be the best learners in the known universe? Answering this question would not only tell us something crucial about human nature, it might give us new technologies that would allow even dumb adults to get better answers to our own questions.

Alison Gopnik is a professor of psychology at the University of California at Berkeley and coauthor of The Scientist In The Crib.

"Do we want the God machine?"

The God machine is the name that journalists have given to a device invented by the Canadian psychologist Michael Persinger. It consists of a bunch of solenoids that, when strapped around the head, deliver pulses of electromagnetic radiation to specific regions of the brain. Persinger claims he can induce mystical visions by stimulating the temporal lobes, which have also been linked to religious experiences by other scientists, notably V.S. Ramachandran of the University of California at San Diego.

Persinger's machine is actually quite crude. It induces peculiar perceptual distortions but no classic mystical experiences. But what if, through further advances in neuroscience and other fields, scientists invent a God machine that actually works, that delivers satori, nirvana, to anyone on command, without any negative side effects? It doesn't have to be an electromagnetic brain-stimulating device. It could be a drug, a type of brain surgery, a genetic modification, or some combination thereof.

One psychedelic researcher recently suggested to me that enlightenment could be spread around the world by an infectious virus that boosts the brain's production of dimethyltryptamine, a endogenous psychedelic that the Nobel laureate Julius Axelrod of the National Institutes of Health detected in trace amounts in human brain tissue in 1972. But whatever form the God machine takes, it would be powerful enough to transform the world into what Robert Thurman, an authority on Tibetan Buddhism (and father of Uma), calls the "Buddhaverse," a mystical utopia in which everyone is enlightened.

The obvious followup question: Would the invention of a genuine God machine spell our salvation or doom?

John Horgan is a freelance writer and author of The Undiscovered Mind.

"What kind of system of 'coding' of semantic information does the brain use?"

My question now is actually a version of the question I was asking myself in the first year, and I must confess that I've had very little time to address it properly in the intervening years, since I've been preoccupied with other, more tractable issues. I've been mulling it over in the back of my mind, though, and I do hope to return to it in earnest in 2002.

What kind of system of "coding" of semantic information does the brain use? We have many tantalizing clues but no established model that comes close to exhibiting the molar behavior that is apparently being seen in the brain. In particular, we see plenty of evidence of a degree of semantic localization — neural assemblies over here are involved in cognition about faces and neural assemblies over there are involved in cognition about tools or artifacts, etc — and yet we also have evidence (unless we are misinterpreting it) that shows the importance of "spreading activation," in which neighboring regions are somehow enlisted to assist with currently active cognitive projects. But how could a region that specializes in, say, faces contribute at all to a task involving, say, food, or transportation or . . . . ? Do neurons have two (or more) modes of operation — specialized, "home territory" mode, in which their topic plays a key role, and generalized, "helping hand" mode, in which they work on other regions' topics?

Alternatively, is the semantic specialization we have observed an illusion — are these regions only circumstantially implicated in these characteristic topics because of some as-yet-unanalyzed generalized but idiosyncratic competence that happens to be invoked usually when those topics are at issue? (The mathematician's phone rings whenever the topic is budgets, but he knows nothing about money; he's just good at arithmetic.) Or, to consider another alternative, is "spreading activation" mainly just noisy leakage, playing no contributing role in the transformation of content? Or is it just "political" support, contributing no content but helping to keep competing projects suppressed for awhile? And finally, the properly philosophical question: what's wrong with these questions and what would better questions be?

Daniel C. Dennett is Distinguished Arts and Sciences Professor at Tufts University and author of Darwin's Dangerous Idea.

"'To be or not to be' remains the question"

The fact is that is "To be or not to be" is both a simple, perhaps the simplest, and a complex question, the hardest to sustain, let alone to ask. I ask it myself often — maybe as many times as five or six a week — and it is the asking, not any hope for an answer, that yields the most searing and immediate insight. I don't get it right every time, but when I do, I am thrown for a split second at the other side of being, the place where it begins.

But I can never retain that amazing feeling for long. What is required is a kind of radical pull-back of oneself from the most banal evidence of life and reality. Jean-Paul Sartre, after Shakespeare, was probably the thinker who framed the question best in his novels and philosophical treatises. The issue, however, is that this question is profoundly existential, not merely philosophical. It can be asked and should be by any living, thinking, sentient being, but cannot be answered.

There is huge energy and cognitive release to expect from it when it is properly framed. You have to somehow imagine that everything, absolutely everything has disappeared, or never was, that you have just happened upon your own circumstances by accident, the first accident of being. Another approach is to imagine sharply that anything that is, is a result of a warp, a blip in nothingness. It is not even a matter of finding out why or how, those demands are already far too elaborate. It is a crude, raw, brutal question followed by absolute, lightening speed amazement. And then the ordinary familiarity of all things known and named takes over, slipping your whole being into the stream of life, of being, with its attending problems and felicities. I feel strongly that there is a fundamental need for Shakespeare's question in every day life, but that is not what you and I were taught in school.

Derrick de Kerckhove is Director of the McLuhan Program at the University of Toronto and author of Connected Intelligence.

"Would you choose universe Omega or Upsilon?"

Consider two universes. Universe Omega is a universe in which God does not exist, but the inhabitants of the universe believe God exists. Universe Upsilon is a universe in which God does exist, but no inhabitant believes God exists. In which universe would you prefer to live? In which universe do you think most people would prefer to live?

I recently posed this question to scientists, philosophers, and lay people. Some respondents suggested that if people think God exists, then God is sufficiently "real." A few individuals suggested that people would behave more humanely in a Universe where people believed in God. Yet others countered that an ethical system dependent on faith in a watchful, omniscient, or vengeful God is fragile and prone to collapse when doubt begins to undermine faith. A fuller listing of responses is in the book.

To me, the biggest challenge to answering this question is understanding what is meant by "God." Scientists sometimes think of God as the God of mathematical and physical laws and the underpinnings of the universe. Other people believe in a God who intervenes in our affairs, turns water into wine, answers prayers, and smites the wicked. The Koran implies that God lives outside of time, and, thus, our brains are not up to the task of understanding Him. Some theologians have suggested that only especially sensitive individuals can glimpse God, but us ordinary folk shouldn't deny His existence in the same way that a blind man shouldn't deny the existence of a rainbow. In modern times, many scientists ponder the amazing panoply of chemical and physical constants that control the expansion of the universe and seem tuned to permit the formation of stars and the synthesis of carbon-based life.

Questions about God's omniscience are particularly mind-numbing, yet we can still ask if it is rational to believe in an omniscient God. As Steven J. Brams points out in his book Superior Beings, "The rationality of theistic belief is separate from its truth — a belief need not be true or even verifiable to be rational." However, if we posit the existence of an omniscient God, His omniscience may require him to know the history of all quarks in the universe, the states of all electrons, the vibrations of every string, and the ripples of the quantum foam. Is this the same God, who in Exodus 21 gave Moses laws describing when one should stone an ox to death? Is the God of Gluons and Galaxies the same God concerned with Israeli oxen dung?

But what about the Bible itself? Today, the Bible — especially the Old Testament — may serve as an alternate reality device. It gives its readers a glimpse of other ways of thinking and of other worlds. It is also the most mysterious book ever written. We don't know the ratio of myth to history. We don't know all the authors. We are not always sure of the intended message. We don't fully understand the Old Testament's Nephilim or its Bridegroom of Blood. We only know that that the Bible reflects some of humankind's most ancient and deep feelings. For some unknown reason, it is a bell that has resonated through the centuries. It lets us reach across cultures, see visions, and better understand what we have held sacred. Because the Bible is a hammer that shatters the ice of our unconscious, it thus provides one of many mechanisms in our quest for transcendence.

Clifford A. Pickover is a researcher at IBM's T. J. Watson Research Center and author of The Paradox of God and the Science of Omniscience.

"How are behaviors encoded in DNA?"

Many animals have have quite substantial hereditary behavior. Moreover, these behaviors are subject to evolution on fairly short time scales, so they probably have straightforward DNA encodings on which mutations can act. Mostly the behaviors seem to be sequences of actions, but perhaps there are some of the form "do X until Y is true".

John McCarthy is Professor of Computer Science at Stanford University.

"Why do we tell stories?"

Why a story?

Human beings can't help but understand their world in terms of narratives. Although the theory of evolution effectively dismantled our creationist myths over a century ago, most thinking humans still harbor an attachment to the notion that we were put here, with purpose, by something. New understandings of emergence, as well as new tools for perceiving the order underlying chaos, seem to the hold the promise for a widescale liberation from the constructed myths we use to organize our experience, as well as the dangers that over-dependence on such narratives bring forth. At least I hope so.

At the very least, narratives are less dangerous when we are free to participate in their writing. I'll venture that it is qualitatively better for human beings to take an active role in the unfolding of our collective story than it is to adhere blindly to the testament of our ancestors or authorities.

But what of moving out of the narrative altogether? Is it even possible? Is our predisposition for narrative physiological, psychological, or cultural?

Is it an outmoded form of cognition that yields only bloody clashes when competing myths are eventually mistaken for irreconcilable realities? Or are stories the only way we have of interpreting our world — meaning that the forging of a collective set of mutually tolerant narratives is the only route to a global civilization?

Douglas Rushkoff is a Professor of Media Culture at New York University's Interactive Telecommu-nications Program and author of Coercion: Why We Listen to What "They" Say.

"Eureka: What makes coherence so important to us?"

When something is missing, it bothers us that things don't hang together. Consider: "Give him." In any language, that is a bothersome sentence. Something essential is missing, and it rings an alarm bell in our brains. We go in search of an implied "what" and try to guess what will make the words all hang together into a complete thought.

We ask questions in search of satisfying incompletes, again hoping to create some coherence. No other animal does such things. It even forms the basis of many of our recreations such as jigsaw and crossword puzzles, all those little eurekas along the way.

Guessing a hidden pattern fascinates us. It's part of our pleasure in complex ritual or listening to Bach, to be able to guess what comes next some of the time. It's boring when it is completely predictable, however; it's the search for how things all hang together that is so much fun. Of course, we make a lot of mistakes. Every other winter, I get fooled into thinking that a radio has been left on, somewhere in the house, and I go in search of it — only to realize that it was just the wind whistling around the house. My brain tried to make coherence out of chaos by trying out familiar word patterns on it.

Astrology, too, seems to make lots of things "all hang together." Often in science, we commit such initial errors but we are now fairly systematic about discovering and discarding them. We go on to find much better explanations for how things hang together. Finding coherence is one of our great pleasures. It would be nice to know what predisposes our brain to seek out hidden coherence.

For one thing, it might help illuminate the power of an idea — and with it, how fanaticism works.

Fundamentalist schemes that seem to make everything hang together can easily override civilization's prohibitions against murder. Inferring an enveloping coherence can create an "other" who is outside the bounds of "us." Because it seems so whole, so right, it may become okay to beat up on unbelievers — say, fans of an opposing football team, or of another religion.

For scientists and crossword fans, it's finding the coherence that is important. Then we move on. But many people, especially in the generation which follows its inventors, get trapped by a seemingly coherent worldview. Things get set in concrete; the coherent framework provides comfort, but it also creates dangerous us-and-them boundaries.

William Calvin is a theoretical neurobiologist at the University of Washington and author of How Brains Think.

"Is morality relative or absolute?"

Humans spread out from a common origin into many different global environments. It was a triumph of our unique adaptability, for we display the broadest range of behaviours — nutritional, social, sexual and reproductive – of any animal. We also have classes of behaviour — religious, scientific, artistic, gendered, and philosophical, each underpinned by special languages — that animals lack. Paradoxically, success also came through conformity. Prehistorians track archaeological cultures by recognizing the physical symbolic codes (art styles, burial rites, settlement layouts) that channelled local routines. Each culture constrained diversity and could punish it with ostracism and death. Isolation bred idiosyncracy, and there was a shock when we began regional reintegration. Early empires created state religions which, although sometimes refracting species-wide instincts for a common-good, tended to elevate chosen peoples and their traditional ways.

Now we can monitor all of our cultures there is a need to adjudicate on conduct at a global level. But my question is not understood in the same way by everyone. To fundamentalists, it is heretical, because morality is God-given. Social theorists, on the other hand, often interpret absolute morality as imperialist —no more than local ethics metastasized by (for example) the United Nations. But appeals to protect cultural diversity are typically advanced without regard to the reality of individual suffering in particular communities. A third position, shared by many atheistic scientists and traditional Marxists, is based on ideas of utility, happiness and material truth: what is right is understood as being what is good for the species. But no one agrees on what this is, or how competing claims for access to it should be settled.

The 'ethics of care', first developed within feminist philosophy, moves beyond these positions. Instead of connecting morals either to religious rules and principles or reductive natural laws, it values shared human capacities, such as intimacy, sympathy, trust, fidelity, and compassion. Such an ethics might elide the distinction between relative and absolute by promoting species-wide common sense. Before we judge the prospect of my question vanishing as either optimistic or naïve, we must scrutinize the alternatives carefully.

Timothy Taylor is an archaeologist at University of Bradford, UK, and author of The Prehistory of Sex: Four Million Years of Human Sexual Culture.

"How will the sciences of the mind constrain our theories and policies of education?"

In several recent meetings that I have attended, I have been overwhelmed by the rift between what the sciences of mind, brain and behavior have uncovered over the past decade, and both how and what science educators teach.

In many arenas, educators hold on to a now dated view of the child's cognitive development, failing to appreciate the innate biases that our species has been equipped with. These biases constrain not only what the child can learn, but when it might most profitably learn such things. Take, for instance, the acquisition of mathematical knowledge. Educators aim for the acquisition of precise computations. There is now, however, evidence for an innately available approximate number system, one that operates spontaneously without education.

One might imagine that if educators attempted to push this system first — teaching children that 40 is a better answer to 25 + 12 than is 60 — that it might well facilitate the acquisition of the more precise system later in development. Similar issues arise in attempting to teach children about physics and biology. At some level, then, there must be a way for those in the trenches to work together with those in the ivory tower to advance the process of learning, building on what we have discovered from the sciences of the mind. 

Marc D. Hauser is an evolutionary psychologist, a professor at Harvard University and author of Wild Minds: What AnimalsThink.

"What does it mean to have an educated mind in the 21st century?"

While education is on every politician's agenda as an item of serious importance, it is astonishing that the notion of what it means to be educated never seems to come up. Our society, which is undergoing massive transformations almost on a daily basis never seems to transform its notion of what it means to be educated. We all seem to agree that an educated mind certainly entails knowing literature and poetry, appreciating history and social issues, being able to deal with matters of economics, being versatile in more than one language, understanding scientific principles and the basics of mathematics.

What I was doing in my last sentence was detailing the high school curriculum set down in 1892 by a committee chaired by the President of Harvard that was mandated for anyone who might want to enter a university. The curriculum they decided upon has not changed at all since then. Our implicit notions of an educated mind are the same as they were in the nineteenth century. No need to teach anything new, no need to reconsider how a world where a university education was offered solely to the elite might be different from a world in which a university degree is commonplace.

For a few years, in the early 90's, I was on the Board of Editors of the Encyclopedia Britannica. Most everyone else on the board were octogenarians — the foremost of these, since he seemed to have everyone's great respect, was Clifton Fadiman, a literary icon of the 40's. When I tried to explain to this board the technological changes that were about to come that would threaten the very existence of the Encyclopedia, there was a general belief that technology would not really matter much. There would always be a need for the encyclopedia and the job of the board would always be to determine what knowledge was the most important to have. Only Clifton Fadiman seemed to realize that my predictions about the internet might have some effect on the institution they guarded. He concluded sadly, saying: "I guess we will just have to accept the fact that minds less well educated than our own will soon be in charge."

Note that he didn't say "differently educated," but "less well educated." For some years the literati have held sway over the commonly accepted definition of education. No matter how important science and technology seem to industry or government or indeed to the daily life of the people, as a society we believe that those educated in literature and history and other humanities are in some way better informed, more knowing, and somehow more worthy of the descriptor "well educated."

Now if this were an issue confined to those who run the elite universities and prep schools or those whose bible is the New York Review of Books, this really wouldn't matter all that much to anybody. But this nineteenth century conception of the educated mind weighs heavily on our notions of how we educate our young. We are not educating our young to work or to live in the nineteenth century, or at least we ought not be doing so. Yet, when universities graduate thousands of English and history majors because it can only be because we imagine that such fields form the basis of the educated mind. When we choose to teach our high schoolers trigonometry instead of say basic medicine or business skills, it can only be because we think that trigonometry is somehow more important to an educated mind or that education is really not about preparation for the real world. When we focus on intellectual and scholarly issues in high school as opposed to more human issues like communications, or basic psychology, or child raising, we are continuing to rely upon out dated notions of the educated mind that come from elitist notions of who is to be educated.

While we argue that an educated mind can reason, but curiously there are no courses in our schools that teach reasoning. When we say that an educated mind can see more than one side of an argument we go against the school system which holds that there are right answers to be learned and that tests can reveal who knows them and who doesn't.

Now obviously telecommunications is more important than basic chemistry and HTML is more significant than French in today's world. These are choices that have to be made, but they never will be made until our fundamental conception of erudition changes or until we realize that the schools of today must try to educate the students who actually attend them as opposed to the students who attended them in 1892.

The 21st century conception of an educated mind is based upon old notions of erudition and scholarship not germane to this century. The curriculum of the school system bears no relation to the finished products we seek. We need to rethink what it means to be educated and begin to focus on a new conception of the very idea of education.

Roger Schank is Distinguished Career Professor, School of Computer Science, Carnegie-Mellon University and author of Virtual Learning: A Revolutionary Approach to Building a Highly Skilled Workforce.

"Do the benefits accruing to humankind (leaving aside questions of afterlife) from the belief and practice of organized religions outweigh the costs?"

Given the political sensitivities of the topic, it is hard to imagine that a suitably rigorous attempt to answer this question could be organized or its results published and discussed soberly, but it is striking that there is no serious basis on which to conduct such a conversation. Religion brings peace and solace to many; religion kills people, divides societies, diverts energy and resources. How to assess the net impact in some meaningfully quantitative way? Even to imagine the possibility of such an inquiry and to think through some of the categories you would use could be very enlightening.

James J. O'Donnell is Professor of Classical Studies and Vice Provost at UPenn and author of Avatars of the Word: From Papyrus to Cyberspace.

"Is technology going to 'wake up' or 'come alive' anytime in the future?"

Bill Joy, the prominent computer scientist, argued in a Wired article last year that "the future doesn't need us" because other creatures, artificial or just post-human, are going to take over the world in the 21st century. He is worried that various technologies — particularly robotics, genetic engineering and nanotechnology — are soon going to be capable of generating either a self-conscious machine (something like the Internet "waking up") or one capable of self-replication (nanotechnologists inspired by the vision of Eric Drexler are currently attempting to create a nano-scaled "universal assembler"). If either of these events came to pass, it would surely introduce major changes in the planetary ecology, and humans would have to find a new role to play in such a world. But is Joy right? Do we have to worry about mad scientists producing some invention that inadvertently renders us second-class citizens to machines in the next couple of decades? (Joy is so distraught by this prospect he would have everyone stop working in these areas.)

This is a difficult question to answer, mostly because we don't currently have a very good idea about how technology evolves, so it's hard to predict future developments. But I believe that we can get some way toward an answer by adopting an approach currently being developed by some of our best evolutionary thinkers, such as John Maynard Smith, Eors Szathmary, and others. This "major transition" theory is concerned with determining the conditions under which new kinds of agents emerge in some evolutionary lineage. Examples of such transitions occurred when prokaryotes became eukaryotes, or single-celled organisms became multi cellular. In each case, previously independent biological agents evolved new methods of cooperation, with the result that a new level of organization and agency appeared in the world. This theory hasn't yet been applied to the evolution of technology, but could help to pinpoint important issues. In effect, what I want to investigate is whether the futures that disturb Bill Joy can be appropriately analyzed as major transitions in the evolution of technology. Given current trends in science and technology, can we say that a global brain is around the corner, or that nano-robots are going to conquer the Earth? That, at least, is my current project.

Robert Aunger is an evolutionary theorist and editor of Darwinizing Culture: The Status of Memetics as a Science.

"Was there any choice in the creation of the Universe?"

Here I paraphrase Einstein's famous question: "Did God have any choice in the creation of the Universe". I get rid of the God part, which Einstein only added to make it seem more whimsical, I am sure, because that just confuses the issue. The important question, perhaps the most important question facing physics today is the question of whether there is only one consistent set of physical laws that allow a working universe, or rather whether the constants of nature are arbitrary, and could take any set of values. Namely, if we continue to probe into the structure of matter and the nature of elementary forces will we find that mathematical consistency is possible only for one unique theory of the Universe, or not? In the former case, of course, there is hope for an exactly predictive "theory of everything". In the latter case, we might expect that it is natural that our Universe is merely one of an infinite set of Universes within some grand multiverse, in each of which the laws of physics differ, and in which anthropic arguments may govern why we live in the Universe we do.

The goal of physics throughout the ages has been to explain exactly why the universe is the way it is, but as we push closer and closer to the ultimate frontier, we may find out that in fact the ultimate laws of nature may generically produce a universe that is quite different from the one we live in. This would force a dramatic shift in our concept of natural law.

Some may suggest that this question is mere philosophical nonsense, and is akin to asking how many angels may sit on the head of a pin. However, I think that if we are lucky it may be empirically possible to address it. If, for example, we do come up with some fundamental theory that predicts the values of many fundamental quantities correctly, but that predicts that other mysterious quantities, like the energy of empty space, is generically different than the value we measure, or perhaps is determined probabilistically, this will add strong ammunition to the notion that our universe is not unique, but arose from an ensemble of causally disconnected parts, each with randomly varying values of the vacuum energy.

In any case, answerable or not, I think this is the ultimate question in science.

Lawrence Krauss is Professor of Physics at Case Western Reserve University and the author of Atom.

"How much can we handle?"

We've got fundamental scientific theories (such as quantum theory and relativity) that test out superbly, even if we don't quite know how they all fit into a whole, but we're hung up trying to understand complicated phenomena, like living things. How much complexity can we handle?

We ought to be able to use computers to model complicated things, but we can't as yet write software that's complicated enough to take advantage of the ever-bigger computers we are learning to build.

Complexity, side effects, legacy. How much can we handle? That's the question of the new century.

There's a social variant of the same problem:

In the twentieth century we become powerful enough to destroy ourselves, but we seemed to be able to handle that. Now technology and information flow have improved to the point that a small number of us might be able to destroy us all. Can we handle that?

Jaron Lanier, computer scientist and musician, is currently the lead scientist for the National Tele-Immersion Initiative.

"Why am I me?"

This question was asked by my eight-year-old grandson George. In eight letters it summarizes the conundrum of personal existence in an impersonal universe. How does it happen that a couple of liters of grey matter organizes itself into the unique stream of self-awareness that calls itself George? If we could answer this question, we would be on the way toward an understanding of brain structure and function at a deep level. We would probably have in our hands the key to a more rational and discriminating treatment of mental illnesses. We might also have the key to the design of a genuine artificial intelligence.

Every human being must have asked this question in one way or another. For most of us, the question expresses only a general philosophical curiosity about our place in the order of nature. But for George the question has a more specific technical meaning. He has an identical twin brother Donald, and he understands the distinction between monozygotic and fraternal twins. He knows that he and Donald not only have the same genes but also have the same environment and upbringing. When George asks the question, he is asking how it happens that two people with identical genes and identical nurture are nevertheless different. What are the non-genetic and non-environmental processes in the brain that cause George to be George and cause Donald to be Donald? If we could answer this question, we would have a powerful new tool for the investigation of cognitive development. The conventional wisdom says that mental differences between George and Donald arise from local randomness of neural connections, undetermined either by genes or by sensory input. But to say that the connections are random only means that we do not yet understand how they came about.

Freeman Dyson is professor of physics at the Institute for Advanced Study and author of The Sun, the Genome, and the Internet.

"Do we want to live in one world, or two?"

One of the great achievements of recent history has been a dramatic reduction in absolute poverty in the world. In 1820 about 85% of the world's population lived on the equivalent of a dollar a day (converted to today's purchasing power). By 1980, that percentage had dropped to 30%, but it is now down to 20%.

But that still means 1 billion people live in absolute poverty. A further 2 billion are little better off, living on $2 a day. A quarter of the world's people never get a cup of clean water.

Part of what globalisation means is that we have a reasonable chance of assuring that a majority of the world's people will benefit from continuing economic growth, improvements in health and education, and the untapped potential of the extraordinary technologies about which most of the Edge contributors write so eloquently.

We currently lack the political will to make sure that a vast number of people are not fenced off from this optimistic future. So my question poses a simple choice. Are we content to have two, increasingly estranged world? Or do we want to find the path to a unified, healthy world?

Lance Knobel is Adviser, Prime Minister's Forward Strategy Unit, London, and the former head of the program of the World Economic Forums' Annual meeting in Davos.

"What's the neurobiology of doing good and being good?"

I've spent most of my career as a neurobiologist working on an area of the brain called the hippocampus. It's a fairly useful region — it plays a critical role in learning and memory. It's the area that's damaged in Alzheimer's, in alcoholic dementia, during prolonged seizures or cardiac arrest. You want to have your hippocampus functioning properly. So I've spent all these years trying to figure out why hippocampal neurons die so easily and what you can do about it. That's fine, might even prove useful some day. But as of late, it's been striking me that I'm going to be moving in the direction of studying a part of the brain called the prefrontal cortex (PFC).

It's a fascinating part of the brain, the part of the brain that most defines us as humans. There's endless technical ways to describe what the PFC does, but as an informal definition that works pretty well, it's the closest thing we have to a superego. The PFC is what allows us to become potty trained early on. And it is responsible for squeezing our psychic sphincters closed as well. It keeps us from belching loudly at the quiet moment in the wedding ceremony, prevents us from telling our host just what we really think of the inedible meal they've served. It keeps us from having our murderous thoughts turn into murderous acts. And it plays a similar role in the cognitive realm — the PFC stops us from falling into solving a problem with an answer that, while the easier, more reflexive one, is wrong. The PFC is what makes us do the right thing, even if it's harder.

Not surprisingly, it's one of the last parts of the brain to fully develop (technical jargon — to fully myelinate). But what is surprising is just how long it is before the PFC comes fully on line — astonishingly, around age 30. And this is where my question comes in. It is best framed in the context of young kids, and this is probably what has prompted me to begin to think about the PFC, as I have two young children. Kids are wildly "frontally disinhibited," the term for having a PFC that hasn't quite matured yet into keeping its foot firmly on the brake. Play hide and seek with a three year old, loudly, plaintively call, "Where are you," and their lack of frontal function does them in — they can't stop themselves from calling out — Here I am, under the table — giving away their hiding spot. I suspect that there is a direct, near linear correlation between the number of fully myelinated frontal neurons in a small child's brain and how many dominoes you can line up in front of him before he must MUST knock them over.

So my question comes to the forefront in a scenario that came up frequently for me a few years ago: my then three year old who, while a wonderful child, was distinctly three, would do something reasonably appalling to his younger sister — take some stuffed animal away, grab some contested food item, whatever. A meltdown then ensues. My wife or I intervene, strongly reprimanding our son for mistreating his sister. And then the other parent would say, "Well, is this really fair to be coming down on him like this?, after all, he has no frontal function yet, he can't stop himself" (my wife is a neuropsychologist so, pathetically, we actually speak this way to each other). And the other would retort — "Well, how else is he going to develop that frontal function?"

That's the basic question — how does the world of empathy, theory of mind, gratification postponement, Kohlberg stages of moral development, etc., combine with the world of neurotrophic growth factors stimulating neurons to grow fancier connections? How do they produce a PFC that makes you do the harder thing because it's right? How does this become a life-long pattern of PFC function

Robert Sapolsky is a professor of biological sciences at Stanford University and author of A Primate's Memoir.

"Is humanity in the midst of a cognitive 'Fourth-Transition?' Or, why doesn't the Encyclopedia Brittanica matter any more?"

It feels to me like something very important is going on. Clearly our children aren't quite like us. They don't learn about the world as we did. They don't storehouse knowledge about the world as we have. They don't "sense" the world as we do. Could humanity possibly already be in the middle of a next stage of cognitive transition?

Merlin Donald has done a fine job of summarizing hundreds of inquiries into the evolution of culture and cognition in his Origins of the Modern Mind. Here, as in his other work, he posits a series of "layered" morphological, neurological and external technological stages in this evolutionary path. What he refers to as the "Third Transition" (from "Mythic" to "Theoretic" culture), appears to have begun 2500 (or so) years ago and has now largely completed its march to "mental" dominance worldwide.

While this last "transition" did not require biological adaptation (or speciation), it nonetheless changed us — neurologically and psycho-culturally. The shift from the "primary orality" of "Mythic culture" to the literacy and the reliance of what Donald calls an "External Symbolic Storage" network, has resulted in a new sort of mind. The "modern" mind.

Could we be "evolving" towards an even newer sort of mind as a result of our increasing dependence on newer sorts of symbolic networks and newer environments of technologies?

Literacy (while still taught and used) doesn't have anywhere near the clout it once had. Indeed, as fanatical "literalism" (aka "fundamentalism") thrashes its way to any early grave (along with the decline of the reciprocal fascination of the past 50 years to "deconstruct" everything as "texts"), how much will humanity care about and rely upon the encyclopedic storage of knowledge in alphabetic warehouses?

Perhaps we are already "learning," "knowing" and "sensing" the world in ways that presage something very different from the "modern" mind. Should we ask the children?

Mark Stahlman, a venture capitalist who has been focused on next generation computer/networking platforms, is co-founder the Newmedia Laboratory, NYNMA.

"What are minds, that they are both essentially mental yet inextricably intertwined with body (and world)?"

We thought we had this one nailed. Believing (rightly) that the physical world is all there is, the sciences of the mind re-invented thought and reason (and feeling) as information-processing events in the human brain. But this vision turns out to be either incomplete or fatally flawed. The neat and tidy division between a level of information processing (software) and of physicality (implementation) is useful when we deal with humanly engineered systems. We build such systems, as far as possible, to keep the levels apart. But nature was not guided by any such neat and tidy design principles. The ways that evolved creatures solve problems of anticipation, response, reasoning and perceiving seem to involve endless leakage and interweaving between motion, action, visceral (gut) response, and somewhat more detached contemplation. When we solve a jigsaw puzzle, we look, think, and categorise: but we also view the scene and pieces from new angles, moving head and body. And we pick pieces up and try them out. Real on-the-hoof human reason is like that through and through. Even the use of pen and paper to construct arguments displays the same complex interweaving of embodied action, perceptual re-encountering, and neural activity. Mind and body (and world) emerge as messily and continuously coupled partners in the construction of rational action.

But this leads to a very real problem, an impasse that is currently the single greatest roadblock in the attempts to construct a mature science of the mind. We cannot, despite the deep and crucial roles of body and world, understand the mind in quite the same terms as, say, an internal combustion engine. Where minds are concerned, it is the flow of contents (and feelings) that seems to matter. Yet if we prescind from the body and world, pitching our stories and models at the level of the information flows, we again lose sight of the distinctively human mind. We need the information-and-content based story to see the mind as, precisely, a mind. Yet we cannot do justice to minds like ours without including body, world (cognitive tools and other people) and motion in roles which are both genuinely cognitive yet thoroughly physical.

What we lack is a framework, picture, or model in terms of which to understand this larger system as the cognitive engine. All current stories are forced to one side (information flows) or the other (physical dynamics). Cognitive Science thus stands in a position similar to that of Physics in the early decades of the 20th century. What we lack is a kind of 'quantum theory' of the mind: a new framework that displays mind as mind, yet as body in action too.

Andy Clark is Professor of Philosophy and Cognitive Science at the University of Sussex, UK and the author of Being There: Putting Brain, Body and World Together Again.

"At what age should women say, 'No,' to first-time pregnancy?"

Scientific advances now make it possible for a woman past normal child-bearing years to bear a child. Some of my high-tech friends who range from age 43 to almost 50 are either bearing children or plan to using in-vitro techniques. These women have postponed childbearing because of their careers, but they want to experience the joys of family that their male counterparts were able to share while still pursuing their professional goals — an option far more difficult for the childbearer and primary care provider.

Many successful men start first, second, or third families later in their lives, so why should we criticize women who want to bear a first child, when, thanks to science, it is no longer "too late?"

Sylvia Paull is the founder of Gracenet (www.gracenet.net).

"What is the relationship between being alive and having a mind?"

Last year, Steven Spielberg directed a film, based upon a Stanley Kubrick project, entitled "A.I. Artificial Intelligence". The film depicts a robotic child who develops human emotions. Is such a thing possible? Could a sufficiently complex and appropriately designed computer embody human emotions? Or is this simply a fanciful notion that the public and some scientists who specialize in artificial intelligence just wish could be true?

I don’t think that computers will ever become conscious and I view Spielberg’s depiction of a conscious feeling robot a good example of what might be called the "The Spielberg Principle" that states: When a Steven Spielberg film depicts a world-changing scientific event, the likelihood of that event actually occurring approaches zero." In other words, our wishes and imagination often have little to do with what is scientifically likely or possible. For example, although we might wish for contact with other beings in the universe as portrayed in the Spielberg movie "E.T", the astronomical distances between our solar system and the rest of the universe makes an E.T.-like visit extremely unlikely.

The film A.I. and the idea contained within it that robots could someday become conscious is another case in which our wishes exceed reality. Despite enormous advances in artificial intelligence, no computer is able to experience a pin prick like a simple frog, or get hungry like a rat, or become happy or sad like all of us carbon-based units. But why is this the case? It is my conjecture that this is because there are some features of being alive that makes mind, consciousness, and feelings possible. That is, only living things are capable of the markers of mind such as intentionality, subjectivity, and self-awareness. But the important question of the link between life and the creation of consciousness remains a great scientific mystery, and the answer will go a long way toward our understanding of what a mind actually is.

Todd E. Feinberg, MD is Chief, Yarmon Neurobehavior and Alzheimer's Disease Center, Beth Israel Medical Center

"To be or not to be?"

Old questions don't go away (at least while they remain unanswered). Suppose Edge were to have asked Hamlet for his Y 2002 question We can guess the answer. "Sorry, John, I know it's a bit of a cliché, but it's the same question it has always been." Suppose Edge turned next to Albert Camus. "John, I said it in 1942 and I'm still waiting. 'There is but one truly serious philosophical problem and that is suicide. Judging whether life is or is not worth living amounts to answering the fundamental question of philosophy. All the rest — whether or not the world has three dimensions, whether the mind has nine or twelve categories — comes afterwards.'"

Clichés they may be.  But I'd say there's every reason for students of human nature to continue to treat these questions with due seriousness: and in particular to think further about who has been asking them,  when, and why, and with what consequences.  It may seem a paradox that human beings should have evolved to have a love-hate relationship with their own existence. But in fact there may be a simple Darwinian story to be told about how it has come to be  so.

Let's accept the stark truth that individual human beings have been designed by natural selection to be, in Dawkins' famous phrase, "survival machines" whose primary function is to help the genes they carry to make it into future generations. We should admit, then, that, from this evolutionary viewpoint, an  individual human life cannot be considered an end in itself but only a means to promoting the success of genes.

Yet the fact is that in the human case (and maybe the human case alone) natural selection has devised a peculiarly effective trick  for persuading individual survival machines to fulfill this seemingly bleak role. Every human being is endowed  with the mental programs for developing a "conscious self" or "soul": a soul which not only  values its own survival but  sees itself as very much an end in its own right  (in fact a soul which, in a fit of solipsism,  may even consider itself the one and only source of all the ends there are!). Such  a soul, besides doing all it can to ensure its own basic comfort and security, will typically strive for self-development: through learning, creativity, spiritual growth, symbolic expression,  consciousness-raising, and so on. These activities redound to the advantage of mind and body. The result is that such "selfish souls" do indeed make wonderful agents for "selfish genes".

There has, however,  always been a catch.  Naturally-designed "survival machines" are not, as the name might imply machines designed to go on and on surviving: instead they are machines designed to survive only up to a point —  this  being the point where the genes they carry have nothing more to gain (or even things to lose) from continued life.  For it"s a sobering fact that genes are generally  better off taking passage and propagating themselves in younger machines than older ones (the older ones will have begun to accumulate defects, to have become set in their ways, to have acquired more than enough dependents, etc.) It suits  genes therefore that their survival machines should have a limited life-time, after which they can be scrapped. 

Thus,  in a scenario that has all the makings of tragedy (if not a tragic farce),  natural selection has, on the one hand,  been shaping up individual human beings at the level of their souls to believe in themselves and their intrinsic worth, while on the other hand taking steps to ensure that these same individuals on the level of their bodies grow old and die —  and, most likely, since by this stage of a life the genes no longer have any interest in preventing it,  to die miserably, painfully and in a state of dreadful disillusion.

However,  here's the second catch. In order for this double-game that the genes are playing to be successful, it's essential that the soul they've designed does not see what's coming and realise the extent to which it has been duped, at least until too late. But this means preventing the soul, or at any rate cunningly diverting it,  from following some of the very lines of inquiry on which it has been set up  to place its hopes: looking to the future, searching for eternal truths, and so on. In Camus' words "Beginning to think is beginning to be undermined".

The history of human psychology and culture has revolved around this contradiction built into human nature. Science has not had much to say about it. But it may yet.

Nicholas Humhprey is a theoretical psychologist at the London School of Economics, and author of Leaps of Faith.

"Why Sleep?"

We need to sleep every day. Why do we spend a third of our lives in a dormant state? Sleep deprivation leads to loss of judgment, failure of health, and eventually to death. The cycle of sleep and alertness is controlled by circadian rhythms, which also affect body temperature, digestion and other regulatory systems. Despite the importance of sleep its purpose is a mystery.

The brain remains highly active during sleep, so the simple explanation that we sleep in order to rest cannot be the whole story. Activity in the sleeping brain is largely hidden from us because very little that occurs during sleep directly enters consciousness. However, electrical recordings and more recently brain imaging experiments during slow-wave sleep have revealed highly ordered patterns of activity that are much more spatially and temporally coherent than brain activity during states of alertness. Slow-wave sleep alternates during the night with rapid eye sleep movement (REM) sleep, during which dreams occur and muscles are paralyzed. For the last 10 years my colleagues and I have been building computer models of interacting neurons that can account for rhythmic brain activity during sleep.

Computer models of the sleeping brain and recent experimental evidence point toward slow-wave sleep as a time during which brain cells undergo extensive structural reorganization. It takes many hours for the information acquired during the day to be integrated into long-term memory through biochemical reactions. Could it be that we go to sleep every night in order to remember better and think more clearly?

Introspection is misleading in trying to understand the brain in part because much of the processing that takes place to support seeing, hearing and decision-making is subconscious. In studying the brain during sleep when we are aware of almost nothing, we may get a better understanding of the brain’s secret life and uncover some of the elusive principles that makes the mind so illusive.

Terrence Sejnowski, a computational neurobiologist and Professor at the Salk Institute for Biological Studies, is a coauthor of Thalamocortical Assemblies: How Ion Channels, Single Neurons and Large-Scale Networks Organize Sleep Oscillations.

"What makes a genius, and how can we have more of them?"

As any software developer will tell you, one great programmer is easily worth ten average ones. The great strides in knowledge have most often come from those we label "genius." Newton, Gauss, Einstein, Feyneman, de Morgan, Crick all seemed to be able to make connections or see patterns that others had ignored. They often visualized the world differently, or with fewer constraints than most of us have on our imagination. There are many great problems of science and society to be solved, and applying genius to them could help speed the solutions.

Perhaps the analysis of Einstein's brain done by Professor Diamond at Berkeley, which seems to show differences in structure in the inferior parietal region, and a higher proportion of glial cells can lead to some physiological answers. Perhaps there are chemical enhancers which can be used (legally, one would hope), to increase oxygen flow to neurons. Perhaps behavioral conditioning when we're young can help create more of the right type of structures, just as musicians who being training in early childhood have larger portions of the brain devoted to their skills.

Whatever the answer, mankind might be better for some more genius directed at the environmental, social and scientific fields.

Howard Morgan is Vice-Chairman, Idealab.

"Why do people — even identical twins — differ from one another in personality?"

This question needs to be asked because of the widely held conviction that we already know the answer to it. We don't. Okay, we know half of the answer: one of the reasons why people differ from each other is that they have different genes. That's the easy half.

The hard half is the part that isn't genetic. Even people who have identical genes, like Freeman Dyson's twin grandsons (see his question), differ in personality. I am not asking about the feeling each twin has of being "me": George and Donald could be identical in personality, and yet each could have a sense of me-ness.

But if George and Donald are like most identical twins, they aren't identical in personality. Identical twins are more alike than fraternal twins or ordinary siblings, but less alike than you would expect. One might be more meticulous than the other, or more outgoing, or more emotional. The weird thing is that the degree of similarity is the same, whether twins are reared together or apart. George and Donald, according to their grandfather, "not only have the same genes but also have the same environment and upbringing." And yet they are no more alike in personality than twins reared by two different sets of parents in two different homes.

We know that something other than genes is responsible for some of the variation in human personality, but we are amazingly ignorant about what it is and how it works. Well-designed research has repeatedly failed to confirm commonly held beliefs about which aspects of a child's environment are important. The evidence indicates that neither those aspects of the environment that siblings have in common (such as the presence or absence of a caring father) nor those that supposedly widen the differences between siblings (such as parental favoritism or competition between siblings) can be responsible for the non-genetic variation in personality. Nor can the vague idea of an "interaction" between genes and environment save the day. George and Donald have the same genes, so how can an interaction between genes and environment explain their differences?

Only two hypotheses are compatible with the existing data. One, which I proposed in my book The Nurture Assumption, is that the crucial experiences that shape personality are those that children have outside their home. Unfortunately, there is as yet insufficient evidence to support (or disconfirm) this hypothesis.

The remaining possibility is that the unexplained variation in personality is random. Even for reared-together twins, there are minor, random differences in their experiences. I find it
implausible, however, that minor, random differences in experiences could be so potent, given the ineffectiveness of substantial, systematic differences. If randomness affects personality, the way it probably works is through biological means — not genetic but biological. The human genome is smallish and the human brain is vast; the genome couldn't possibly contain precise specifications for every neuron and synapse. Identical twins don't have identical brains for the same reason that they don't have identical freckles or fingerprints.

If these random physical differences in the brain are responsible for some or all of the personality differences between identical twins, they must also be responsible for some or all of the non-genetic variation in personality among the rest of us. "All" is highly unlikely; "some" is almost certainly true. What remains in doubt is not whether, but how much.

The bottom line is that scientists will probably never be able to predict human behavior with anything close to certainty. Next question: Is this discouraging news or cause for celebration?

Judith Rich Harris is a developmental psychologist and author of The Nurture Assumption: Why Children Turn Out The Way They Do.

"Many Universes?"

Preliminaries

We do not know whether there are other universes. Perhaps we never shall. But I want to respond to Paul Davies' questions by arguing that "do other universes exist?" can be a genuine scientific question. Moreover, I shall outline why it is an interesting question; and why, indeed, I already suspect that the answer may be "yes".

First, a pre-emptive and trivial comment: if you define the universe as "everything there is", then by definition there cannot be others. I shall, however, follow the convention among physicists and astronomers, and define the "universe" as the domain of space-time that encompasses everything that astronomers can observe. Other "universes", if they existed, could differ from ours in size, content, dimensionality, or even in the physical laws governing them.

It would be neater, if other "universes" existed, to redefine the whole enlarged ensemble as "the universe", and then introduce some new term — for instance "the metagalaxy" — for the domain that cosmologists and astronomers have access to. But so long as these concepts remain so conjectural, it is best to leave the term "universe" undisturbed, with its traditional connotations, even though this then demands a new word, the "multiverse", for a (still hypothetical) ensemble of "universes."

Ontological Status Of Other Universes

Science is an experimental or observational enterprise, and it's natural to be troubled by assertions that invoke something inherently unobservable. Some might regard the other universes as being in the province of metaphysics rather than physics. But I think they already lie within the proper purview of science. It is not absurd or meaningless to ask "Do unobservable universes exist?", even though no quick answer is likely to be forthcoming. The question plainly can't be settled by direct observation, but relevant evidence can be sought, which could lead to an answer.

There is actually a blurred transition between the readily observable and the absolutely unobservable, with a very broad grey area in between. To illustrate this, one can envisage a succession of horizons, each taking us further than the last from our direct experience:

(i) Limit of present-day telescopes

There is a limit to how far out into space our present-day instruments can probe. Obviously there is nothing fundamental about this limit: it is constrained by current technology. Many more galaxies will undoubtedly be revealed in the coming decades by bigger telescopes now being planned. We would obviously not demote such galaxies from the realm of proper scientific discourse simply because they haven't been seen yet. When ancient navigators speculated about what existed beyond the boundaries of the then known world, or when we speculate now about what lies below the oceans of Jupiter's moons Europa and Ganymede, we are speculating about something "real" — we are asking a scientific question. Likewise, conjectures about remote parts of our universe are genuinely scientific, even though we must await better instruments to check them.

(ii) Limit in principle at present era

Even if there were absolutely no technical limits to the power of telescopes, our observations are still bounded by a horizon, set by the distance that any signal, moving at the speed of light, could have travelled since the big bang. This horizon demarcates the spherical shell around us at which the redshift would be infinite. There is nothing special about the galaxies on this shell, any more than there is anything special about the circle that defines your horizon when you're in the middle of an ocean. On the ocean, you can see farther by climbing up your ship's mast. But our cosmic horizon can't be extended unless the universe changes, so as to allow light to reach us from galaxies that are now beyond it. If our universe were decelerating, then the horizon of our remote descendants would encompass extra galaxies that are beyond our horizon today. It is, to be sure, a practical impediment if we have to await a cosmic change taking billions of years, rather than just a few decades (maybe) of technical advance, before a prediction about a particular distant galaxy can be put to the test. But does that introduce a difference of principle? Surely the longer waiting-time is a merely quantitative difference, not one that changes the epistemological status of these faraway galaxies?

(iii) Never-observable galaxies from "our" Big Bang,

But what about galaxies that we can never see, however long we wait? It's now believed that we inhabit an accelerating universe. As in a decelerating universe, there would be galaxies so far away that no signals from them have yet reached us; but if the cosmic expansion is accelerating, we are now receding from these remote galaxies at an ever-increasing rate, so if their light hasn't yet reached us, it never will. Such galaxies aren't merely unobservable in principle now — they will be beyond our horizon forever. But if a galaxy is now unobservable, it hardly seems to matter whether it remains unobservable for ever, or whether it would come into view if we waited a trillion years. (And I have argued, under (ii) above, that the latter category should certainly count as "real".)

(iv) Galaxies in disjoint universes

The never-observable galaxies in (iii) would have emerged from the same Big Bang as we did. But suppose that, instead of causally-disjoint regions emerging from a single Big Bang (via an episode of inflation) we imagine separate Big Bangs. Are space-times completely disjoint from ours any less real than regions that never come within our horizon in what we'd traditionally call our own universe? Surely not — so these other universes too should count as real parts of our cosmos, too.

This step-by-step argument (those who don't like it might dub it a slippery slope argument!) suggests that whether other universes exist or not is a scientific question. But it is of course speculative science. The next question is, can we put it on a firmer footing? What could it explain?

Scenarios For A Multiverse

At first sight, nothing seems more conceptually extravagant — more grossly in violation of Ockham's Razor — than invoking multiple universes. But this concept is a natural consequence of several different theories ( albeit all speculative). Andrei Linde, Alex Vilenkin and others have performed computer simulations depicting an "eternal" inflationary phase where many universes sprout from separate big bangs into disjoint regions of spacetimes. Alan Guth and Lee Smolin have, from different viewpoints, suggested that a new universe could sprout inside a black hole, expanding into a new domain of space and time inaccessible to us. And Lisa Randall and Raman Sundrum suggest that other universes could exist, separated from us in an extra spatial dimension; these disjoint universes may interact gravitationally, or they may have no effect whatsoever on each other.

There could be another universe just a few millimetres away from us. But if those millimetres were measured in some extra spatial dimension then to us (imprisoned in our 3-dimensional space) the other universe would be inaccessible. In the hackneyed analogy where the surface of a balloon represents a two-dimensional universe embedded in our three-dimensional space, these other universes would be represented by the surfaces of other balloons: any bugs confined to one, and with no conception of a third dimension, would be unaware of their counterparts crawling around on another balloon. Variants of such ideas have been developed by Paul Steinhardt, Neil Turok and others. Guth and Edward Harrison have even conjectured that universes could be made in some far-future laboratory, by imploding a lump of material to make a small black hole. Could our entire universe perhaps then be the outcome of some experiment in another universe? If so, the theological arguments from design could be resuscitated in a novel guise. Smolin speculates that the daughter universe may be governed by laws that bear the imprint of those prevailing in its parent universe. If that new universe were like ours, then stars, galaxies and black holes would form in it; those black holes would in turn spawn another generation of universes; and so on, perhaps ad infinitum.

Parallel universes are also invoked as a solution to some of the paradoxes of quantum mechanics, in the "many worlds" theory, first advocated by Hugh Everett and John Wheeler in the 1950s. This concept was prefigured by Olaf Stapledon, in his 1937 novel, as one of the more sophisticated creations of his Star Maker: "Whenever a creature was faced with several possible courses of action, it took them all, thereby creating many ... distinct histories of the cosmos. Since in every evolutionary sequence of this cosmos there were many creatures and each was constantly faced with many possible courses, and the combinations of all their courses were innumerable, an infinity of distinct universes exfoliated from every moment of every temporal sequence". None of these scenarios has been simply dreamed up out of the air: each has a serious, albeit speculative, theoretical motivation. However, one of them, at most, can be correct. Quite possibly none is: there are alternative theories that would lead just to one universe. Firming up any of these ideas will require a theory that consistently describes the extreme physics of ultra-high densities, how structures on extra dimensions are configured, etc. But consistency is not enough: there must be grounds for confidence that such a theory isn't a mere mathematical construct, but applies to external reality. We would develop such confidence if the theory accounted for things we can observe that are otherwise unexplained. As the moment, we have an excellent framework, called the standard model, that accounts for almost all subatomic phenomena that have been observed. But the formulae of the "standard model" involve numbers which can't be derived from the theory but have to be inserted from experiment.

Perhaps, in the 21st-century theory, physicists will develop a theory that yields insight into (for instance) why there are three kinds of neutrinos, and the nature of the nuclear and electric forces. Such a theory would thereby acquire credibility. If the same theory, applied to the very beginning of our universe, were to predict many big bangs, then we would have as much reason to believe in separate universes as we now have for believing inferences from particle physics about quarks inside atoms, or from relativity theory about the unobservable interior of black holes.

Universal Laws, Or Mere Bylaws?

"Are the laws of physics unique?" is a less poetic version of Einstein's famous question "Did God have any choice in the creation of the Universe?" The answer determines how much variety the other universes — if they exist — might display. If there were something uniquely self-consistent about the actual recipe for our universe, then the aftermath of any big bang would be a re-run of our own universe. But a far more interesting possibility (which is certainly tenable in our present state of ignorance of the underlying laws) is that the underlying laws governing the entire multiverse may allow variety among the universes. Some of what we call "laws of nature" may in this grander perspective be local bylaws, consistent with some overarching theory governing the ensemble, but not uniquely fixed by that theory.

As an analogy (one which I owe to Paul Davies) consider the form of snowflakes. Their ubiquitous six-fold symmetry is a direct consequence of the properties and shape of water molecules. But snowflakes display an immense variety of patterns because each is moulded by its micro-environments: how each flake grows is sensitive to the fortuitous temperature and humidity changes during its downward drift. If physicists achieved a fundamental theory, it would tell us which aspects of nature were direct consequences of the bedrock theory (just as the symmetrical template of snowflakes is due to the basic structure of a water molecule) and which are (like the distinctive pattern of a particular snowflake) the outcome of accidents. The accidental features could be imprinted during the cooling that follows the big bang — rather as a piece of red-hot iron becomes magnetised when it cools down, but with an alignment that may depend on chance factors. It may turn out (though this would be a disappointment to many physicists if it did) that the key numbers describing our universe, and perhaps some of the so-called constants of laboratory physics as well, are mere "environmental accidents", rather than being uniquely fixed throughout the multiverse by some final theory. This is relevant to some now-familiar arguments (explored further in my book Our Cosmic Habitat) about the surprisingly fine-tuned nature of our universe.

Fine Tuning — A Motivation For Suspecting That Our "Universe" Is One Of Many.

The nature of our universe depended crucially on a recipe encoded in the big bang, and this recipe seems to have been rather special. A degree of fine tuning — in the expansion speed, the material content of the universe, and the strengths of the basic forces — seems to have been a prerequisite for the emergence of the hospitable cosmic habitat in which we live. Here are some prerequisites for a universe containing organic life of the kind we find on Earth:

First of all, it must be very large compared to individual particles, and very long-lived compared with basic atomic processes. Indeed this is surely a requirement for any hypothetical universe that a science fiction writer could plausibly find interesting. If atoms are the basic building blocks, then clearly nothing elaborate could be constructed unless there were huge numbers of them. Nothing much could happen in a universe that was was too short-lived: an expanse of time, as well as space, is needed for evolutionary processes. Even a universe as large and long-lived as ours, could be very boring: it could contain just black holes, or inert dark matter, and no atoms at all; it could even be completely uniform and featureless. Moreover, unless the physical constants lie in a rather narrow range, there would not be the variety of atoms required for complex chemistry.

If our existence depends on a seemingly special cosmic recipe, how should we react to the apparent fine tuning? There seem three lines to take: we can dismiss it as happenstance; we can acclaim it as the workings of providence; or (my preference) we can conjecture that our universe is a specially favoured domain in a still vaster multiverse. Some seemingly "fine tuned" features of our universe could then only be explained by "anthropic" arguments, which are analogous to what any observer or experimenter does when they allow for selection effects in their measurements: if there are many universes, most of which are not habitable, we should not be surprised to find ourselves in one of the habitable ones.

Testing Specific Multiverse Theories Here And Now

We may one day have a convincing theory that tells us whether a multiverse exists, and whether some of the so called laws of nature are just parochial by-laws in our cosmic patch. But while we're waiting for that theory — and it could be a long wait — the "ready made clothes shop" analogy can already be checked. It could even be refuted: this would happen if our universe turned out to be even more specially tuned than our presence requires. Let me give two quite separate examples of how this style of reasoning can be used to refute specific hypotheses.

(i) Ludwig Boltzmann argued that our entire universe was an immensely rare "fluctuation" within an infinite and eternal time-symmetric domain. There are now many arguments against this hypothesis, but even when it was proposed one could already have noted that fluctuations in large volumes are far more improbable than in smaller volumes.

So, it would be overwhelmingly more likely, if Boltzmann were right, that we would be in the smallest fluctuation compatible with our existence (Indeed, the most probable fluctuation would be a disembodied brain that merely simulated the sensations of the external world.) Whatever our initial assessment of Boltzmann's theory, its probability would plummet if we came to accept the extravagant scale of the cosmos.

(ii) Even if we knew nothing about how stars and planets formed, we would not be surprised to find that our Earth's orbit wasn't highly eccentric: if it had been, water would boil when the Earth was at perihelion and freeze at aphelion — a harsh environment unconducive to our emergence. However, a modest orbital eccentricity (certainly up to 0.1) is plainly not incompatible with life. If it had turned out that the earth moved in a near-perfect circle (with eccentricity, say, less than 0.00001) , this would be a strong argument against a theory that postulated anthropic selection from orbits whose eccentricities had a "Bayesian prior" that was uniform in the range from zero to one.

We could apply this style of reasoning to the important numbers of physics (for instance, the cosmological constant lambda) to test whether our universe is typical of the subset that that could harbour complex life. Lambda has to be below a threshold to allow protogalaxies to pull themselves together by gravitational forces before gravity is overwhelmed by cosmical repulsion (which happens earlier if lambda is large). An unduly fierce cosmic repulsion would prevent galaxies from forming.

Suppose, for instance, that (contrary to current indications) lambda was thousands of times smaller than it needed to be merely to ensure that galaxy formation wasn't prevented. This would raise suspicions that it was indeed zero for some fundamental reason. (Or that it had a discrete set of possible values, and all the others were well about the threshold).

The methodology requires us to decide what values of a particular physical parameter are compatible with our emergence. It also requires a specific theory that gives the relative Bayesian priors for any particular value. For instance, in the case of lambda, are all values equally probable? Are low values favoured by the physics? Or is there a finite number of discrete possible values, depending on how the extra dimensions "roll up"? With this information, one can then ask if our actual universe is "typical" of the subset in which we could have emerged. If it is a grossly atypical member even of this subset (not merely of the entire multiverse) then we would need to abandon our hypothesis. By applying similar arguments to the other numbers, we could check whether our universe is typical of the subset that that could harbour complex life. If so, the multiverse concept would be corroborated.

As another example of how "multiverse" theories can be tested, consider Smolin's conjecture that new universes are spawned within black holes, and that the physical laws in the daughter universe retain a memory of the laws in the parent universe: in other words there is a kind of heredity. Smolin's concept is not yet bolstered by any detailed theory of how any physical information (or even an arrow of time) could be transmitted from one universe to another. It has, however, the virtue of making a prediction about our universe that can be checked. If Smolin were right, universes that produce many black holes would have a reproductive advantage, which would be passed on to the next generation. Our universe, if an outcome of this process, should therefore be near-optimum in its propensity to make black holes, in the sense that any slight tweaking of the laws and constants would render black hole formation less likely. (I personally think Smolin's prediction is unlikely be borne out, but he deserves our thanks for presenting an example that illustrates how a multiverse theory can in principle be vulnerable to disproof.) These examples show that some claims about other universes may be refutable, as any good hypothesis in science should be. We cannot confidently assert that there were many big bangs — we just don't know enough about the ultra-early phases of our own universe. Nor do we know whether the underlying laws are "permissive": settling this issue is a challenge to 21st century physicists. But if they are, then so-called anthropic explanations would become legitimate — indeed they'd be the only type of explanation we'll ever have for some important features of our universe.

A Keplerian Argument

The multiverse concept might seem arcane, even by cosmological standards, but it affects how we weigh the observational evidence in some current debates. Our universe doesn't seem to be quite as simple as it might have been. About 5 percent of its mass is in ordinary atoms; about 25 percent is in dark matter (probably a population of particles that survived from the very early universe contains atoms, and dark matter; and the remaining 70 percent is latent in empty space itself.

Some theorists have a strong prior preference for the simplest universe and are upset by these developments. It now looks as thought a craving for such simplicity will be disappointed. Perhaps we can draw a parallel with debates that occurred 400 years ago. Kepler discovered that planets moved in ellipses, not circles. Galileo was upset by this. In his "Dialogues concerning the two chief systems of the world" he wrote "For the maintenance of perfect order among the parts of the Universe, it is necessary to say that movable bodies are movable only circularly".

To Galileo, circles seemed more beautiful; and they were simpler — they are specified just by one number, the radius, whereas an ellipse needs an extra number to define its shape (the "eccentricic"). Newton later showed, however, that all elliptical orbits could be understood by a single unified theory of gravity. Had Galileo still been alive when Principia was published, Newton's insight would surely have joyfully reconciled him to ellipses.

The parallel is obvious. A universe with at least three very different ingredients low may seem ugly and complicated. But maybe this is our limited vision. Our Earth traces out just one ellipse out of an infinity of possibilities, its orbit being constrained only by the requirement that it allows an environment conducive for evolution (not getting too close to the Sun, nor too far away). Likewise, our universe may be just one of an ensemble of all possible universes, constrained only by the requirement that it allows our emergence. So I'm inclined to go easy with Occam's razor: a bias in favour of "simple" cosmologies may be as short-sighted as was Galileo's infatuation with circles.

What we've traditionally called "the universe" may be the outcome of one big bang among many, just as our Solar System is merely one of many planetary systems in the Galaxy. Just as the pattern of ice crystals on a freezing pond is an accident of history, rather than being a fundamental property of water, so some of the seeming constants of nature may be arbitrary details rather than being uniquely defined by the underlying theory. The quest for exact formulas for what we normally call the constants of nature may consequently be as vain and misguided as was Kepler's quest for the exact numerology of planetary orbits. And other universes will become part of scientific discourse, just as "other worlds" have been for centuries. We may one day have a convincing theory that accounts for the very beginning of our universe, tells us whether a multiverse exists, and (if so) whether some so called laws of nature are just parochial by-laws in our cosmic patch. may be vastly larger than the domain we can now (or, indeed, can ever) observe. Most physicists hope to discover a fundamental theory that will offer unique formulae for all the constants of nature. But perhaps what we've traditionally called our universe is just an atom in an ensemble — a multiverse punctuated by repeated big bangs, where the underlying physical laws permit diversity among the individual universes.

Even though some physicists still foam at the mouth at the prospects of be being "reduced" to these so-called anthropic explanations, such explanations may turn out to be the best we can ever discover for some features of our universe (just as they are the best explanations we can offer for the shape and size of Earth's orbit). Cosmology will have become more like the science of evolutionary biology. Nonetheless (and here physicists should gladly concede to the philosophers), any understanding of why anything exists — why there is a universe (or multiverse) rather than nothing — remains in the realm of metaphysics.

Sir Martin Rees, a cosmologist, is Royal Society Professor at Kings College, Cambridge. He directs a research program at Cambridge's Institute of Astronomy. His most recent book is Our Cosmic Habitat.

"How will people think about the soul?"

Cognitive scientists believe that emotions, memories, and consciousness are the result of physical processes. But almost nobody else does. Common sense tells us that our mental life is the product of an immaterial soul, one that can survive the destruction of the body and brain. The physical basis of thought is, as Francis Crick put it, "an astonishing hypothesis", one that few take seriously.

You might think that this will soon change. After all, people once thought the earth is flat and that mental illness is caused by demonic possession. But the belief in the immaterial soul is different. It is rooted in our experience — our gut feeling, after all, is not that we are bodies; it is that we occupy them. Even young children are dualists — they appreciate and enjoy tales in which a person leaves his body and goes to faraway lands, or when the frog turns into a prince. And when they come to think about death, they readily accept that the soul lives on, drifting into another body or ascending to another world.

When the public hears about research into the neural basis of thought, they learn about specific findings: this part of the brain is involved in risk taking, that part is active when someone think about music, and so on. But the bigger picture is not yet generally appreciated, and it is an interesting question how people will react when it is. (We are seeing the first signs now, much of it in the recent work of novelists such Jonathan Franzen, David Lodge, and Ian McEwan). It might be that non-specialists will learn to live with the fact that their gut intuitions are mistaken, just as non-physicists accept that apparently solid objects are composed of tiny moving particles. But this may be optimistic. The notion that our souls are flesh is profoundly troubling, in large part because of what it means for the idea of life after death. The same sorts of controversies that raged over the study and teaching of evolution in the 20th century might well spill over to the cognitive sciences in the years to follow.

Paul Bloom is Professor of Psychology at Yale and author of How Children Learn the Meanings of Words (Learning, Development, and Conceptual Change).

"How can we understand the fact that such complex and precise mathematical relations inhere in nature?"

Of course this is one of the oldest philosophical questions in science but still one of the most mysterious. For most of Western history the cannonical answer has been some version of Platonism, some variation on the esentially Pythagorean idea that the matherial universe has been formed according to a set of transcendent and a priori mathematical relations or laws. These relations/laws Pythagaoras himself called the divine armonia of the cosmos, and have often been referred to since as the "cosmic harmonies" or the "music of the spheres". For Pythagoras numbers were actually gods, and the quest for mathematical relations in nature was a quest for the divine archetypes by which he believed that matter had literally been in-formed. Throughout the age of science, and even today, most physicists seem to be Platonists. Many are even Pythagoreans, implicitly (if not always with much concious reflection) making an association between the mathematical laws of nature and a transcendent being. The common association today of a "theory of everything" with "the mind of God" is simply the latest efflourescence of a two and a half millenia-old tradition which has always viewed physics as a quasi-religious activity.

Can we get beyond Platonism in our understanding of nature's undeniable propensity to realize extraordinarily sophisticated mathematical relations? Although I began my own life in science as a Platonist I have come to believe that this philosophical position is insupportable. It is not a rationally justifiable position at all, but simply a faith. Which is fine if one is prepaared to admit as much, something few physicists seem willing to do. To believe in an a priori set of laws (perhaps even a single law) by which physical matter had to be informed seems to me just a disguised version of deism — an outgrowth of Judeo-Christianity wrapped up in scientific language. I believe we should do better than this, that we should articulate (and need to articulate) a post-Platonist understanding of the so-called "laws of nature." It is a far from easy task, but not an impossible one. Just as mathematican Brian Rotman has put forward a post-Platonist account of mathematics we need to achieve a similar move for physics and our mathematical description of the world itself.

Margaret Wertheim is a science writer and commentator and the author of The Pearly Gates of Cyberspace: A History of Space from Dante to the Internet.

"Where Are They?"

When Enrico Fermi asked his famous question (now known as the Fermi Paradox) more than fifty years ago — if there is advanced extraterrestrial life, intelligence, and technology, why don't we see unmistakable evidence of it? — it was the era of 60-megaton atmospheric bomb tests and broadcast television, with unlimited fusion power in plain sight.

Now, we don't even have underground testing, TV has gone cable, wireless is going spread-spectrum, technology has grown microscopic, our children encrypt text with PGP and swap audio via MP3, and Wolfman Jack no longer broadcasts across the New Mexico desert at 50,000 watts.

Fermi's question is still worth asking — and may not be the paradox we once thought.

George Dyson is a historian among futurists and the author of Darwin Among the Machines.

"What is the nature of learning?"

That question strikes me as being as infinitely perplexing and personal as, What's the meaning of life? But that's the beauty of its ambiguity, and the challenge I enjoy grasping at its slippery complexity.

Recent insights into the neural basis of memory have provided a couple of key pieces to the puzzle of learning. The neuropsychological research on "elaborative encoding," for example, has shown that the long-term retention of information involves a spontaneous, connection-making process that produces web-like associative linkages of evocative images, words, objects, events, ideas, sensory impressions and experiences.

Parallel insights have emerged from the exploratory work on learning that's being conducted in the field of education and business, which involves constructing multi-dimensional symbolic models. The symbolic modeling process enables people to give form to their thoughts, ideas, knowledge, and viewpoints. By making tangible the unconscious creative process by which we use our tacit and explicit knowledge, the symbolic models help reveal what we think, how we think and what we remember. They represent our thought processes in a deep and comprehensive way, showing the different ways we use our many intelligences, styles of learning, and creative inquiry. In effect, the models demonstrate how people create things to remember, and remember things by engaging in a form of physical thinking.

Underneath our layers of individuality lives a core of universal emotions that comprise a "global common language." This language of feelings and sensory impressions not only unites us as human beings, but also connects our creative process. It also enables us to generate ideas together, create new knowledge and transfer it, come to some deep shared understanding of ourselves or given subject, as well as communicate this understanding across the various cultural, social and educational barriers, that divide us. The studies on elaborative encoding provide some basic insights into how these symbolic models work as a kind of global common language, which people use to freely build on the things they already knew and have an emotional connection with.

In short: the symbolic models open up other pathways to understand-ing the brainwork behind learning, remembering and the process by which we selectively apply what we learn when we create.

As Dr. Barry Gordon of Johns Hopkins School of Medicine states, "What we think of as memories are ultimately patterns of connection among nerve cells." The Harvard psychologist Daniel Schachter arrived at a similar conclusion when examining the 'unconscious processes of implicit knowledge' and its relation to memory.

Clearly, when our brains are engaged by information that, literally and figuratively speaking, "connects with us" (in more ways than one), we not only remember it better, but tend to creatively act on it as well. Symbolic modeling makes this fact self-evident.

How can we improve the way we learn, and foster the learning process over a lifetime? How can we make the information we absorb daily more personally meaningful, purposeful and memorable?

The answers remain to be seen in our connection-making process. This private act of creation is becoming increasingly more public and apparent through functional MRI studies and other medical imaging techniques. Perhaps a more productive strategy for illuminating this connection-making process would be to combine these high-tech "windows" to the world of the mind with low-tech imaging tools, such as symbolic modeling. The combination of these tools would provide a more comprehensive picture of learning.

The ability to learn ­ or inability ­ seems to determine our happiness and well being, not to mention the success we experience from realizing our potential. Understanding the conditions that galvanize great, memorable learning experiences will move us closer to understanding the creative engine that powers our individual and collective growth: learning.

Todd Siler is the founder and director of Psi-Phi Communications and author of Think Like A Genius.

"Will humankind be able to use its growing self-knowledge to overcome the biologically programmed instincts that could otherwise destroy it?"

I am intrigued by the interplay between the following:

1) People always want a little bit more than they have.

2) The economic and political systems built on this instinct are conquering the world.

3) Yet there is no correlation between owning a little bit more and happiness. Instead, the long-term effect of everyone seeking to own a little bit more could be calamitous.

Historically, religious figures have appealed to people to overrule their greed with a concern for some higher good. In our supposed scientific age, these arguments have lost their force. Instead our public affairs are governed by the idea that people should just be free as much as possible to choose what they want.

But what if people are programmed to make choices that are not in their own best long-term interest? Suppose we discovered that what we instinctively thought would bring us happiness is an illusion created by our human-gene-built brains to induce human-gene-spreading behavior?

Today's evolutionary psychologists provide compelling arguments why this picture might be accurate. A species programmed to acquire stuff might well spread itself successfully across the globe. But evolution is blind. It has no plan regarding what might happen to that species when the globe has been conquered. And in the meantime our genes don't give a damn about our happiness. For them it's just another propagation technology... perhaps made doubly efficient by ensuring the carrot is yanked away each time it comes within reach. To achieve true happiness we may need to be a great deal wiser than the loudest demons in our head would suggest.

Will the new model of "Why We Are The Way We Are" finally convince us that our political and economic systems, and the assumptions on which they are based, are dangerously flawed. (The"problem isn't just the economists' assumption that "greed is good", or the politicians' assumption of politics that "growth is good'. We've all been brought up to believe: "natural is good". As if it weren't the most natural thing in the world for a planet to self-destruct.)

And how long will it take for the new ideas to have any impact? (What if it were to take 50 years? In an era of exponential growth, and accelerating technological change, can we afford even 10?)

More generally, can memes that have evolved in a single generation countermand the influence of genes that evolved over millions of years?

Chris Anderson is the incoming Chairman and Host of the TED Conference (Technology, Education, Design) held each February in Monterey, California and formerly a magazine publisher (Future Publishing).

"If the medium is indeed the message, does (or can) the message define the medium?"

(As a poet, I don't think I need to explicate the question.)

Gerd Stern is a poet, media artist and cheese maven and the author of an oral history From Beat Scene Poet to Psychedelic Multimedia Artist 1948-1978.

"What is the nature of fads, fashions, crazes, and financial manias? Do they share a structure that can in turn be found at the core of more substantial changes in a culture? In other words, is there an engine of change to be found in the simple fad that can explain and possibly predict or accelerate broader changes that we regard as less trivial than "mere" fads? And more importantly, can we quantify the workings of this engine if we decide that it exists?"

I have shelves of books and papers by smart people who have brushed up against the edge of this question but who have seldom attacked it head on. I'm drawn to the question, and have been obsessed with it for years, because I think it's one of the big ones. It touches on everything humans do.

Fashions and fads are everywhere; in things as diverse as food, furnishings, clothes, flowers, children's names, haircuts, body image, even disease symptoms and surgical operations. Apparently, even the way we see Nature and frame questions about it is affected to some extent by fashion; at least according to those who would like to throw cold water on somebody else's theory. (In the current discussion, Paul Davies says, "Of late, it is fashionable among leading physicists and cosmologists to suppose that alongside the physical world we see lies a stupendous array of alternative realitiesŠ")

But the ubiquity of fads has not led to deep understanding, even though there are serious uses to which a working knowledge of fads could be put. A million children each year die of dehydration, often where rehydration remedies are available. What if rehydration became fashionable among those children's mothers? Public health officials have many times tried to make various behaviors fashionable. In promoting the use of condoms in the Philippines or encouraging girls in Africa to remain in school, they've reached for popular songs and comic books to deliver the message, hoping to achieve some kind of liftoff. Success has been real, but too often temporary or sporadic. Would a richer understanding of fads have helped them create better ones?

In trying to understand these phenomena, writers have been engaged in a conversation that has spanned more than a hundred years. In 1895 Gustave LeBon's speculations on "The Crowd" contained some cockeyed notions, and some that are still in use today. Ludwik Fleck, writing on "The Evolution of a Scientific Fact" in the thirties, in part inspired Thomas Kuhn's writings on the structure of scientific revolutions in the sixties. Everrett Rogers's books on the "Diffusion of Innovations" led to hundreds of other books on the subject and made terms like early adopters and agents of change part of the language. For several decades positive social change has been attempted through a practice called Social Marketing, derived in part from advertising techniques. Diffusion and social marketing models have been used extensively in philanthropy, often with success. But to my knowledge these techniques have not yet led to a description of the fad that's detailed and testable.

Malcom Gladwell was stimulating in identifying elements of the fad in The Tipping Point but we are still left with a recipe that calls for a pinch of this and a bit, but not too much, of that.

Richard Dawkins made a dazzling frontal assault on the question when he introduced the idea of memes in The Selfish Gene. The few pages he devoted to the idea have inspired a number of books and articles in which the meme is considered to be a basic building block of social change, including fads. But as far as I can tell, the meme is still a fascinating idea that urges us toward experiments that are yet to be done.

Whether memes or some other formulation turns out to be the engine of fads, the process seems to go like this: a signal of some kind produces a response that in turn acts as a signal to the next person, with the human propensity for imitation possibly playing a role. This process of signal-response-signal might then spread with growing momentum, looking something like biological contagion. But other factors may also apply, as in Steve Strogatz's examination of how things sync up with one another. Or Duncan Watt's exploration of how networks of all kinds follow certain rules of efficiency. Or the way crowds panic in a football stadium or a riot. Or possibly even the studies on the way traffic flows, including the backward generated waves that cause mysterious jams. The patterns of propagation may turn out to be more interesting than anything else.

Fads and fashions have not been taken very seriously, I think, for at least three reasons. They seem short-lived, they're often silly and they seem like a break with normal, rational behavior. But as for being short-lived, the history of fads gives plenty of examples of fads that died out only to come back again and again, eventually becoming customary, including the use of coffee, tomatoes and hot chocolate. As for silliness, some fashions are not as silly as they seem. Fashions having to do with the length of one's hair seem trivial; yet political and religious movements have often relied on the prominence or absence of hair as a rallying symbol. And fads are far from aberrational. There are probably very few people alive who, at any one time, are not under the sway of a fad or fashion, if not dozens of them. And this is not necessarily a vacation from rational behavior on our part. On the contrary, it might be essential to the way we maximize the effectiveness of our choices. Two economists in California have developed a mathematical model suggesting that in following the lead of others we may be making use of other people's experience in a way that gives us a slightly higher chance of success in adopting a new product. The economists say this may explain a burst of popularity in a new product and possibly throw light on fads themselves.

But another reason fads may not have been examined in more detail, and this could be the killer, is that at least for the moment they just seem too complicated. Trying to figure out how to track and explain change is one of the oldest and toughest of questions. Explaining change among people in groups is perhaps complex beyond measure, and may turn out to be undoable. It may forever be an art and not a science. But still, the humble fad is too tantalizing to ignore.

We take it for granted and dismiss it, even while we're in the rapture of it. This commonplace thing that sits there like the purloined letter may or may not turn out to contain a valuable message for us, but it is staring us in the face.

Alan Alda, an actor, writer and director, is currently playing Richard Feynman in the stage play QED at Lincoln Center in New York.

"What comes after Science? When?"

Questions? I don't ask questions. I ask answers, and then make up the questions as I see fit. I assemble vast collections of answers and while finding the questions, I make connections in the process. These connections are new answers, and depending on my mood and how much time I have at my disposal, I set about finding questions for them as well. Often, if not usually, the question I find is: "Why on earth am I wasting my time on this (project du jour)?" Once in a great while, I'll find that something I've cooked up in my multi-media cauldron "fits" just right — an appropriate gesture at a propitious moment, and it arrives with no explanation, no equation, no excuse, no reason, nothing- it just sits there — absolutely correct to itself in every possible way.

The paradigm of Question/Answer doesn't really work in my world as I've never really found Life, The Universe, and Everything (LU&E) and most (but not all) of its constituent parts and systems to be fundamentally amenable to it. From my research, I've come to a general conclusion that LU&E and most of its parts are fundamentally not knowable, or even humanly understandable in any linguistic or mathematical sense, except when framed in a more narrow set of terms, like "metaphor" or "pretend" or "just so".

A dear friend of mine once noted: "Nobody knows and you can't find out" and I largely agree with him. However, I can also say that, like being in the presence of a bucket of bricks, this is all more an experiential thing, more like a synchronistic aesthetic moment and less like a diachronistic or ahistorically definitive mathematical proposition or linguistically intelligible conclusion. So, one can't "know" it, nor can one "find out", but one can come to a sensibility that is convincing at the time and creatively informs one's behaviour and choices.

Hence, the only justice in this life is poetic, and everything else is just some tweaky form of petty revenge or (more typically in this life of entertainment and cultural anaesthesiology) dodging bullets while one waits for the big storm to blow over.

It can be infuriating (to me and most everyone else, it seems) when my work or research comes such conclusions, but since when has there been some big carved-in-stone guarantee that it's supposed to make sense in the first place? Isn't a rational conclusion a bit presumptuous and arrogant? From what I can gather it seems that the complete object of study fundamentally doesn't and shouldn't make sense (as sense seems to be a tiny subset surrounded by a vast multitude of complex forms of "nonsense"), and see that not as a shortcoming on the part of the Universe, as much as it is an indication of the limitations of human reason and the short time we get to spend on this planet.

But all this is probably not what you wanted to hear, so here's a good question that's been bugging me for years and if anyone wants to submit an answer, let me know - I'm all ears...

Mister Warwick asks:

"What comes after Science? When?"

Henry Warwick is an artist, composer, and scientist.

"What is time, and what is the right language to describe change, in a closed system like the universe, which contains all of its observers?"

This is, I believe, the key question on which the quantum theory of gravity and our understanding of cosmology, depends. We have made tremendous progress in the last years towards each goal, and we come to the point where we need a new answer to this question to proceed further. The basic reason for this problem is that most notions of time, change and dynamics which physics, and science more generally, have used are background dependent. This means that they define time and change in terms of fixed points of reference which are outside the system under study and do not themselves change or evolve. These external points of reference include usually the observer and clocks used to measure time. They constitute a fixed background against which time and change are defined. Other aspects of nature usually assumed to be part of the background are the properties of space, such as its dimensionality and geometry.

General relativity taught us that time and space are parts of the dynamical system of the world, that do themselves change and evolve in time. Furthermore, in cosmology we are interested in the study of a system that by definition contains everything that exists, including all possible observers. However, in quantum theory, observers seem to play a special role, which only makes sense if they are outside the system. Thus, to discover the right quantum theory of gravity and cosmology we must find a new way to formulate quantum theory, as well as the notions of time and change, to apply to a system with no fixed background, which contains all its possible observers. Such a theory is called background independent.

The transition from background dependent theories to background independent ones is a basic theme of contemporary science. Related to it is the change from describing things in terms of absolute properties intrinsic to a given elementary particle, to describing things in terms of relational properties, which define and describe any part of the universe only through its relationships to the rest.

In loop quantum gravity we have succeeded in constructing a background independent quantum theory of space and time. But we have not yet understood completely how to put the observer inside the universe. String theory, while it solves some problems, has not helped here, as it is so far a purely background dependent theory. Indeed string theory is unable to describe closed universes with a positive cosmological constant, such as observations now favor.

Among the ideas which are now in play which address this issue are Julian Barbour's proposal that time does not exist, Fotini Markopoulou's proposal to replace the single quantum theory relevant for observing a system from the outside with a whole family of quantum theories, each a description of what an observer might see from a particular event in the history of the universe and 't Hooft's and Susskind's holographic principle. This last idea says that physics cannot describe precisely what is happening inside a region of space, instead we can only talk about information passing through the boundary of the region. I believe these are relevant, but none go far enough and that we need a radical reformulation of our ideas of time and change.

As the philosopher Peirce said over a century ago, it is fundamentally irrational to believe in laws of nature that are absolute and unchanging, and have themselves no origin or explanation. This is an even more pressing issue now, because we have strong evidence that the universe, or at least the part in which we live, came into existence just a few billion years ago. Were the laws of nature waiting around eternally for a universe to be created to which they could apply? To resolve this problem we need an evolutionary notion of law itself, where the laws themselves evolve as the universe does. This was the motivation for the cosmological natural selection idea that Martin Rees is so kind to mention. That is, as Peirce understood, the notions of evolution and self-organization must apply not just to living things in the universe, but the structure of the universe and the laws themselves.

Lee Smolin, a theoretical physicist, is a founding member and research physicist at the Perimeter Institute in Waterloo Canada author of Three Roads to Quantum Gravity.

"Why doesn't conservation click?"

Three decades ago I began my first career working on a British television series called "Survival". Unlike the current "Survivor" series (about the politics of rejection while camping out) these were natural history documentaries on a par with the best of National Geographic and Sir David Attenborough: early recordings of humpback whales, insights on elephant behavior, the diminishing habitats of mountain gorillas and orangutans, a sweeping essay on the wildebeest migration, and my favorite, an innovative look at the ancient baobab tree.

In 2001 the "Survival" series died. It was a year when conservation efforts lagged across the board, along with other failures to take the long view. Survival programs may have told people what they could no longer bear to hear (that the human species is soiling its own den) without demonstrating constructive solutions. For example, there are precious few incentives to develop alternate energy sources despite the profound vulnerabilities that our dependence on foreign energy revealed yet again. We have no "Vision Thing," despite the many clues. "It's global warming, dude," a 28 year-old auto mechanic told The New York Times as he fished in the Hudson River; "I don't care if the whole planet burns up in a hundred years. If I can get me a fish today, it's cool by me."

Happily this provides a continuum to the question I posed at this forum in 1998:

"If tragedy + time = comedy, what is the formula for equally therapeutic music? Do (Blues) musicians reach a third person perspective similar to that found in meditation, mind-altering drugs, and genius?"

What I was reaching for with that third person perspective was a selfless overview. What I've since found is that healing dances of Native Americans and some African peoples follow the saga of a hero or heroine, much the way you or I listen to Bob Dylan or Bonnie Raitt and identify with their lyrics.

While Carl Jung delved into the healing ritual archetype among many cultures, a new science called Biomusicology suggests even more ancient origins, tracing the inspiration for human music to natural sounds (the rhythm of waves lapping at the shore, rain and waterfalls, bird song, breathing, and our mother's heartbeat when we were floating in the womb.) Songs of birds certainly influenced classical music, and the call and response patterns of birds were imitated in congregations and cotton fields, with shouts, which led to the Delta blues.

The salubrious influence of music, including research by Oliver Sacks, is featured in a Discovery Channel program that I helped research. "The Power of Music" will be broadcast in 2002, as will Sir David Attenborough's new series on a similar theme, "Songs of the Earth." But will these programs inspire viewers to relinquish their SUVs for a hydrogen-powered car? How does one convince people to address global warming when most minds are focused on the economy or terrorism?

Part one of this answer must include "An Ounce of Prevention." Richard A. Clarke, former White House director of counterterrorism, explained our ill preparedness for September 11 this way: "Democracies don't prepare well for things that have never happened before." Another senior analyst said. "Unfortunately, it takes a dramatic event to focus the government's and public's attention." Finally, efforts to prevent hijackings have been responsive, rarely proactive.

As we devise our New Year's Resolutions, how many of us will wait for a scare (positive diagnosis) before we quit smoking, drinking or sitting on our duff? Year 2002 should be the time when conservationists not only demand action, but persuade people everywhere that the demise of wild places can and should be stopped, that some of our forces of habit (unneeded air conditioning, for example) will eventually affect our quality of life in ways of greater devastation. We need people to identify with the song lyrics of others, who may live in distant lands, and feel the brunt of global warming long before we do. But first we must learn to understand their language.

In The Unbearable Lightness of Being, Milan Kundera wrote, "True human goodness, in all its purity and freedom, can come to the fore only when its recipient has no power. Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude toward those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it." Survival indeed.

Delta Willis has searched for fossils alongside Meave and Richard Leakey, profiled physicists and paleontologists who draw inspiration from nature, and serves as chief contributor to the Fodor's Guide to Kenya & Tanzania.

Why is it only amongst adults in the Western world that has tradition been so insistently and constantly challenged by the raising of Edge questions?

Why do we ask Edge questions?

Why do we ask Edge questions that challenge the "anesthesiology" of accepted wisdom and so the traditional answers we are given as to who and what we are? In most societies, accepted wisdom is to be respected not questioned, and who and what we are have long been decided by custom, elders, social betters and the sacred word of God. Moreover, why is it that the asking of Edge questions has only thrived and been encouraged in Western societies (with the help of such individuals as Socrates and the contributors to this Edge project)?

Children it should be noted readily ask Edge-type questions. The problem is that they stop when they become adults except in the civilization (with a few ups and downs) that started in Classical Greece — Western civilization.

"Are all our beliefs in gods, a myth, a lie foolishly cherished, while blind hazard rules the world?" That perhaps is the first Edge question (Euripides, Hecabe, lines 490-491) — and importantly a question not raised safely in private but before a large audience. Indeed, Euripides raised it to gain public reward. Greek playwrights wrote plays for competitions that were judged by ten randomly selected members of the audience — and given Euripides wanted to win — he must have believed that the average Greek would be hearing this Edge question raised about the Gods.

The public exploring of Edge questions is rare outside Western societies. Instead, "what was finally persuasive was appeal to established authority", and that, "the authority of tradition came to have more convincing effect than even direct observation and personal experience" (Robert Oliver, Communication And Culture In Ancient India And China, 1971). And as the Japanese scholar Hajime Nakamura noted, the Chinese "insisted that the traditional sacred books are more authoritative than knowledge based upon sense and inference" (Ways Of Thinking Of Eastern Peoples, 1964). Job might seem to be asking the Edge question "Why do the just suffer and the wicked flourish?" But the story of Job is not about rewarding Edge questioning but faith in the wisdom of God: "Who is this that darkens my counsel with words without knowledge".

This Edge question might be criticized as Eurocentric. But it was Western intellectuals that first asked the Edge question about whether ones own culture might be privileged falsely over others and so invented the idea of ethnocentricity.

So my Edge question is this: why is it only amongst adults in the Western world that has tradition been so insistently and constantly challenged by the raising of Edge questions?

John R. Skoyles is a researcher in the evolution of human intelligence in the light of recent discoveries about the brain, who, while a first-year student at LSE, published a theory of the origins of Western Civilization in Nature.

Paul Davies Responds

Response to John McCarthy:

John McCarthy asks how animal behavior is encoded in DNA. May I sharpen the question? One of the most remarkable manifestations of inherited behavior is the way birds navigate accurately whilst migrating over vast distances. I understand that part of this skill lies with the bird's ability to use the positions of stars as beacons. Does this imply that some avian DNA contains a map of the sky? Could a scientist in principle sequence the DNA and reconstruct the constellations?

Response to Martin Rees's response to my question:

Sir Martin Rees has eloquently outlined the key issues concerning the status of multiverse theories. I should like to make a brief response followed by a suggestion for further research.

Sir Martin raises the question of whether what we consider to be fundamental laws of physics are in fact merely local bylaws applicable to the universe we perceive. Implicit in this assumption is the fact that there are laws of some sort anyway. By definition, a law is a property of nature that is independent of time. We still need to explain why universes come with such time-independent lawlike features, even if a vast and random variety of laws is on offer. One might try to counter this by invoking an extreme version of the anthropic theory in which there are no laws, just chaos. The apparent day-by-day lawfulness of the universe would then itself be anthropically selected: if a crucial regularity of nature suddenly failed, observers would die and cease to observe. But this theory seems to be rather easily falsified.

As Sir Martin points out, if a particular remarkable aspect of the laws is anthropically selected from a truly random set, then we would expect on statistical grounds the aspect concerned to be just sufficient to permit biological observers. Consider, then, the law of conservation of electric charge. At the atomic level, this law is implied by the assumed constancy of the fine-structure constant. (I shall sidestep recent claims that this number might vary over cosmological time scales.) Suppose there were no such fundamental law, and the unit of electric charge varied randomly from moment to moment? Would that be life-threatening? Not if the variations were small enough. The fine-structure constant affects atomic fine-structure, not gross structure, so that most chemical properties on which life as we know it depends are not very sensitive to the actual value of this number.

In fact, the fine-structure constant is known to be constant to better than one part in a hundred million. A related quantity, the anamolous magnetic moment of the electron, is known to be constant to even greater accuracy. Variations several orders of magnitude larger than this would not render the universe hostile to carbon-based life. So the constancy of electric charge at the atomic level is an example of a regularity of nature far in excess of what is demanded by anthropic considerations. Even a multiverse theory that treated this regularity as a bylaw would need to explain why such a bylaw exists.

I now turn to my meta-question of whether the multiverse might be no better than theism in modern scientific language. It is possible that this claim can be tested using a branch of mathematics known as algorithmic information theory, developed by Kolmogorov and Chaitin. This formalism offers a means to quantify Occam's Razor, by quantifying the complexity of explanations. (Occam's Razor suggests that, all else being equal, we should prefer the simplest explanation of the facts.)

On the question of how to explain certain fine-tuned bio-friendly aspects of the universe, the crude response "God made it that way" is infinitely complex (and therefore very unsatisfying), because God might have made one of an infinite number of alternative universes. Put differently, the selection set — the "shopping list" of universes available to an omnipotent Deity — contains an infinite amount of information, so the act of selection from this set involves discarding this infinite quantity of information. In the same way, the multiverse contains an infinite amount of information. In this case we observers are the selectors, but we still discard an infinite quantity of information by failing to observe the other universes. A proper mathematical parameterization of various multiverse theories and various theological models should enable this comparison to be made precise.

Even if the two modes of explanation — theistic and multiverse — turned out to be mathematically equivalent — one might still argue (as Sir Martin has done) for the superiority of the multiverse theory on the grounds that the other universes, whilst not directly observable, are nevertheless strongly implied by extrapolation from the structure of our physical theories. But a theist would readily counter that the existence of God, whilst not directly obervable, is nevertheless strongly implied by extrapolation from the nature of the world, human wisdom, mystical revelation, moral awareness, etc.

I argued in my book The Mind of God that most attempts at ultimate explanations run into this "tower of turtles" problem: one has to start somewhere in the chain of reasoning, with a certain unproved given, be it God, mathematics, a physical principle, revelation, or something else. That is because of an implied dualism common to scientific and theistic explanations alike. In science the dualism is between states of the world and abstract laws. In theism it is between creature (i.e. the physical universe) and Creator.

But is this too simplistic? Might the physical world and its explanation be ultimately indecomposable? Should we consider alternative modes of description than one based on linear reasoning from an unproved given, which after all amounts to invoking a magical levitating superturtle at the base of the tower? That is what I meant by the "Third Way" in my original question.

Could our lack of theoretical insight in some of the most basic questions in biology in general, and consciousness in particular, be related to us having missed a third aspect of reality, which upon discovery will be seen to always have been there, equally ordinary as space and time, but so far somehow overlooked in scientific descriptions?

Is the arena of physics, constructed out of space and time with matter/energy tightly interwoven with space and time, sufficient to fully describe all of our material world? The most fundamental debates in cognitive science take a firm "yes" for granted. The question of the nature of mind then leaves open only two options: either a form of reductionism, or a form of escapism. The latter option, a dualist belief in a separate immaterial mental realm has fallen out of favor, largely because of the astounding successes of natural science. The former, reductionism, is all that is left, whether it is presented in a crude form (denial of consciousness as real or important) or in a more fancy form (using terms like emergence, as if that would have any additional explanatory power).

The question I ask myself is whether there could not be another equally fundamental aspect to reality, on a par with space and time, and just as much part of the material world?

Imagine that some tribe had no clear concept of time. Thinking only in terms of space, they would have a neat way to locate everything in space, and they would scoff at superstitious notions that somehow there would be "something else", wholly other than space and the material objects contained therein. Of course they would see things change, but both during and after each change everything has its location, and the change would be interpreted as a series of purely spatial configurations.

Yet such a geometric view of the world is not very practical. In physics and in daily life we use time in an equally fundamental way as space. Even though everything is already "filled up" with space, similarly everything participates in time. Trying to explain that to the people of the no-time tribe may be difficult. They will see the attempt at introducing time as trying to sneak in a second type of space, perhaps a spooky, ethereal space, more refined in some way, imbued with different powers and possibilities, but still as a geometric something, since it is in these terms that they are trained to think. And they probably would see no need for such a parallel pseudo-space.

In contrast, we do not consider time to be in any way less "physical" than space. Neither time nor space can be measured as such, but only through what they make possible: distances, durations, motion. While space and time are in some sense abstractions, and not perceivable as such, they are enormously helpful concepts in ordering everything that is perceivable into a coherent picture. Perhaps our problems in coming up with a coherent picture of mental phenomena tells us that we need another abstraction, another condition of possibility for phenomena in this world, this very material world we have always lived in.

Could it be that we are like that tribe of geometers, and that we have so far overlooked a third aspect of reality, even though it may be staring us in the face? Greek mathematicians used time to make their mathematical drawings and construct their theories, yet they disregarded time as non essential in favor of a Platonic view of unchanging eternal truths. It took two thousand years until Newton and Leibniz invented infinitesimal calculus, which opened the door for time to finally enter mathematics, thus making mathematical physics possible.

To reframe my question: could our lack of theoretical insight in some of the most basic questions in biology in general, and consciousness in particular, be related to us having missed a third aspect of reality, which upon discovery will be seen to always have been there, equally ordinary as space and time, but so far somehow overlooked in scientific descriptions?

Although I don't know the answer, I suspect we will stumble upon it through a trigger that will come from engineering. Newton did not work in a vacuum. He built upon what Galileo, Descartes, Huygens and others had discovered before him, and many of those earlier investigations were triggered by concrete applications, in particular the construction of powerful canons calling for better ways to compute ballistic orbits. Another example is the invention of thermodynamics. It took almost two centuries for Newtonian mechanics to come to grips with time irreversibility. Of course, every physicist had seen how stirring sugar in a cup of tea is not reversible, but until thermodynamics and statistical mechanics came along, that aspect of reality had mostly been ignored. The engineering problems posed by the invention of steam engines were what forced a deeper thinking about time reversibility.

Perhaps current engineering challenges, from quantum computers to robotics to attempts to simulate large-scale neural interactions, will trigger a fresh way of looking at the arena of space and time, perchance finding that we have been overlooking an aspect of material reality that has been quietly with us all along.

Piet Hut, professor of astrophysics at the Institute for Advanced Study, in Princeton, is involved in the project of building GRAPEs, the world's fastest special-purpose computers.

"Is the universe really expanding? Or: Did Einstein get it exactly right?"

As I prepare to head for Cambridge (the Brits' one) for the conference to mark Stephen Hawking's 60th birthday, I know that the suggestion I am just about to make will strike the great and the good who are assembling for the event as my scientific suicide note. Suggesting time does not exist is not half as dangerous for one's reputation as questioning the expansion of the universe. That is currently believed as firmly as terrestrial immobility in the happy pre-Copernican days. Yet the idea that the universe in its totality is expanding is odd to say the least. Surely things like size are relative? With respect to what can one say the universe expands?

When I put this question to the truly great astrophysicists of our day like Martin Rees, the kind of answer I get is that what is actually happening is that the intergalactic separations are increasing compared with the atomic scales. That's relative, so everything is fine. Some theoreticians give a quite different answer and refer to the famous failed attempt of Hermann Weyl in 1917 to create a genuinely scale-invariant theory of gravity and unify it with electromagnetism at the same time. That theory, beautiful though it was, never made it out of its cot. Einstein destroyed it before it was even published with the simple remark that Weyl's theory would make the spectral lines emitted by atoms depend on their prior histories, in flagrant contradiction to observation. Polite in public, Einstein privately called Weyl's theory 'geistreicher Unfug' [inspired nonsense].

Ever since that time it seems to have been agreed that, for some inscrutable reason, the quantum mechanics of atoms and elementary particles puts an absolute scale into physics. Towards the end of his life, still smarting from Einstein's rap, Weyl wrote ruefully "the facts of atomism teach us that length is not relative but absolute" and went one to bury his own cherished ambition with the words "physics can never be reduced to geometry as Descartes had hoped".

I am not sure the Cartesian dream is dead even though the current observational evidence for expansion from a Big Bang is rather impressive. The argument from quantum mechanics, which leads to the identification of the famous Planck length as an absolute unit, seems to me inconclusive. It must be premature to attempt definitive statements in the present absence of a theory of quantum gravity or quantum cosmology. And the argument about the relativity of scale being reflected in the changing ratio of the atomic dimensions to the Hubble scale is vulnerable.

To argue this last point is the purpose of my contribution, which I shall do by a much simpler example, for which, however, the principle is just the same. Consider N point particles in Euclidean space. If N is greater than three, the standard Newtonian description of this system is based on 3N + 1 numbers. The 3N (=3xN) are used to locate the particles in space, and the extra 1 is the time. For an isolated dynamical system, such as we might reasonably conjecture the universe to be, three of the numbers are actually superfluous. This is because no meaning attaches to the three coordinates that specify the position of the centre of mass. This is a consequence of the relativity principle attributed to Galileo, although it was actually first cleanly formulated by Christiaan Huygens (and then, of course, brilliantly generalized by Einstein). The remaining 3N - 2 numbers constitute an oddly heterogeneous lot. One is the time, three describe orientation in space (but how can the complete universe have an orientation?), one describes the overall scale, and the remaining 3N - 7 describe the intrinsic shape of the system. The only numbers that are not suspect are the last: the shape variables.

Developing further ideas first put forward in 1902 in his Science and Hypothesis by the great French mathematician Poincare [ascii does not allow me to put the accent on his e], I have been advocating for a while a dynamics of pure shape. The idea is that the instantaneous intrinsic shape of the universe and the sense in which it is changing should be enough to specify a dynamical history of the universe. Let me spell this out for the celebrated 3 body problem of Newtonian celestial mechanics. In each instant, the instantaneous triangle that they form has a shape that can be specified by two angles, i.e., just two numbers. These numbers are coordinates on the space of possible shapes of the system. By the 'sense' in which the shape is changing I mean the direction of change of the shape in this two-dimensional shape space. That needs only one number to specify it. So a dynamics of pure shape, one that satisfies what I call the Poincare criterion, should need only three essential numbers to set up initial conditions. That's the only ideal that, in Poincare's words, would give the mind satisfaction. It's the ideal that inspired Weyl (though he attacked the problem rather differently).

Now how does Newtonian dynamics fare in the light of the Poincare criterion? Oddly enough, despite centuries of dynamical studies, this question hardly seems to have been addressed by anyone. However, during the last year, working with some N-body specialists, I have established that Newtonian mechanics falls short of the ideal of a dynamics of pure shape by no fewer than five numbers. Seen from the rational perspective of shape, Newtonian dynamics is very complicated. This is why the study of the Moon (which forms part of the archetypal Earth-Moon-Sun three-body problem) gave Newton headaches. Among the five trouble makers (which I won't list in full or discuss here), the most obstreperous is the one that determines the scale or size. The same five trouble makers are present for all systems of N point particles for N equal to or greater than 3. Incidentally, the reason why 3-body dynamics is so utterly different from 2-body dynamics is that shape only enters the picture when N = 3. Most theoretical physicists get their intuition for dynamics from the study of Newtonian 2-body dynamics (the Kepler problem). It's a poor guide to the real world.

The point of adding up the number of the variables that count in the initial value problem is this. The Newtonian three-body problem can be expressed perfectly well in terms of ratios. One can consider how the ratios of the individual sides to the perimeter of the triangle change during the evolution. This is analogous to following the evolution of the ratio of the atomic-radii to the Hubble radius in cosmology. To see if scale truly plays no role, one must go further. One must ask: do the observable ratios change in the simplest way possible as dictated by a dynamics of pure shape, or is the evolution more complicated? That is the acid test. If it is failed, absolute scale is playing its pernicious role. The Poincare criterion is an infallible test of purity.

Both Newtonian dynamics and Einstein's general relativity fail it. The fault is not in quantum mechanics but in the most basic structure of both theories. Scale counts. In fact, seen from this dynamical perspective Einstein's theory is truly odd. As James York, one of John Wheeler's students in Princeton, showed 30 years ago (in a beautiful piece of work that I regard as the highest point achieved to date in dynamical studies), the most illuminating way to characterize Einstein's theory is that it describes the mutual interaction of infinitely many degrees of freedom representing the pure shape of the universe with one single solitary extra variable that describes the instantaneous size of the universe (i.e., its 3-dimensional volume in the case of a closed universe). From Poincare's perspective, this extra variable, to put frankly, stinks, but the whole of modern cosmology hangs on it: it is used to explain the Hubble red shift.

There, I have stuck my neck out in good Popperian fashion. Current observations suggest I will have my head chopped off and Einstein will be vindicated. Certainly all the part of his theory to do with pure shape is philosophically highly pleasing and is supported by wonderful data. But even if true dynamical expansion is the correct explanation of the Hubble red shift, why did nature do something so unaesthetic? As I hope to show very shortly on the Los Alamos bulletin board, dynamics of pure shape can mimic a true Hubble expansion. The fact is that Einstein's theory allows red shifts of two kinds: one is due to stretching (expansion) of space, while the other is the famous gravitational red shift that makes clocks on the Earth run at a now observable amount slower than clocks in satellites. It is possible to eliminate scale from Einstein's theory, as Niall O'Murchadha and I have shown. This kills the stretching red shift but leaves the other intact. It is just possible that this could explain the Hubble red shift.

Let me conclude this possibly premature (but I feel justified, since all dogmas need to be challenged) contribution by pointing out that according to the standard Big-Bang scenario two things have been happening simultaneously since something lit the fuse: the universe has been expanding from an extraordinarily uniform and isotropic compressed state and it has simultaneously been getting more and more clumpy. Inflationists claim to have explained why we observe such a uniform Big Bang, but sceptics (which include me) have the uncomfortable feeling that an observational cosmic coincidence is merely being described, rather than explained, by theoretical fine tuning of an adjustable parameter. In a self-respecting universe that dismisses size as opposed to shape as a fiction, sharper predictions must be possible. In a dynamics of pure shape, the only thing that can happen is change of shape. That must explain the Hubble red shift. Merely by observing the rate at which matter and the universe in general becomes more clumpy, above all the rate of formation of gravitationally collapsed objects, astronomers ought to be able to predict the value of the Hubble constant.

So my challenge to the theoreticians is this: Are you absolutely sure Einstein got it exactly right? Prove me wrong in my hunch that the universe obeys a dynamics of pure shape subtly different from Einstein's theory. If size does count, why should nature do something so puzzling to the rational mind?

Julian Barbour is an independent theoretical physicist and author of The End of Time.

"When will we emerge from the quantum tunnel of obscurity?"

Can contradictory things happen at the same time? Does the universe continue about its business when we're not looking at it? These questions have been raised in the context of quantum mechanics ever since the theory was formulated in the 1920s. While most physicists dismissed these issues as "just philosophical", a small minority (inspired by the examples of Louis de Broglie, Albert Einstein and Erwin Schroedinger) continued to question the meaning of the most successful theory of science, and often suffered marginalisation and even ridicule.

It is one thing to apply quantum mechanics to calculate atomic energy levels or the rate at which atoms emit light. But as soon as one asks what is actually happening during an atomic transition, quantum mechanics gives no clear answer. The Copenhagen interpretation, forged by Niels Bohr and Werner Heisenberg, emphasises the subjective experience of "observers" and avoids any description of an objective reality; it talks about the chances of different outcomes occuring in a measurement, but does not say what causes a particular outcome to occur. For decades, students have been taught to avoid asking probing questions. An attitude of "shut-up-and-calculate" has dominated the field. The result is widespread confusion, and a strange unwillingness to ask clear and direct questions. As the late cosmologist Dennis Sciama once put it, whenever the subject of the interpretation of quantum mechanics comes up "the standard of discussion drops to zero".

The publication of John Bell's book Speakable and Unspeakable in Quantum Mechanics in 1987 provided a point of reference for a change in attitude that gained real momentum in the 1990s.

Bell spearheaded a movement to purge physics of some inherently vague notions inherited from the founding fathers of quantum mechanics. For instance the "measurement apparatus" was treated by Bohr and Heisenberg as something fundamentally distinct from the "system being measured": the latter was subject to the laws of quantum mechanics whereas the former was not. But if everything — including our equipment — is made of atoms, how can such a distinction be anything more than an approximation? In reality everything — "system", "apparatus", even human "observers" — should obey the same laws of physics. The clarity of Bell's writings forced many people to confront the uncomfortable fact that quantum mechanics as usually formulated had a problem explaining why we see definite events taking place.

Bell advertised what he saw as two promising avenues to resolve the quantum paradoxes: the theory must be supplemented either with a new random process that selects outcomes (the "dynamical reduction of the state vector") or with extra "hidden variables" whose unknown values select outcomes. Theories of both types have been constructed. Indeed, a correct hidden — variables theory was written down by Louis de Broglie as long ago as 1927, and was shown by David Bohm in 1952 to account completely for quantum phenomena. The de Broglie — Bohm theory gave an objective account of quantum physics; yet, until about 10 years ago, most physicists had not heard of it. Today, many have heard of it, but still very few understand it or work on it. And it is still not taught to students (even though in my experience many students would love to know more about this theory).

One wonders where things will go from here. On the one hand, in the last five years the subject of the interpretation of quantum mechanics has suddenly become more respectable thanks to the rising technology of quantum information and computation, which has shown that something of practical use — novel forms of communication and computation — can emerge from thoughts about the meaning of quantum mechanics. But on the other hand, there is a danger that the problem of the interpretation of quantum mechanics will be pushed aside in the rush to develop "real" technological applications of the peculiarities of quantum phenomena.

The rise of quantum information theory has also generated a widespread feeling that "information" is somehow the basic building block of the universe. But information about what? About information itself? As noted by P.W. Anderson in a recent Edge comment on Seth Lloyd, not only does it seem unjustified to claim that "information" is the basic stuff of the universe: worse, an unfortunate tendency has developed in some quarters to regard the theory of information as the only really fundamental area of reseach. Personally, I find quantum information theory very interesting, and it has without doubt enriched our understanding of the quantum world: but I fear that in the long run its most enthusiastic practitioners may lead us back to the vague subjectivist thinking from which we were only just emerging.

Antony Valentini is a theoretical physicist at Imperial College in London.

"How does being able to learn about a changing world endow our minds with expectations, imagination, creativity, and the ability to perceive illusions?"

When you open your eyes in the morning, you usually see what you expect to see. Often it will be your bedroom, with things where you left them before you went to sleep. What if you opened your eyes and found yourself in a steaming tropical jungle? or a dark cold dungeon? What a shock that would be! Why do we have expectations about what is about to happen to us? Why do we get surprised when something unexpected happens to us? More generally, why are we Intentional Beings who are always projecting our expectations into the future? How does having such expectations help us to fantasize and plan events that have not yet occurred? How do they help us to pay attention to events that are really important to us, and spare us from being overwhelmed by the blooming buzzing confusion of daily life? Without this ability, all creative thought would be impossible, and we could not imagine different possible futures for ourselves, or our hopes and fears for them. What is the difference between having a fantasy and experiencing what is really there? What is the difference between illusion and reality? What goes wrong when we lose control over our fantasies and hallucinate objects and events that are not really there? Given that vivid hallucinations are possible, especially in mental disorders like schizophrenia, how can we ever be sure that an experience is really happening and is not just a particularly vivid hallucination? If there a fundamental difference between reality, fantasy, and illusion, then what is it?

Recent models of how the brain controls behavior have begun to clarify how the mechanisms that enable us to learn quickly about a changing world throughout life also embody properties of expectation, intention, attention, illusion, fantasy, hallucination, and even consciousness. I never thought that during my own life such models would develop to the point that the dynamics of identified nerve cells in known anatomies could be quantitatively simulated, along with the behaviors that they control. During the last five years, ever-more precise models of such brain processes have been discovered, including detailed answers to why the cerebral cortex, which is the seat of all our higher intelligence, is organized into layers of cells that interact with each other in characteristic ways.

Although an enormous amount of work still remains to be done before such insights are fully developed, tested, and accepted, the outlines already seem clear of an emerging theory of biological intelligence, and with it, the scaffold for a more humane form of artificial intelligence. Getting a better understanding of how our minds learn about a changing world, and of how to embody their best features in more intelligent technologies, should ultimately have a transforming effect on many aspects of human civilization.

Stephen Grossberg is a Professor of Cognitive and Neural Systems, Mathematics, Psychology, and Engineering at Boston University.

"How will computation and communication change our everyday lives, again?"

The actual day to day things that we do have been changed drastically for many people in the world over the last twenty years by the arrival of personal computers. We spend hours each day in front of a screen, typing. This was not the norm twenty years ago (although a few of us did it even then), and no one had access to the vast stores of information that are available to us on our laps now. We no longer ask for reprints or go to the library, but instead download pdf versions of papers that interest us. We no longer need to go to reference works but instead retrieve them directly on our PCs. The number of people that we correspond with has increased dramatically — granted, the medium has changed too. And chatting on the phone to people on the other side of the world is no longer expensive or an event — it is just as common and cheap as calling someone a hundred miles away. Our interaction with media is changing too — it is becoming more and more pull rather than push, even for TV and radio entertainment — we choose when and where we want to receive it, and how we will store it.

Surprisingly, neither the book, nor the movie, nor the documentary are dead. There are more of them, in fact, although the method of delivery is slowly changing. We have increased our number of options rather than supplanted the old ones.

Moore's law and the increase of telecommunications infrastructure are both continuing. What new options should we expect, and how will they change the way we work? What will be the next "web", as unimagined by most educated people today as our current one was in 1988? And what will be the impact of the new methods of delivery we can expect to be developed in the next 20 years?

Already tens of thousands of people have cochlear implants with direct electronic to neural connections to restore their hearing. Multiple groups are working on retinal implants, either into the eyeball, or interfacing to V1 at the back of the head; again to replace lost capabilities such as those resulting from macular degeneration. A few quadraplegics have direct neural connections to computer interfaces so that they can control a mouse and even type. As progress is made with these silicon/neural interfaces, pushed along by clinical pressures to cure those who are impaired, we can expect more and more "plastic surgery" applications. A direct neural typing interface first perhaps, and later data going the other way directly from the network into our brains. There are considerable challenges to be met in understanding neural "coding" to do this, but the clinical imperative is pushing this work along.

How will we all be in the world then, 20 years from now say, when we all have direct wireless connections to the Internet of that time with information services as yet unimaginable? How will our grandchildren's interaction with information change the way they work and think, in the same way that instant messaging and vast numbers of web pages have changed the way our children in elementary and high school operate today?

Rodney Brooks is Director of the MIT Artificial Intelligence Laboratory, and Fujitsu Professor of Computer Science. He is also Chairman and Chief Technical Officer of IS Robotics,

"Would an extra-terrestrial civilization develop the same mathematics as ours? If not, how could theirs possibly be different?"

In writing my next book, about maths, I have been led to ponder this question by the fact that there are philosophers, and a few mathematicians, who believe that it is conceivable that there could be intelligences with a fully developed mathematics that does not, for example, recognize the integers or the primes, let alone Fermat's Last Theorem or the Riemann Hypothesis. And yet, whole numbers seem to us such a basic property of "things", that unless there were intelligences that were not embodied in any way (and/or couldn't "see" the discrete stars, for example) they would be bound to come across number and all that follows. But then, I suppose you could imagine intelligent beings which consisted, say, of density differences in a gas but lacked boundaries separating one from another. In any case, if such creatures do exist, it rather pours cold water on the use by SETI of maths (e.g. prime x prime pictorial grids) to communicate with them

Karl Sabbagh is a writer and television producer and author of A Rum Affair: A True Story of Botanical Fraud.

"Why do we fear the wrong things?"

A mountain of research shows that our fears modestly correlate with reality. With images of September 11th lingering in their mind's eye, many people dread flying to Florida for Spring break, but will instead drive there with confidence — though, mile per mile, driving during the last half of the 1990s was 37 times more dangerous than flying.

Will yesterday's safety statistics predict the future? Even if not, terrorists could have taken down 50 more planes with 60 passengers each and — if we'd kept flying — we'd still have been ended last year safer on commercial flights than on the road. Flying may be scary, but driving the same distance should be many times scarier.

Our perilous intuitions about risks lead us to spend in ways that value some lives hundreds of times more than other lives. We'll now spend tens of billions to calm our fears about flying, while subsidizing tobacco, which claims more than 400,000 lives a year.

It's perfectly normal to fear purposeful violence from those who hate us. But with our emotions now calming a bit, perhaps it's time to check our fears against facts. To be prudent is to be mindful of the realities of how humans suffer and die.

(To see my question developed — and answered — please click here).

David G. Myers is a social psychologist David G. Myers at Hope College (Michigan) and author of The Pursuit of Happiness.

"Are the laws of nature a form of computer code that needs and uses error correction?"

John D. Barrow is Research Professor of Mathematical Sciences, University of Cambridge and author of Between Inner Space and Outer Space.

"Can we ever escape our past, or are we doomed to a future of biobabble?"

In mid-November 1999, New Yorker writer Rebecca Mead published a commentary on the candidacy of Al Gore, and in it she gave us a new word. In the old days, candidates were advised in a pseudo-Freudian frame. Clinton, in pre-Monica times, was told to emphasize his role as "strong, assertive, and a good father." Now, however, this psychobabble has been eclipsed by what she called biobabble and Mead recommended that Gore's advice might best be based on evolutionary psychology instead of Freud. In other words, it wasn't your parents who screwed you up, it was the ancient environment. Mead cites Sarah Hrdy, a primatologist, as suggesting that the ideal presidential leader would be a grandma whose grandchildren were taken away and scattered across the country in secret locations. Then the president could be expected to act on the behalf of the general good, to maximize her reproductive fitness. No wonder Gore wasn't appointed.

This is déjà vu all over again, and after the last century of biopolicy in action, can we still afford to be here? Somehow we can't get away from a fixation on the link between biology and behavior. A causal relationship was long championed by the Mendelian Darwinians of the Western World, as breeding and sterilization programs to get rid of the genes for mental deficiencies became programs to get rid of the genes for all sorts of undesirable social behaviors, and then programs to get rid of the undesirable races with the imagined objectionable social behaviors. Science finally stepped back from the abyss of human tragedy that inevitably ensued, and one result was to break this link by questioning whether human races are valid biological entities. By now, generations of biological anthropologists have denied the biology of race. Arguing that human races are socially constructed categories and not biologically defined ones, biological anthropologists have been teaching that if we must make categories for people, "ethnic group" should replace "race" in describing them. 

The public has been listening. This is how the U.S. census came to combine categories that Americans base on skin color "African-American," delineated by "one drop of blood" with categories based on language "Latino." However ethnic groups revitalize the behavioral issue because ethnicity and behavior are indeed related, although not by biology, but by culture. This relationship is implicitly accepted as the grounds for the profiling we have heard so much about of late, but here is the rub. Profiling has accomplished more than just making it easier to predict behaviors, actually revitalizing the issue of biology and behavior by bringing back "race" as a substitution for "ethnic group." This might well have been an unintended consequence of using "race" and "ethnic group" interchangeably, because this usage forged a replacement link between human biology and human culture. Yet however it happened, we are back where we started, toying with the notion that human groups defined by their biology differ in their behavior.

And so, how do we get out of this? Can we? Or does the programming that comes shrink-wrapped with our state-of-the-art hardware continue to return our thinking to this point because of some past adaptive advantage it brought? It doesn't seem very advantageous right now.

Milford H. Wolpoff is Professor of Anthropology at the University of Michigan and author (with Rachel Caspari) of Race and Human Evolution: A Fatal Attraction.

"How different could life have been?"

Physicists, including several in this group, are fond of asking, "What if the universe had been different?" Are the fundamental constants just numbers we accept as given, but which could have been different? Or is there some deeper rationale, which we shall eventually discover, that renders them unfree to change? Is our universe the way universes have to be? Or is it one of a huge ensemble of universes? Given present company, I would not aspire to this question, fascinating as it is. Mine is its biological little brother. Is the life that we observe the way life has to be? Or could we imagine other kinds of life? Long the stock in trade of science fiction, I want to move it closer to science’s domain. Unfortunately the question is one for a chemist – which I am not. My hope is that chemists will listen, and work on it.

Life as we know it is far more uniform than superficially appears. The differences between an elephant and an amoeba are superficial. Biochemically speaking, we are all playing most of the same tricks. At this level, most of the variation in life is to be found among the bacteria. We large animals and plants have just specialised in a few of the tricks that bacterial R & D developed in the Precambrian.

But all living things, bacteria included, practise the same fundamental tricks. Using the universal DNA code, the one-dimensional sequence of DNA codons specifies the one-dimensional sequence of amino acids in proteins. This determines the proteins’ three-dimensional coiling, which specifies their enzymatic activity, and this, in turn specifies almost everything else. So, I’m not talking about whether living things on other planets will look like us, or will have television aerials sticking on their heads. It is easy to predict that heavy planets with high gravitational fields will breed elephants the size of flies (or flies built like elephants); light planets will grow elephant-sized flies with spindly legs. It is easy to predict that, where there is light, there will be eyes. This is not what I am talking about. I want the answer to a more fundamental question.

My question, which is for chemists, is this. Can you devise a fundamentally different, alternative biochemistry? Given that, as I firmly believe, life all over the universe must have evolved by the differential survival of something corresponding to genes – self-replicating codes whose nature influences their own long-term survival – do they have to be strung along polynucleotides? The genetic code itself almost certainly didn’t have to be the one we actually have – plenty of other codes would have done the job. Ours is a frozen accident which, once crystallised, could not change. But can you think of a completely different kind of molecule, not a polynucleotide at all, perhaps not even organic, which could do the coding? Does it have to be digital like the DNA/RNA code, or could some kind of analogue code be accurate and stable enough to mediate evolution? Does it even have to be a one-dimensional code? And is there any other class of molecules that could step into the shoes of proteins?

Biochemists, please stop focusing exclusively on the way life actually is. Think about how life might have been. Or how life could be on other worlds. Channel your creativity to devising a complete, alternative biochemistry, whose components are radically different from the ones we know, but are at the same time mutually compatible – participants in a wholly consistent system which your chemical calculations show could actually work.

Why should we want this? I wanted to ask the question, "Is there life on other worlds, and how similar is it to the life we know?" But there is no immediate prospect of our receiving direct answers to these questions, and I am pessimistic of our ever doing so. Life has probably arisen more than once, but on islands in space too widely scattered to make a meeting likely. Theoretical calculations may be our best hope, and are certainly our most immediate hope, of at least estimating the probabilities. There’s also the point, which hardly needs making on Edge, that to seek the unfamiliar is a good way to illuminate oneself.

Reply to Paul Davies’s response to John McCarthy

Paul Davies notes that some night-migrating birds navigate by the stars, and asks whether avian DNA contains a map of the sky. "Could a scientist in principle sequence the DNA and reconstruct the constellations?" Alas, no.

Stephen Emlen, of Cornell University, researched the matter in 1975. He placed Indigo Buntings in a circular cage in the centre of a planetarium, and measured their fluttering against different sides of the cage as an indicator of their preferred migratory direction. By manipulating the star patterns in the planetarium, blotting out patches of sky and so on, Emlen showed that the buntings did indeed use Polaris as their North, and they recognized it by the surrounding pattern of constellations.

So far so good. Now comes the interesting part. Is the pattern of stars built into the birds’ DNA, or is there some other, more general way to define the north (or south) pole of the heavens? Put it like that, and the point jumps out at you: the polar position in the sky can be defined as the centre of rotation! It is the hub that stays still, while the rest of the heavens turn. Did the birds use this as a rule for learning?

Emlen reared young buntings in the planetarium, giving them experience of different artificial ‘night skies’. Half of them, the controls, experienced a night sky that rotated about Polaris, as usual. The other half, the experimental birds, experienced a night sky in which the centre of rotation was Betelgeuse. The control birds ended up steering by Polaris, as usual. But the experimental birds, mirabile dictu, came to treat Betelgeuse as though it was due north. Clever, or what?

Richard Dawkins is an evolutionary biologist and the Charles Simonyi Professor For The Understanding Of Science at Oxford University. He is the author of Unweaving the Rainbow.

"How are moral assertions connected with the world of facts?"

Unlike many ancient philosophical problems, this one has, paradoxically, been made both more urgent and less tractable by the gradual triumph of scientific rationality. Indeed, the prevailing modern attitude towards it is a sort of dogmatic despair: ‘you can‘t get an ought from an is, therefore morality must be outside the domain of reason‘. Having fallen for that non-sequitur, one has only two options: either to embrace unreason, or to try living without ever making a moral judgement. In either case, one becomes a menace to oneself and everyone else.

On the tape of the bin Laden dinner party, a participant states his belief that during the September 11 attack, Americans were afraid that a coup d’état was under way. Worldwide, tens of millions of people believe that the Israeli secret service carried out the attack. These are factual misconceptions, yet they bear the imprint of moral wrongness just as clearly as a fossil bears the imprint of life. This illustrates an important strand in the fabric of reality: although factual and moral assertions are logically independent (one cannot deduce either from the other), factual and moral explanations are not. There is an explanatory link between ought and is, and this provides one of the ways in which reason can indeed address moral issues.

Jacob Bronowski pointed out that a commitment to discovering scientific truth entails a commitment to certain values, such as tolerance, integrity, and openness to ideas and to change. But there‘s more to it than that. Not only scientific discovery, but scientific understanding itself can depend on one’s moral stance. Just look at the difficulty that creationists have in understanding what the theory of evolution says. Look at the prevalence of conspiracy theories among the supporters of bad causes, and how such people are systematically blind to rational argument about the facts of the matter. And, conversely, look at Galileo, whose factual truth-seeking forced him to question the Church’s moral authority.

Why does this happen? We should not be surprised – at least, no more surprised than we are that, say, scientific and mathematical explanations are connected. The truth has structural unity as well as logical consistency, and I guess that no true explanation is entirely disconnected from any other. In particular, in order to understand the moral landscape in terms of a given set of values, one needs to understand some facts as being a certain way too, and vice versa. Moreover, I think it is a general principle that morally right values are connected in this way with true factual theories, and morally wrong values with false theories.

What sort of principle is this? Though it refers to morality, at root it is epistemological. It is about the structure of true explanations, and about the circumstances under which knowledge can or cannot grow. This, in turn, makes it ultimately a physical fact – but that is another story.

David Deutsch, a physicist, is a member of the Centre for Quantum Computation at the Clarendon Laboratory, Oxford University, and author of The Fabric of Reality.

"Why is beauty making a comeback now?"

My hypothesis is that the modernist/post-modernist idea that beauty is a social construct (with no deep bedrock in reality) is dead.

There are an increasing number of books coming out propounding the notion that beauty is real and crosses all sorts of cultural and historic lines. In their view, that which unites us as a species in the perception of beauty is way larger than what divides us.

My big question is whether, in a disjointed world in which the search for meaning is becoming ever more important, the existence of widely agreed upon ideas of beauty will increasingly become a quick and useful horseback way of determing whether or not *any* complex system, human or technological, is coherent.

This idea draws in part from pre-industrial age definitions of beauty that held that "Beauty is truth, truth beauty — that is all ye know on earth, and all ye need to know" (Keats, 1820), and most important, "The most general definition of beauty....multeity in unity" (Coleridge, 1814).

Interestingly enough, the idea that I view as increasingly dumb, "Beauty is in the eye of the beholder" Bartlett's dates only to 1878, which is about when the trouble started, in my view.

Joel Garreau is the cultural revolution correspondent of The Washington Post and author of Edge City.

"Do wormholes exist?"

Two startling ideas about wholly different classes of objects emerged from general relativity: black holes and wormholes. For over half a century black holes have grown in importance, with many convincing candidates in the sky and a vast range of theoretical support. "Einstein bridges" as they were first called, emerged in the 1930s, yet have not met with nearly the attention they deserve. We still don't know if any were made in the early universe. That seems by far the easiest way to find one‹inherit it from the Big Bang‹because to be stable they demand exotic matter. Matt Visser's Lorentzian Wormholes (1996) details the many types of wormholes allowed by theory. It's an impressive range, mostly unexplored theoretically.

If they do exist, they could lead to interstellar travel--indeed, to instantaneous access to points at the far range of the universe. They would also confirm both general relativity and the discovery of exotic matter. But curiously little thought seems given to detecting wormholes, or theorizing about how small, stable ones might have evolved since the early universe. Several co-authors and I proposed using the Massive Compact Halo Object (MACHO) searches to reveal a special class--"negative mass" wormholes--since they would appear as sharp, two-peaked optical features, due to gravitational lensing (Physical Review D 51, p3117-20, 1995) So far all the two peaked cases found have been attributed to binary stars or companion planets, though the data fits are not very close.

Surely there could be other ways to see such exotic objects. Some thought and calculations about wormhole evolution might produce a checkable prediction, as a sidelight to an existing search. Further thought is needed about the implications that extra dimensions from string theory will have on wormholes. It seems theoretically plausible that the inflationary phase of the early universe might have made negative mass string loops framing stable Visser-type wormholes.

Perhaps wormholes do not exist. A plausible search that yielded nothing would still be a result, because we could learn something about the possibility of exotic matter. A positive result, especially detection of a wormhole we could reach with spacecraft, could change human history.

Gregory Benford is a professor of physics and astronomy at the University of California, Irvine. His most recent nonfiction is Deep Time.

"What is the pertinent question?"

Surely, the right question it is not what was wrong before Sept.11th. The question mark to be unravelled is why on earth the western productive system has become all-dominant in the general pool of genes, or memes.

The unsolved question is what makes that system so efficient, so all-embracing that no other system or ideology can compete in this planet's race for improving the economic well being per capita. It must be infuriating for beleivers of so called alternative ways, to deal with poverty and collective happiness — in this end of live, I mean, am not talking about afterwards or beyond.

We know a bit about the actual mechanisms of the system — or rather, what economists call aggregate demand. We also infere some of the things which may influence the end product. But no attention is paid to the type of intelligence which is at the roots of the system's survival.

The answer might be that it is a self organizing system based on swarm intelligence. The nearest thing to that are construction setups and organization schemes by social insects like ants, bees and termites: A few, very simple rules, instead of preprogramming and centralized control; the right mixture of robustness and flexibility — just like DNA — hardly any supervising body at all.

Termites of the genus Macrotermes have the added advantage of responding, with due lags, to indirect stimulation from the environment, and not only from other workers. This kind of termites would quickly reduce by half the number of road accidents — the opposite practice of hominids — by diverting traffic towards the railways, just by looking at the death figures.

All this has to do with genetic knowledge. As to non-genetic factors, two are of paramount importance: the separation of State from Religion — it was tantamount to a free entry ticket for everybody in the decision making process — and the neat distinction between Theology and Philosophy (we call it now science); it opened the door to the technological revolution.

Eduardo Punset is Director and Producer of "Networks," a weekly programme of Spanish public television on Science and author of A Field Guide to Survive in the XXI st Century.

"How can a small number of genes build a complex mental machine?"

John McCarthy and I are from different generations (in the semester before McCarthy invented Lisp, he taught my dad FORTRAN, using punch cards on an old IBM) but our questions are nearly the same. McCarthy asks "how are behaviors encoded in DNA"?

Until recently, we were not in a position to answer this question. Few people would have even had the nerve to ask it. Many thought that most of the brain's basic organization arose in response to the environment. But we know that the mind of a newborn is far from a blank slate. As soon as they are born, babies can imitate facial gestures, connect what they hear with what they see, tell the difference between Dutch and Japanese, and distinguish between a picture of a scrambled face and a picture of a normal face. Nativists like Steven Pinker and Stanislas Dehaene suggest that infants are born with a language instinct and a "number sense". Since the function of our minds comes from the structure of our brains, these findings suggest that the microcircuitry of the brain is innate, largely wired up before birth. The plan for that wiring must come in part from the genes.

The DNA does not, however, provide a literal blueprint of a newborn's mind. We have only around 35,000 genes, but tens of billions of neurons. How does a relatively small set of genes combine to build a complex brain? As Richard Dawkins has put it, the DNA is more like a recipe than a blueprint. The genome doesn't provide a picture of a finished product, instead it provides a set of instructions for assembling an embryo. Those instructions govern basic developmental processes such as cell division and cell migration; it has long been known that such processes are essential to building bodies, and it now is becoming increasingly clear that the same processes shape our brains and minds as well.

There is, however, no master chef. In place of a central executive, the body relies on communication between cells, and communication between genes. Although the power of any one gene working on its own is small, the power of sets of genes working together is enormous. To take one example, Swiss biologist Walter Gehring has shown that the gene pax-6 controls eye development in a wide range of animals, from fruit flies to mice. Pax-6 is like any other gene in that it gives instructions for building one protein, but unlike the genes for building structural proteins like keratin and collagen because the protein that pax-6 builds serves as a signal to other genes, which in turn build proteins that serve as signals to still other genes. Pax-6 is thus a "master control gene" that launches an enormous cascade, a cascade of 2,500 genes working together to build an eye. Humans that lack it lack irises, flies that lack it lack eyes altogether. The cascade launched by pax-6 is so potent that when Gehring triggered it artificially on a fruit fly's antenna, the fly grew an extra eye, right there on its antenna. As scientists begin to work out the cascades of genes that build the brain, we will finally come to understand the role of the genes in shaping the mind.

Response to Paul Davies' reply to John McCarthy

It is hard indeed to imagine that nature would endow an organism with anything as detailed as The Cambridge Star Atlas. A typical bird probably has fewer than 50,000 genes, but, as Carl Sagan famously noted, there are billions and billions of stars.

Of course, you don't need to know all the stars to navigate. Every well trained sailor knows that Polaris marks North. A northern-hemisphere dwelling bird known as the Indigo Bunting knows something even more subtle - it doesn't just look for the brightest star (which could be lousy strategy on a cloudy night); instead it looks for how the stars rotate.

Cornell ecologist Stephen Emlen proved this experimentally, by raising buntings in a planetarium. One set of birds never got to see any stars, a second set saw the normal pattern of stars, and a third group saw a sneaky set of stars, in which everything rotated not around Polaris, but around Betelgeuse. The poor birds who didn't see any stars oriented themselves randomly (making it clear that they really did depend on the stars rather than a built-in compass). The birds who saw normal skies oriented themselves normally, and the ones who saw skies that rotated around Betelgeuse oriented themselves precisely as if they thought that Betelgeuse marked North. The birds weren't relying on specific sets of stars, they were relying on the stars' center of rotation.

You won't find the constellations in an indigo bunting's DNA, but you would find in their DNA the instructions for building a biological computer, one that can interpret the stars, taking the skies as its input and producing an estimated direction as its output. Just how the DNA can wire up such biological computers is my vote for the most important scientific question of the 21st century.

Gary F. Marcus is a cognitive scientist at New York University and author of The Algebraic Mind.

"Why do we continue to act as if the universe were constructed from nouns linked by verbs, when we know it is really constructed from verbs linked by nouns?"

My question is to do with materialism, reductionism and the inertia of intellectual progress. It is also connected with the limitations of language as a mechanism for thought or, perhaps more accurately, of thought as a mechanism that defines and constrains language. Above all it is concerned with a 'process' view of the universe, which, although frequently espoused by many of us in this group, still somehow manages to remain trapped inside an older paradigm, like a butterfly that can't quite break free from its chrysalis skin.

It seems to me that we intuitively, linguistically and historically divide the world into tangible things, which we think of as real, and intangible things, to which we usually (or latterly) accord less respect. This is not really a valid distinction since, on closer inspection, all supposedly solid, substantial things turn out to be rather more ephemeral, distributed and transitive than we might like to think. The whole edifice of the universe, it seems, is constructed from interactions between smaller, simpler phenomena that are themselves only patterns of interactions between even simpler phenomena. There are no 'atoms' in the Greek sense. Our division of the world into objects, properties and structures is an artifice to help us deal with it, not a true description of reality. The universe is not divided into hardware and software: there is only software.

Life and Mind are perhaps the most obvious examples of things that subsist as pure process, but atoms, electrons, buildings and societies are in truth no different. To some extent we already know and understand this, and yet I think we can't stop ourselves from dividing hardware from software and treating the former as more real and significant than the latter. Even when we attempt to regard life and mind in a process way we often end up reifying them again as 'information' (as if information were a kind of substance) and end up missing the point.

Perhaps the most incapacitating aspect of our implicit reification of natural phenomena can be seen in a malignant form of reductionism. Benign reductionism — trying to understand something complex by first identifying the properties of its parts — is a valid and powerful tool, often the only one available to science. On the other hand, it often leads implicitly to a belief that something complex can be understood solely in terms of the properties of its parts, without reference to the relationships between those parts. It can easily be demonstrated that this is nonsense (perhaps almost the converse of the truth), and yet much of our present failure to understand nature rests on such a fallacy.

I believe we are edging towards a new paradigm, in which process and interaction — the verbs — are all there is, and material stuff — the nouns — are simply placeholders for more verbs. However, we don't yet have suitable language or mathematics for describing this new viewpoint, and we never will if we fail to recognise the reasons why we so easily slip back into our old ways. Before we can construct something new we must deliberately deconstruct what we have. So the first question I want to ask is: how is our understanding constrained by the apparatus we use for gaining that understanding? After that we can start to discuss what new kinds of language and mathematics might liberate us from this paradigm trap.

Steve Grand is an aritifical life researcher and creator of Lucy, a robot babay orangutan. He is the author of Creation: Life and How to Make It.

"Is the universe a quantum computer?"

The universe is quantum mechanical, and its dynamics can be simulated precisely and efficiently using quantum information processing. The amount of quantum computation required to perform this simulation is finite and has been calculated. Consequently, there is no obvious way to distinguish the universe from a very large quantum logic circuit.

Seth Lloyd is an Associate Professor of Mechanical Engineering at MIT and a principal investigator at the Research Laboratory of Electronics.

"Can wealth be distributed?"

Even with productivity showing startling increases as a consequence of new information technologies everything suggests that the gap between rich and poor is growing dramatically globally and even beginning to increase again in the U.S. So much for trickle down economics.

John Markoff covers the computer industry and technology for The New York Times and is co-author of Takedown: The Pursuit and Capture of America's Most Wanted Computer Outlaw (with Tsutomu Shimomura).

"Is God nothing more than a sufficiently advanced extra-terrestrial intelligence?"

This question is based on what I call, tongue in cheek, "Shermer's Last Law," that any sufficiently advanced extra-terrestrial intelligence is indistinguishable from God.

As scientist extraordinaire (most profoundly as inventor of the communications satellite) and author of an empire of science fiction books and films (most notably 2001: A Space Odyssey), Arthur C. Clarke is one of the most far-seeing visionaries of our time. Thus, his pithy quotations tug harder on our collective psyches for their inferred insights into humanity and our place in the cosmos. And none do so more than his famous three laws:

Clarke's First Law: "When a distinguished but elderly scientist states that something is possible he is almost certainly right. When he states that something is impossible, he is very probably wrong."

Clarke's Second Law: "The only way of discovering the limits of the possible is to venture a little way past them into the impossible."

Clarke's Third Law: "Any sufficiently advanced technology is indistinguishable from magic."

This last observation stimulated me to think more on the relationship of science and religion, particularly the impact the discovery of an Extra-Terrestrial Intelligence (ETI) would have on both traditions. To that end I would like to immodestly propose Shermer's Last Law (I don't believe in naming laws after oneself, so as the good book warns, the last shall be first and the first shall be last): "Any sufficiently advanced ETI is indistinguishable from God".

God is typically described by Western religions as omniscient and omnipotent. Since we are far from the mark on these traits, how could we possibly distinguish a God who has them absolutely, from an ETI who has them in relatively (to us) copious amounts? Thus, we would be unable to distinguish between absolute and relative omniscience and omnipotence. But if God were only relatively more knowing and powerful than us, then by definition it "would" be an ETI! Consider two observations and one deduction:

1. Biological evolution operates at a snail's pace compared to technological evolution (the former is Darwinian and requires generations of differential reproductive success, the latter is Lamarckian and can be implemented within a single generation). 2. The cosmos is very big and space is very empty ("Voyager I", our most distant spacecraft hurtling along at over 38,000 mph, will not reach the distance of even our sun's nearest neighbor, the Alpha Centauri system that it is "not" even headed toward, for over 75,000 years). Ergo, the probability of an ETI who is only slightly more advanced than us and also makes contact is virtually nil. If we ever do find ETI it will be as if a million-year-old "Homo erectus" were dropped into the middle of Manhattan, given a computer and cell phone and instructed to communicate with us. ETI would be to us as we would be to this early hominid — godlike.

Science and technology have changed our world more in the past century than it changed in the previous hundred centuries. It took 10,000 years to get from the cart to the airplane, but only 66 years to get from powered flight to a lunar landing. Moore's Law of computer power doubling every eighteen months continues unabated and is now down to about a year. Ray Kurzweil, in The Age of Spiritual Machines, calculates that there have been thirty-two doublings since World War II, and that the Singularity point may be upon us as early as 2030. The Singularity (as in the center of a black hole where matter is so dense that its gravity is infinite) is the point at which total computational power will rise to levels that are so far beyond anything that we can imagine that they will appear near infinite and thus, relatively speaking, be indistinguishable from omniscience (note the suffix!).

When this happens the world will change more in a decade than it did in the previous thousand decades. Extrapolate that out a hundred thousand years, or a million years (an eye blink on an evolutionary time scale and thus a realistic estimate of how far advanced ETI will be, unless we happen to be the first space-faring species, which is unlikely), and we get a gut-wrenching, mind-warping feel for just how godlike these creatures would seem.

In Clarke's 1953 novel Childhood's End, humanity reaches something like a Singularity (with help from ETIs) and must make the transition to a higher state of consciousness in order to grow out of childhood. One character early in the novel opines that "Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the nonexistence of Zeus or Thor, but they have few followers now."

Although science has not even remotely destroyed religion, Shermer's Last Law predicts that the relationship between the two will be profoundly effected by contact with ETI. To find out how we must follow Clarke's Second Law, venturing courageously past the limits of the possible and into the unknown. Ad astra!

Michael Shermer is the founding Publisher of Skeptic magazine and the author of The Borderlands of Science.

"Is there Progress?"

I work on the question of evolution, not as it exists in Nature, but as a formal system which enables open-ended learning. Can we understand the process in enough detail to simulate the progress of biological complexity in pure software or electronics? A phenomena has appeared in many of my laboratory's experiments in learning across many different domains like game playing and robots. We have dubbed it a "Mediocre Stable State." It is an unexpected systematic equilibrium, where a collection of sub-optimal agents act together to prevent further progress. In dynamical systems, the MSS hides within cycles of forgetting that which has been already been learned.

When a MSS arises, instead of achieving creativity driven by merit based competition, progress is subverted through unspoken collusion. This occurs even in systems where agents cannot "think" but are selected by the invisible hand of a market. We know what collusion is: the two gas stations on opposite street corners fix their prices to divide the market. Hawks on both sides of a conflict work together to undermine progress towards peace. The union intimidates the pace-setter, lest he raise the work standards for everyone else. The telephone company undercapitalizes its own lucrative deployment of broadband, which might replace toll collection. Etc.

As a scientist with many interests in High Technology, of course I know there is progress. I am witness to new discoveries, new technologies, and the march of Moore's law. Clearly, the airplane, long distance communication, and the computer are revolutionarily progressive in amplifying human commerce, communication and even conflict. But these scientific and technological advances stand in stark contrast to the utter depressing lack of progress in human affairs.

Despite the generation of material wealth, health breakthroughs, and birth control methods which could end want and war, human social affairs are organized almost exactly the way they were 500 years ago. Human colonies seem — like ant colonies and dog packs — fixed by our genetic heritage, despite individual cognitive abilities. In fact, it is difficult to distinguish anymore between Dictatorships, Authoritarian Regimes, Monarchies, Theocracies, and Kleptocracies, or even one-party (or two party oscillatory) democracies. When labels are removed, it looks as if authority and power are still distributed in hierarchical oligarchies, arranged regionally. Stability of the oligarchic network is maintained by complex feedback loops involving wealth, loyalty, patronage, and control of the news.

Of course, I'm not against stability itself! But when patronage and loyalty (the collusion of the political system) are rewarded more than competitive merit and excellence, progress is subverted.

The 90's really felt like progress to me, especially with visible movement towards peace in certain regions of the world and an unparalleled creative burst in our industry. But now its like we've just been memory bombed back to the 1950's. The government is printing money and giving it to favored industries. We are fighting an invisible dehumanized enemy. War is reported as good for the economy. Loyalty to the fatherland must be demonstrated. One Phone Company to rule us all. An expensive arms race in space. And law breaking secret agents are the coolest characters on TV.

Havent we been here before? Haven't we learned anything?

Jordan B. Pollack is a computer science and complex systems professor at Brandeis University who works on AI, Artificial Life, Neural Networks, Evolution, Dynamical Systems, Games, Robotics, Machine Learning, and Educational Technology.

"Can there be a science of human potential and the good life?"

Despite monumental advances in brain and behavioral sciences, nothing like a science of human potential and the good life has yet emerged. This seems ironic in an age of unprecedented wealth, yet one that also has chronically high levels of stress and life dissatisfaction.

My hunch is that there's not yet a science of human potential and the good life because such concerns are only just now moving from the realm of humanistic thinking to ones being informed by science. Much of my research lies at the interface between humanities and brain science, as my collaborators and I address basic issues regarding how enduring questions about the quality of human life can be informed by brain science.

In my primary research, I ask, what is the neural basis of human intelligence, and how can our understanding of brain development and plasticity be used to construct more effective learning environments? With Gabrielle Starr, an English professor at NYU and Anne Hamker here at Caltech, we are asking, what is the brain basis of aesthetic experience, and how can such an understanding be used to deepen our emotional life? With Michael Dobry, co-director of the graduate industrial design program at the Art Center College of Design, we are asking, what is the relation between design and the brain, and how can the design of daily life be more in line with the brain's capacities?

Ultimately, a science of human potential and of the good life must help explain how these human capacities can be actualized in contexts that confer significance and dignity to individual life.

Steven R. Quartz is Director of the Developmental Cognitive Neuroscience Laboratory at the California Institute of Technology.

"Why is religion so important to most Americans and so trivial to most intellectuals?"

Is it just a matter of IQ? (Though I thought intellectuals no longer believed in IQ...) But empirically it can't be an IQ issue, because so many of history's greatest minds based their lives on religion — from Michaelangelo or Bach to Spinoza or Dante or Kant. Do modern intellectuals actually believe that all such people are naively deluded? Or could they be missing something themselves?

David Gelernter is a professor of computer science at Yale, chief scientist at Mirror Worlds Technologies and author of Drawiing a Life: Surviving the Unabomber.

"What, me worry?"

This question, which has been asked by many, is now usually attributed to Alfred E. Newman, the poster boy of Mad Magazine. His face tells it all — a composite of attractive merriment and troublesome mindlessness. Who doesn't want to feel like smiling all the time? But at what price?

Psychiatrists know that some people have pathological forms of worry. There are names for this such as obsessive-compulsive disorder and generalized anxiety disorder; and treatments, such as psychotherapy and Prozac. But what about the rest of us? What is the optimal balance between worry and contentment? Should we all be offered some kind of training to help us achieve this optimal balance? And how should we apply our growing understanding of the brain mechanisms that control these feelings?

Samuel Barondes is a professor and director of the Center for Neurobiology and Psychiatry at the UC-San Francisco and author of Mood Genes: Hunting for Origins of Mania and Depression.

"What is the missing ingredient — not genes, not upbringing — that shapes the mind?"

We know that genes play an important role in the shaping of our personality and intellects. Identical twins separated at birth (who share all their genes but not their environments) and tested as adults are strikingly similar-though far from identical-in their intellects and personalities. Identical twins reared together (who share all their genes and most of their environments) are much more similar than fraternal twins reared together (who share half their genes and most of their environments). Biological siblings (who share half their genes and most of their environments) are much more similar than adopted siblings (who share none of their genes and most of their environments).

Many people are so locked into the theory that the mind is a Blank Slate that when they hear these findings they say, "So you're saying it's all in the genes!" If genes have any effect at all, it must be total. But the data show that genes account for about only about half of the variance in personality and intelligence (25% to 75%, depending on how things are measured). That leaves around half the variance to be explained by something that is not genetic.

The next reaction is, "That means the other half of the variation must come from how we were brought up by our parents." Wrong again. Consider these findings. Identical twins separated at birth are not only similar; they are "no less" similar than identical twins reared together. The same is true of non-twin siblings — they are no more similar when reared together than when reared apart. Identical twins reared together — who share all their genes and most of their family environments-are only about 50% similar, not 100%. And adopted siblings are no more similar than two people plucked off the street at random. All this means that growing up in the same home — with the same parents, books, TVs, guns, and so on — does not make children similar.

So the variation in personality and intelligence breaks down roughly as follows: genes 50%, families 0%, something else 50%. As with Bob Dylan's Mister Jones, something is happening here but we don't know what it is.

Perhaps it is chance. While in the womb, the growth cone of an axon zigged rather than zagged, and the brain gels into a slightly different configuration. If so, it would have many implications that have not figured into our scientific or everyday way of thinking. One can imagine a developmental process in which millions of small chance events cancel one another out, leaving no difference in the end product. One can imagine a different process in which a chance event could derail development entirely, making a freak or monster. Neither of these happens. The development of organisms must use complex feedback loops rather than blueprints. Random events can divert the trajectory of growth, but the trajectories are confined within an envelope of functioning designs for the species defined by natural selection.

Also, what we are accustomed to thinking of as "the environment" — namely the proportion of variance that is not genetic — may have nothing to do with the environment. If the nongenetic variance is a product of chance events in brain assembly, yet another chunk of our personalities and intellects would be "biologically determined" (though not genetic) and beyond the scope of the best laid plans of parents and society.

Steven Pinker, research psychologist, is professor in the Department of Brain and Cognitive Sciences at MIT and author of Words and Rules.

"When will our souls be upgraded?"

If, as Harold Bloom puts it, Shakespeare invented the modern soul, if we are the way we are because Shakespeare existed as a writer, the question arises, whether this historic progression has come to an end and will soon be replaced by a new version of 21st century souls.

The Shakespearean soul will not be able to cope with the innovations and insights of the near future. Star Wars, Star Trek, even Gibson might prove unrealistic — not because of their description of hardware, but because of their description of the soul.

Frank Schirrmacher is Publisher, Frankfurter Allgemeine Zeitung and author of Die Darwin AG.

"Is it conceivable that the standard curriculum in science and math, crafted in 1893, will still be maintained in the 26,000 high schools of this great nation?"

The world is caught up in a paroxysm of change. Key words: globalism, multinational corporations, ethical influences in business, explosive growth of science-based technology, fundamentalism, religion and science, junk science, alternative medicines, rich vs. poor gap, who supports research, where is it done, how is it used, advances in cognition science, global warming, the disconnect between high school and college....these and other influences are undergoing drastic changes and all will have some impact on science, mathematics and technology and therefore on how our schools must change to produce graduates who can function in the 21st century...function and assume positions of leadership. Is it conceivable that the standard curriculum in science and math, crafted in 1893, will still be maintained in the 26,000 high schools of this great nation?

This is a question that obsesses me in my daily activities. I have been agonizing over it along with a few colleagues around Fermilab, University of California, and the students, staff and trustees of the Illinois Math Science Academy (IMSI), a three year public residential high school for gifted students, I was involved in founding some 16 years ago.

Is not our nation even more at risk now than ever? Are not our 2 million teachers even more poorly trained now, even less respected, hardly better compensated than when we were A Nation at Risk? Some 13 years ago, the collected Governors of the United States under the leadership of the President made six promises, all starting with: "By the year 2000 all students will....".

The rhetoric varies from high comedy to dark tragedy. Today, the Glenn National Commission summarizes its dismal study of science and math education in a succinct title: Before its Too Late. Alan Greenspan mesmerizes a congressional panel on Education and the Work Force with the warning that if we do not radically improve our educational system, there is a danger to the future of the nation. Words carefully chosen. Rhetoric. We have no national strategy to address this question. In a war on ignorance and on looming changes of unknowable dimensions, shouldn't we have a strategy?

Leon M. Lederman, the director emeritus of Fermi National Accelerator Laboratory, has received the Wolf Prize in Physics (1982), and the Nobel Prize in Physics (1988). He is the author (with Dick Teresi)of The God Particle: If the Universe Is the Answer, What Is the Question?

"In view of globalization, which is here to stay, and the events of September 11and its aftermath, which were a shock to most of us, do we need to make fundamental changes in our educational goals and methods?"

Precollegiate education has been remarkably consistent over the decades: literacy in the primary years, initial mastery of a few major subject areas (math, science, history, language, perhaps in the arts) in middle and secondary school. We could take the position that we know how to do this and should just stick to our guns. I don't agree.

Because of globalization, the capacity to think across disciplines, to synthesize wide ranges of information efficiently and accurately, to deal with individuals and institutions with which one has no personal familiarity, to adjust to the continuing biological and technological revolutions, are at a far greater premium. And because of the events of September 11, we need to think much more deeply about the nature of democratic institutions and the threats to them, the role and limits of tolerance and civil liberties, the fate of scarce resources, profound gaps across religions and cultures, just to name a few.

The time has come where we need to rethink what we teach, how we teach, what young people learn on their own, how they interact, how they relate to mass culture, etc. The question we must then ask is: Do we have to continue to be reactive or can we plan proactively the education that is needed for our progeny in this new world?

Howard Gardner is Professor of Cognition and Education at Harvard University at the co-author (with Mihaly Csikszentmihalyi and William Damon) of Good Work: When Excellence and Ethics Meet.

"When is it time to stop calculating risk and rewards, and just go ahead and do what you know is right?"

In the world we live in, mathematicians and investors have become ever better at calculating risks, assessing outcomes, laying out possible scenarios. But real economic progress comes from taking challenges, not risks, and building something fantastic *despite* the odds, because you know you're smarter and more dedicated and more persistent, and you can gather and lead a better team, than any rational calculation would indicate. That's how new businesses get built, new markets get opened, new value gets created.

And real political, social and ethical progress, likewise, comes not just from negotiating a carefully calibrated "win-win" balance-of-power compromise, matching move for move, but from taking the lead, challenging the other guy to follow, showing the way forward. We make progress by stretching the imagination and doing things we won't regret. When you cannot predict consequences, then you need to consider your conscience and do what's right.

We need not calculation, but courage!

Esther Dyson is president of EDventure Holdings and editor of the computer-industry newsletter, Release 1.0, and author of the book, Release 2.1: A Design for Living in the Digital Age.

"The hows and whys of what led to us"

There are, it seems to me, just two fundamental scientific questions that, for very different reasons, we may have no possibility of answering with any certainty.

One question is so fundamental that it is arguably not a scientific question at all: It's the big how and why question of existence itself. Although there are many technical questions still to be answered, as a mathematician, I find myself broadly content with science's explanation of how the physical universe — including time itself — sprang into being: the symmetry breaking, primordial fireball we call the Big Bang, followed by the subsequent evolution into the universe we see today. But that is simply an explanation of the mechanics of the universe of our experience and perception. It leaves us with a lingering question of how, and perhaps why, the framework arose in which the Big Bang took place in the first place — be that framework one in which our universe is the only one there is and has ever been, or one that cycles in "universe time" (whatever that is), or maybe some kind of multiple universe scenario.

I accept that this is not really a scientific question. Science only addresses the how of our own universe, starting just after the Big Bang. But my curiosity, both as a scientist and more generally just as a thinking person, cannot help but dwell from time to time on the biggest question of all — the question that for those having a deep religious faith seems to find an answer in the phrase "God made it that way." (An answer that I find even more incomprehensible in a world where millions of human beings believe that that same God authorizes his chosen emissaries to fly jet airliners full of humans into buildings full of other humans.)

My second fundamental question is clearly a genuine scientific matter. In fact, it is a technical question about evolution by natural selection. Exactly how and why did a species (namely, us) develop that has the capacity to think abstractly, that possesses language, and that can reflect on its own existence? Like the big existence issue, this is a question that has enormous significance for us, as humans. And that makes it the more frustrating that we may find ourselves unable ever to answer it with any certainty.

In my recent book The Math Gene, I summarized arguments to show that the possession of language (i.e., a symbolic communication system with a recursive grammatical structure allowing for the production and comprehension of meaningful utterances of unlimited length) and the ability for "offline" thinking (reasoning about the world in the absence of direct input from the environment and without the automatic generation of a physical response) are two sides of the same coin. Implicit in that argument is that this ability also brings with it the capacity for self-reflective, conscious thought. (I also argued that such a mental capacity also yields the potential for mathematical thought.) Thus, we are talking here about the capacity that makes us human, and in so doing makes us very different from any other species on Earth.

The best evidence we have from anthropology is that our ancestors acquired this capacity some time between 75,000 and 200,000 years ago. (The evidence is in the form of manufactured artifacts that early humans left behind, which indicate such a level of abstract thinking and communication.) But how — and in terms of natural selection, why — did our ancestors acquire this capacity? All we know for sure is that it came at the end of a three-and-a-half-million year period in which the average brain size of our ancestors grew to roughly its present level, approximately nine times larger than is normal for a mammal of our body size and about twice that of a present-day ape.

What makes this question particularly hard is that, at least in terms of functionality (as opposed to brain structure), the acquisition of syntactic structure (i.e., the structure that enables us to create complex sentences or to reason abstractly about the world) is an all-or-nothing event. As linguists have pointed out, you cannot have "half a grammar". True, in theory you can have grammars without, say, passive constructions, but there is no chain of gradually more complex grammars that starts with protolanguage — simple subject-predication utterances — and leads continuously to the grammatical structure that is common to all human languages. The chain has to start with a sudden jump. Although the acquisition of language was a major functional change in brain capacity, there is no reason why that jump was not the result of a tiny structural change in the brain. But what propelled the brain to reach a stage where such a change could occur? And what exactly was that small structural change? This would surely be a minor technical question about one detail, among thousands, of evolutionary history, were it not for the fact that it was this single change that made us human — that made it possible for us to ask these how and why questions, and to care about the answers.

One oft-repeated suggestion for the natural selection advantage that language provides is that it enabled the communication of more complex thoughts and ideas than was previously possible. But that suggestion falls down immediately when you realize that such communication can only arise when the brain that is doing the communicating is able to form those complex thoughts and ideas in the first place, and that capacity itself requires a brain having grammatical structure.

It seems likely that the two sides of this particular coin, thinking complex thoughts and communicating them, arose at the same time, and indeed it could have taken both aspects together to spur the development that led to their acquisition. But we are still left with the tantalizing question that the obvious natural selection advantages this capacity provides only came into play after the capacity was in place. Just what led to and prompted that jump remains a mystery.

There has been, as you might imagine, no shortage of attempts to provide an explanation, but so far I haven't seen one that I find convincing, or even close to convincing. (I mention some in The Math Gene, and give pointers to further reading on the matter.) And even if someone produces a compelling explanation, it seems we will never know for sure. When our early ancestors died, their brains rapidly rotted away, leaving nothing but the skulls that contained them. And even if, by some fluke, we found an intact brain from some early ancestor, buried deep in the ice of a glacier somewhere, how could that help us? Dissecting an object as complex as the human brain tells us virtually nothing about what that brain did — how it thought and what it thought about.

Our higher brain functions could just have been an accident. Of course, all evolutionary changes are accidents. What I mean here is that it may be purely accidental that the structural change in the brain that gave us language and abstract, symbolic thought did in fact have that effect. It might just be, as some have suggested, that the brain grew in complexity as a device for cooling the blood, and that language and symbolic thought are mere accidental by-products of the body's need to maintain a certain temperature range. (Certainly, the brain is an extremely efficient cooling device, as illustrated by the fact that putting on a hat is an extremely efficient way of staying warm when we go skiing.) Personally, I don't buy the cooling mechanism explanation. But unless and until someone comes up with something more convincing, I see no way we can rule it out.

For all our huge success in telling the story of how life began and evolved to its present myriad of forms, it seems likely that we may never know for certain exactly what it was that gave us the one thing we value above all else, and the thing that makes us human: our minds. If there is one question I would like to answer above all others, it is this one.

Keith Devlin, mathematician, is a Senior Researcher at Stanford University, and author ot The Math Gene.

Plato believed that human knowledge was inborn. Kant and Peirce agreed that much of knowledge had to exist prior to birth or it would be impossible to understand or learn anything. Until quite lately, psychologists were almost uniformly opposed to this notion, insisting that only process not content could be part of our native equipment. Piaget was typical (and highly influential) in asserting that only learning skills and inferential procedures such as deductive rules and schemes for induction and causal analysis were native. He also maintained that these were identical for all people with undamaged minds, and that development of such processes ended with adolescence. Content could be almost infinitely variable because these processes operate on different inputs for different people in different situations and cultures.

But recent work by psychologists provides evidence that some content is universal and native. Theories of mechanics are present by the age of three months and highly elaborated theories of mind and make their appearance before the age of four, are universal, and may also be native. Some anthropologists maintain that schemes for understanding the biological world and even some for understanding the social world are universal and native, as are some knowledge structures for representing the spirit world.

Psychologists ­ and philosophers in this case as well ­ may turn out to be wrong in assuming that all mental processes are universal, native and unalterable. Though early in the 20th century there were claims by Soviet psychologists Vygotsky and Luria that cognitive processes were historically rooted, differentiated by culture, and alterable by education, they were largely ignored. But findings have cropped up from time to time that fit these assertions. Deductive rules may be a trick learned in the process of Western-style education; rational choice procedures may be applied primarily by economists and only in very limited domains by lay people; statistical rules (Piaget's "probability schema") may be used only to a very slight extent by non-Western peoples.

Authors of this year's questions have asked how radical the differences among universes, mathematical systems, and kinds of life might be. How radical could the differences among humans be in basic knowledge structures and inferential procedures? What has to be shared or even inborn? What can be allowed to vary?

Richard Nisbett is Professor of Psychology and Co-Director of the Culture and Cognition Program at the University and author numerous books.

As any parent of adolescents has probably experienced, life has become sufficiently complex that emotional maturity by the end of teen years is a thing of the distant past. If adolescence would only be over by 25!

More seriously, for democracy to function representatives need to make critical value trade-offs for citizens. But how can citizens send messages on how they would like their values to drive policies when the issues are so complex that very few citizens — and not too many politicians either — really understand enough of what might happen and at what probabilities to know how to make decisions that do optimize the value signals from citizens.

The ultimate in irrationality is to make a decision that doesn't even advance your values because the situation is so complex that the decision makers — or the public — can't see clear connections between specific policies and their potential outcomes (as one who works on the global warming problem I see this conundrum all the time).

The capacity to be literate about scientific and political establishments and their disparate methods of approaching problems is a good start, but such literacy is not widespread and the complexity of most issues sees public and decision-makers alike disconnected from core questions. Educational establishments often call for more content in curriculum to redress this issue, but I think more understanding of context of scientific debate and political and media epistemologies will go further to build the needed literacy.

Stephen H. Schneider is Professor in the Biological Sciences Department at Stanford University and author of Laboratory Earth.

The question of what is "real," defined here as the physical universe, acquires special subtlety from the perspective of brain and cognitive science. The question goes beyond semantic quibbling about the difference between physical stimuli and our perception of them. (Consider the old question, "If a tree falls in the forest, was a sound made if no one is present to hear it?" The answer is "no," because a sound is a sensation that must be perceived by an observer, and no observer was present to hear it.) The startling truth is that we live in a neurologically generated, virtual cosmos that we are programmed to accept as the real thing. The challenge of science is to overcome the constraints of our kludgy, neurological wetware, and understand a physical world that we know only second-hand. In fact, we must make an intuitive leap to accept the fact that there is a problem at all. Common sense and the brain that produces it evolved in the service of our hunter-gatherer ancestors, not scientists.

Sensory science provides the most obvious discrepancies between the physical world and our neurological model of it. Consider these physical to perceptual transformations: photons stimulate the sensations of light and color; chemicals produce tastes and odors; and pressure changes become sounds. Yet, there is no "light" or "color" in the wave or photon structure of electromagnetic radiation, no "sweet" in the molecular structure of sugar, no "sound" in pressure changes, etc. The brain produced these sensory attributes. Sensation is the arbitrary experience that is correlated with a physical stimulus, but is not the physical stimulus itself. Our brain manages these psychophysical transformations in such a convincing manner that we seldom consider that we are sensing a neurological simulation, not physical reality. When do we question the physical meaning of "blue," "pain," or "B-flat?" Consider also the apparent seamlessness of the reality illusion. Using a visual metaphor, our sensory environment is like that of a person trapped in a tiny house, through which the universe must be viewed through peep-holes, one per each sensory channel, such as vision, taste, hearing, etc. From this limited, peep hole vista, we synthesize a seamless, noisy, bright, flavorful, smelly, three dimensional panorama that is an hypothesis of reality. The peep-hole predicament is invisible to us. (Some animals have peep-holes we lack, such as those associated with electric or magnetic field perception.)

Sensory examples are instructive because the nature of the psychophysical linkage is relatively clear. It's easy to imagine sensory limits of bandwidth (the size of our "peephole"), absolute sensitivity, or even modes of sensitivity (our "peep-holes"). Neurological limits on thinking may be as common as those on sensing, but they are more illusive — it's hard to think about what you can't think about. A good example from physics is our difficulty in understanding the space-time continuum — our intellect fails us when we move beyond the dimensions of height, width, and depth. Other evidence of our neurological reality-generator is revealed by its malfunction in illusions, hallucinations, and dreams, or in brain damage, where the illusion of reality does not simply degrade, but often splinters and fragments.

Why am I interested in this question? As a neuroscientist, I want to understand how the brain evolved, developed, and functions. As a biologist, I believe that all organisms are a theory of their environment, and it's necessary to understand that environment. As an amateur astronomer and cosmologist, I want to know the universe in which I live. To me, physics, biology, neuroscience and psychology are different approaches to a similar set of perceptual problems. It's no coincidence that Herman Helmholtz, a great physicist of the past century, appreciated that you can never separate the observer from the observed, and became a founder of experimental psychology. The distinction between psychology and physics is one of emphasis. The time has come for experimental psychologists to return the favor and remind physicists that they should be wary of confusing the physical world with their neurologically generated model of it. The frontiers of physics may be an exciting playground for the adventurous cognitive scientist. Ultimately, physics is a study of the behavior of physicists, scientists trying as best they can to understand the physical world. The intellectual prostheses of mathematics, computers, and instrumentation loosen but do not free our species of the constraints of its neurological heritage. We do not build random devices to detect stimuli that we cannot conceive, but build outward from a base of knowledge. A neglected triumph of science is how far we have come with so flawed an instrument as the human brain and its sensoria.

Robert R. Provine is Professor of Psychology and Neuroscience at the University of Maryland and author of Laughter: A Scientific Investigation.

"Is there, or should we expect, a fracture in the logical basis on which people now look for a description of the nexus between particle physics and cosmology?"

Question: Since the 1930s, we have had to live with Godel's theorem — the apparently unshaken proof by the logician Kurt Godel that there can be no system of mathematical logic that is at once consistent (or free from contradictions) and complete (in the sense of being comprehensive). The question is whether there is, or whether we should expect, such a fracture in the logical basis on which people now look for a description of the nexus between particle physics and cosmology.

Why: The chief interest of Godel's theorem is that it is a negative answer to one of the questions in David Hilbert's celebrated list of tasks for the twentieth century, put forward at the International Mathematics Congress in Paris in 1900. Mathematicians in the succeeding century seem not to have been unduly incommoded by Godel. But if there were a comparable theorem in fundamental physics, we should have more serious difficulties. Perhaps the circumstance that string theory is getting nowhere (not fast, but slowly) should be taken as a premonition that something is amiss. The search for a Theory of Everything (latterly gone off the boil) may be logically the wild goose chase it most often seems. If science had to abandon the principle that to every event, there is a cause (or causes) , the cat would really be among the pigeons.

Moral: Godel's theorem needs seriously to be re-visited, so that the rest of us can properly appreciate what it means.

Sir John Maddox who recently retired having served 23 years as the editor of Nature, is a trained physicist, and author of What Remains to be Discovered: The Agenda for Science in the Next Century.

The most remarkable aspect of quantum theory is its relational character: elementary quantum events (such as a certain quantum particle being "here") only happen in interactions, and, in a precise sense they are only "real" with respect to, or in relation with, another system. Indeed, I can see the particle "here", but at the same time the particle and I can be in a quantum superposition in which the particle has no precise localization. Thus, a quantum particle is not just "here", but only "here for me".

On the other hand, the most remarkable property of general relativity is that localization in space and time are not defined. Things are only localized with respect to other things. In fact, the spacetime coordinates have no meaning in general relativity, and only quantities that are independent of these coordinates (such as relative localizations) have physical meaning.

Now the question is: are the quantum relationalism (quantum systems have definite properties only in nteracting with other systems) and the general relativistic relationalism (position is only relative) connected to each other? Are they indeed two aspects of the same relationalism?

There is clearly some deep connection. In order to interact quantum mechanically, two systems must be close in space and time, and, viceversa, spacetime contiguity can only be checked via a quantum interaction. So, is perhaps spacetime just the geography of the net of the quantum interactions? Is the world just made of relations?

We are far from understanding all this, and the current highly speculative physical theories haven't even started addressing this kind of questions. But until we address these questions -which are the interesting ones in physics for me- the great revolution of the 20th century is not over. We have lost the old picture of the physical world, but we haven't a new credible one yet.

Carlo Rovelli is a theoretical physicist at the Centre de Physique Theorique in Marseille, France.

Many human skills enable an individual to do something with less physiological effort. If you are good at skiing (and I am not) it takes less energy to climb that mountain. One can even argue forcefully that a mental "understanding" of a phenomenon allows one to perceive it with less increase in brain metabolism.
But not all skills are directed at a reduction of the expenditure. Many creative activities involve a huge effort to explore new issues or phenomena. The better skier goes beyond the first mountain. New worlds and ideas are explored. Why do we bother — or why do some of us bother?

One could argue that we explore new phenomena to produce skilful insights that will in the future allow us to visit the same phenomena again with less effort. But is that really enough? Can such a functional explanation of creativity as an initial effort devoted to enable a future reduction of the effort really capture the reasons for people to involve themselves in lifelong efforts to understand the world of ants or the intricacy of ski dope?

It seems that president John F. Kennedy captured an essential element in creative efforts when he, in his famous speech at Rice University in 1962, argued for the decision to create the Apollo program: "We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills..."

Indeed, the most important outcome of Apollo — offering earthlings an outside view of their planet, visualizing the vulnerability of the Earth and its biosphere — was an unintended result of doing a major effort. It did pay off to do something hard. Somehow we know that doing something hard, rather than something easy, is fruitful. But we also know that doing it the hardest way possible (like when I ski) is not a very efficient way of getting anywhere.

We want to be efficient, but also to do difficult things. Why? In a sense this is a rephrasing of Brian Eno's question in Edge 11: "Why Culture"? Many different approaches can be taken involving different disciplines such as economy, anthropology, psychology, evolutionary biology etc.

An idea currently explored in both economy and evolutionary biology could be relevant: Costly signals. They provide the answer to the question: How does one advertise one's own hidden qualities (in the genes or in the bank) in a trustworthy way? By giving a signal that is very costly to produce. One has to have a strong bank account, a very good physiology (and hence good genes) or a strong national R&D programme to do costly things. The more difficult, the better the advertising.

Perhaps we bother because we want to show that we are strong and worthy of mating? Culture is all about doing something that is so difficult that only a healthy individual or society could do it.

If so, it's not at all about reducing the effort, it's all about expanding the effort.

Tor Nørretranders is a science writer, consultant, lecturer and organizer based in Copenhagen, Denmark and author of The User Illusion: Cutting Consciousness Down to Size.

"Why do people kill other people?"

No offense against another human being inflicts greater costs than killing. Simply put, it's bad to be dead. Nonetheless, hundreds of thousands are murdered every year; tens of millions over the past century. From baby killing to genocide, from Susan Smith to Osama bin Laden, people in every culture experience the urge to kill. Some act on it. They do so despite legal injunctions, religious prohibitions, cultural interdictions, the risk of retaliation, and the threat of spending life in a cage. Dead bodies, a trail of grief, and a thirst for vengeance lie in their wake.

Many believe that they already know the answer to the question of cause. But existing theories woefully fail to explain why people murder. Theories that invoke violent media messages, for example, cannot explain the high rates of homicide among tribal cultures that lack media access. Theories that invoke uniquely modern causes cannot explain the paleontological record — ancient skulls and skeletons that contain arrow tips, stone projectiles, and brutally inflicted fractures. The stones and bones of the past leave no doubt that murder has been a persistent problem of social living throughout human history. We need to understand why.

David M. Buss is Professor of Psychology at the University of Texas, Austin, and author of Evolutionary Psychology: The New Science of the Mind.

"What is the difference between the sigmundoscope and the sigmoidoscope? Less cryptically, how is everyday narrative logic different from extensional mathematical logic?

It differs in countless ways, most of them poorly understood. It generally deals with individuals rather than analyses or averages, with motives and reasons rather than movements and causes. It has a point of view rather than a "view" from nowhere. As the writer's maxim says, it shows rather than tells, contains dialogue rather than only declarative sentences, relies on context rather than raw data alone, is open-ended and metaphorical rather than determinate and literal, is tied to a particular time rather than being timeless, and deals with emotions rather than impersonal facts. Furthermore, narrative logic must deal with the notion of "common knowledge," whereby two or more people know something, know that the others know it, know that the others know that others know, and so on. In short, narrative logic is much harder than mathematical logic.

In everyday "story logic," how "we," the story-tellers, characterize an event or person is crucial. If a man touches his hand to his eyebrow, for example, we may see this as an indication he has a headache. We may also see the gesture as a signal from a baseball coach to the batter. Then again, we may infer that the man is trying to hide his anxiety by appearing nonchalant, that it is simply a habit of his, that he is worried about getting dust in his eye, or indefinitely many other things depending on indefinitely many perspectives we might have and on the indefinitely many human contexts in which we might find ourselves. A similar open-endedness characterizes the use of probability and statistics in surveys and studies.

Furthermore, unlike mathematical logic, story logic does not allow for substitutions. In mathematical contexts, for example, the number 3 can always be substituted for the square root of 9 or the largest whole number smaller than the constant without affecting the truth of the statement in which it appears. By contrast, although Lois Lane knows that Superman can fly, and even though Superman equals Clark Kent, the substitution of one for the other can't be made. Oedipus is attracted to the woman Jocasta, not to the extensionally equivalent person who is his mother. In the impersonal realm of mathematics, one's ignorance or one's attitude toward some entity does not affect the validity of a proof involving it or the allowability of substituting equals for equals.

John Allen Paulos is Professor of mathematics at Temple University adjunct professor of journalism at Columbia University, and author Once Upon a Number.

"How much can we expect the social sciences to help build a just and free society?"

Marx and Engels argued for "scientific socialism", that is, for a political movement that would bring about a just and free society with the help of science. No need to recall how the movements that they inspired either failed to achieve much, or succeeded in establishing societies tragically lacking in justice and freedom. Was the science insufficiently scientific, or was the very idea of a scientific socialism flawed? I became a social scientist (and then a cognitive scientist and a philosopher) out of the conviction that what was lacking in scientific socialism was a proper science of society. I gave myself the goal of contributing to the development of a truly scientific programme in the social sciences. Today, I believe some significant steps have been taken in this direction, in particular by beginning to bridge the gap between the social sciences and the cognitive and, more generally, the natural sciences. But does this bring us anywhere nearer, not "scientific socialism" (clearly an obsolete notion), but, more generally, the possibility of using the social sciences for radically bettering our world?

Most people understand the social relationships and institutions in which they participate well enough to get the most (which often is not much) out of their participation. The social sciences are, for the most part, a systematized, de-parochialized, professionalized version of this competence that we all have, to a smaller or greater extent, as social actors. As such, the social sciences help us improve our understanding of the social world; they help better understand in particular the point of views of other actors in the same society and of people in other societies. But this enhanced understanding is still shallow, and strikingly weak in predictive power. It is, as far as informing political action, little more than serious journalism without the time pressure. The events of last September provide a telling illustration: What did social scientists have to contribute to our understanding of the events? Did interpretive anthropologists provide a much deeper understanding of the fundamentalist terrorists? Did sociologists give well argued and unexpected predictions as to how the target societies would react? No, the contribution of social scientists was, to say the least, modest. Still, the role of the social sciences as enhancers of common sense social understanding may be modest, but it is crucial in helping people overcome prejudices and biases, and become better citizens not just of their own country, but of the world. Immodest social scientists that presume say what is to be done should not be easily believed.

But might, in the future, a more scientific social science emerge (probably alongside, rather than in place of, the more common sense social sciences that we know)? Its role would not be to ground political action — it is not the role of science to say what is good and what is bad — but to inform it well enough so that more daring long-sighted political action could be undertaken — action that might help build a more just and freer society —without being all too likely to have its unforeseen consequences compromise its initial goals, as happened with communism? This is my question. I don't know the answer.

Dan Sperber is a social and cognitive scientist at the French Centre National de la Recherche Scientifique (CNRS) in Paris and author, with Deirdre Wilson, of Relevance: Communication and Cognition.

"Why do people like music?"

People from every culture like listening to some kind of music, so it seems that it is something that is wired into us. Is there an evolutionary advantage to liking music?

W. Daniel Hillis is Chairman and Chief Technology Officer of Applied Minds, Inc., a research and development company and author of The Pattern on the Stone.

"Why do we decorate?"

Why do all the human cultures that we know of decorate things? Why not just leave them alone? Why put in all that extra, and apparently non-functional, energy?

Brian Eno, an artist, makes and produces records. He has produced U2 ("including this year's award- winning "All That You Can't Leave Behind"), Talking Heads and Devo and collaborated with David Bowie, John Cale, and Laurie Anderson.

"Will unification ever come to a stop?"

Unification of opposites is an underlying theme in the development of humanity. Newton showed us that the same laws govern the motion of heavenly bodies and apples falling on Earth. Darwin unified the concept of being a human with that of being another living organism. There have been numerous other unifications in the history of mankind. So, how will it go on? Which notions appearing to us as very distinct today will turn out to be the same for future generations? Will there ever be a limit to unification? Will we in the end be able to show that everything just stems from one single fundamental idea? Or two? Or many? Or infinitely many?

A more practical and immedite question is where the next step will lead us to? Which is the next unification of seemingly opposite and distinct concepts. Maybe we should look at the real big questions loom today and take them as hints for the next unifications. So, very specifically, which of the questions raised in the Edge World Question drive points towards the next unification?

Anton Zeilinger is a Professor of Physics at the University of Vienna whose work in quantum teleportation has received world-wide attention.

"Is the PC desktop really dead?"

Much ado has been made lately over the problems of the PC "desktop metaphor," the system of folders and icons included in Macintosh and Windows PCs. Critics of the desktop rightly point out that today's PC users encounter much more information than in the 1980s, when the desktop was first introduced. While I understand these criticisms, I question whether the desktop is really dead ‹ in other words, whether the solution really lies in building a better desktop. Instead, I think that the real issue is the increased information, not the interface between it and the user.

Some technologists are ready to discard the old desktop. Last month MIT's Technology Review ran a piece on new software attempting to bypass the desktop metaphor. None of the tools are very convincing. Scopeware, a software package from Mirror Worlds Technologies (founded by David Gelernter, an Edge contributor), essentially removes all file hierarchy by showing files sorted by creation date. While the tool has some nice search features, it's unclear how removing all file hierarchy is an improvement over today's desktop. Other technologies in the article include a two-dimensional graphical "map" of the file system and a 3-D navigable space. These programs try to solve the problem of a cluttered desktop by presenting a new metaphor that could become just as cluttered.

To be sure, there are advances to be made in the tools. Using Microsoft Windows, even briefly, reveals so many interface flaws that it makes me cringe. But fixing these myriad flaws will not address the central issue, which is the tsunami of information arriving into users' PCs. It is the user, not the tool, that should be the focus.

The Wall Street Journal recently interviewed several Americans to inquire about their personal strategies for dealing with their e-mail. Receiving 50 to 150 incoming messages per day, these PC users described the methods they use to stay on top of their information and remain effective in their jobs.

What's interesting about this article is that the Journal recognized e-mail use as a personal activity. Many other business activities, like using approved software or submitting timesheets, may be closely regulated by the IT department ‹ but not e-mail. Each user in the article has become conscious of his or her information flow and has created a system to manage it, using the software (albeit flawed) at his or her disposal. The story is about personal needs first, tools second. The industry's response to this problem should be the same. If we could just teach more users to use their tools better, we'd be in far better shape than if we simply churned out yet more complex software.

I would be happy to be proven wrong. Gelernter's Scopeware, for example, could turn out to be a revolutionary advance in curing information anxiety. My guess, however, is that even the best tools will fall short of a cure. We may need a combined strategy of better tools and greater education of users about the nature of a world awash in information. To be effective in coming years, users must assume greater responsibility for their own information management.

Of course, there are problems with that proposition. For one, new desktop metaphors, like the 3-D software, is sexy and makes for interesting press clips. Educating users is decidedly dull. What's worse, there is no easy business plan to educate users en masse in more efficient ways to organize their information. Making a tool that promises to help is so much more profitable. But tools alone won't save us. If all we can do for users is give them a newer, flashier, more distracting interface, then the desktop may indeed be dead forever.

Mark Hurst is the founder of Creative Good, Inc., a leading user experience consulting firm.

" Does life on Earth have a future?"

By "life on Earth" I mean the variety of life, the multitude of species, the dazzling array of ecosystems they create from the permanent snow fields of the Himalayas to steamy jungles, and coral reefs, and the variety of including ourselves including and the 6000+ languages we speak and our cultures that they largely define.

There are two answers: no and yes.

A median estimate is that a third of all the species will be on the fast track to extinction within the next quarter century. Over 90% of all languages will be gone by then, because languages spoken by fewer than a million people are rarely taught to children. Most tropical forests will be gone by 2025 and with them, their species and peoples. Global warming will ensure that the species that survive do so in the wrong place. Coral reefs will be cooked alive in too-warm oceans, tropical glaciers will long have been only a memory preserved in the National Geographic photo collection.

So what will it mean for humanity to live in such a biological impoverished world? I always think of Orange County, California, with an airport named after an actor. A fake cowboy/war hero (delete as appropriate) to introduce you to a desert world with nitrogen-enriched green lawns, no sidewalks, golf courses, imported water. Instant gratification reigns. The future? Don’t worry be happy. Enough people like that world; property values are high.

But suppose we saved the variety of life on Earth, grabbed the nettle of global warming, and, in general thought about our human futures. What would that tell us about ourselves — and what we are capable of achieving? What would it take to accomplish that?

Answer the life-on-Earth question and whatever answer one picks, so much about ourselves must be revealed.

Stuart Pimm is Professor of Conservation Biology at Columbia University in New Yorkand author of The World According to Pimm: A Scientist Audits the Earth.

"Is it possible to know what is good and what is evil?"

For the past four centuries, the attempt to answer this question has been the main driving force of world history ­ not only the history of ideas, but also the history of politics and collective violence. This is true for two reasons:

1. It is impossible for people to live without constructing some cognitive structure (which philosophers call practical reason) that asks and answers questions concerning how to live and what to do ­ traditionally, by formulating them in moral or ethical terms as how we should live and what we ought to do.

2. When humanity made the transition, at the time of the scientific revolution of the 17th century, to a new and higher stage of its collective cognitive development by progressing from theology and philosophy to science, it became more and more difficult for people to see how it could be possible to answer the old pre scientific theological and philosophical questions, "what is good and what is evil?" Those questions came to be seen as unanswerable and hence meaningless because what the scientific revolution showed, above all, was that what we call "knowledge" (scientia) is possible when, and only when, it can be framed in the form of hypotheses that can be confirmed or disconfirmed by means of experience, i.e., empirical data and observations.

That entailed, for example, the conclusion that metaphysical knowledge (knowledge of Absolute Reality, or God, as It, He or She exists independently of our perceptual and conceptual apparatus) is unattainable. (Nietzsche called this the "death of God.") But that was not an insuperable problem, because metaphysics was immediately replaced by physics, which had far greater cognitive power to predict, explain and control the phenomena being cognized anyway.

What has been an insuperable problem, up to now, has been the unavailability of any cognitively adequate replacement for ethics. Moral knowledge is unattainable because there is, in principle and by definition, no conceivable moral hypothesis that could possibly be proved or disproved by means of any conceivable type of empirical data, test or experiment. That is true, among other reasons, because moral statements do not take the form of empirically testable hypotheses, or hypothetical imperatives ("If you want X, then you can get it by doing Y" -­ but with no guidance as to whether you should want X in the first place). Moral statements take the form of value judgments and categorical imperatives (i.e., commandments or orders as to what you should do or want). Commandments can never be true or false, so they cannot communicate knowledge. And value judgments are incapable of communicating knowledge about the external world; the only thing they can express are subjective wishes, tastes and preferences which are, from a logical and epistemological point of view, completely non-rational and arbitrary, matters of whim, about which we can only say De gustibus non disputandum est.

Of course, it has always been known that beauty exists in the eye of the beholder. What had not been seen so clearly, until the scientific revolution, was that the same was true of good and evil. The first modern personality, Hamlet, expressed this clearly in 1601 when he said "There is nothing either good or bad but thinking makes it so." I.e., good and evil are words for subjective preferences, sentiments of approval or disapproval, that exist only in the mind of the beholder. They do not exist as objective realities whose validity can be known or tested, proved or disproved. And Hamlet's fate shows how confused, paralyzed, violent and self-destructive people can become when they have recognized that it is impossible to know what one "should" do, but have not yet discovered how to replace that question with one that is answerable.

Thus, it is not only God (and the Devil) that are dead; more importantly, so are Good and Evil, the abstract philosophical concepts of which the former are the concrete mythological and theological incarnations. As Ivan Karamazov put it (speaking for those for whom God is the only credible and legitimate source of moral authority), "without God anything is possible, everything is permitted." But even those who, following Kant or Rawls, would like to place their faith in pure (a priori) reason, and would trust it to take the place of God as the source of moral knowledge, are doomed to disappointment and ignorance; for even Kant made it clear that moral knowledge was unattainable. As he put it, "I must destroy knowledge in order to make room for faith (Glaube, also translatable as "belief")." That is, even the most dedicated champion of pure (a priori) practical reason as the source of moral knowledge had to admit that moral knowledge is unattainable; all he could put in its place was faith. And by the time he wrote those words, the Age of Faith had long since been dead and buried. Indeed, the whole history of modern science was one long demonstration that knowledge was attainable when, and only when, one replaced faith with its opposite, the attitude of universal doubt, and refused to believe any proposition that had not been tested against empirical evidence.

One inescapable consequence that followed from all this was the loss of credibility of the traditional sources of moral authority (God and pure reason). Why did that create such a crisis that most of human history since the 17th century has been a series of attempts to come to terms with it, both in theory and in practice? Because human nature abhors a cognitive vacuum, especially in the sphere of practical reason. For without some way of answering the questions that practical reason asks, concerning how to live and what to do, humans are totally disoriented and without direction, a condition that is intolerable and panic-inducing. Once they have discovered the cognitive inadequacies of the moral way of formulating those questions and answers, as they have to an increasing extent since the scientific revolution of the 17th century, and have not yet discovered how to progress to a more cognitively adequate form of practical reason, many people will regress to a more intellectually primitive and politically reactionary set of questions and answers. In the 20th century these took the form of political totalitarianism, which led to genocide; more recently, they have taken the form of religious fundamentalism, which has increasingly led to apocalyptic terrorism. Given the existence of weapons of mass destruction, it hardly needs to be stressed how much both of these ideologies potentially threaten the survival of our species.

These political/ideological movements have been widely, and correctly, interpreted as rebellions or reactions against modernity (whether modernity is conceived of as Western civilization, Jewish science, modern technology, religious unbelief, freedom to express any opinion, or whatever), though usually without specifying what it is about modernity that threatens our very existence and survival. The deepest threat, I would maintain, is cognitive chaos in the realm of practical reason, and thus nihilism in the realm of morality, anomie in the realm of law, and anarchy in the realm of politics. The paradox is that the political movements that have been most widely interpreted as nihilistic and "evil" ­- Nazi, Stalinist and theocratic totalitarianism and their sequelae, genocide and terrorism ­ in fact originated as desperate (and misguided) attempts to ward off nihilism and what their adherents consider "evil." To them, the greatest evil is modernity, on in other words, the modern scientific mentality, which replaces certainty with doubt, dogmatism with skepticism, authority with evidence, faith with agnosticism, coercion with persuasion, violence with words and ideas, and hierarchy with democracy and equality of opportunity ­ all of which fills them with overwhelming dread and terror, amounting to a kind of existential or moral panic.

In fact, to the totalitarian/fundamentalist mind, modernity not only represents absolute evil; it represents something even worse than that, namely, the total absence and delegitimation of any standards of good and evil whatsoever ­ the total death of good and evil, a state of complete anomie and nihilism. For without knowing what is good and evil, how can one know what to do? And without knowing what to do, how can one live (not only biologically, but even mentally)? How can one maintain any mental, emotional, social, cultural or political coherence and order? As Kenneth Tynan remarked, "Hell is not the place of evil; rather, Hell is the absence of any standards at all." That condition is so intolerable to humans that many will regress to even the most irrational and destructive ideology if they cannot find some more epistemologically powerful cognitive structure with which to replace the old moral way of thinking, once its cognitive inadequacy has been so deeply perceived that its credibility has been irreversibly destroyed.

Cognitive growth occurs by finding better and better answers to existing questions. Cognitive development occurs only when one begins to ask a new and different set of questions. We do this only when we notice that our current questions are meaningless because they are unanswerable, so that they need to be replaced with a different set of questions that can be answered. By this point, in the 21st century, we now realize that it is impossible to answer the moral (and legal and political) questions, "How should we live and what ought we to do?" The only questions that are meaningful, in that they can lead to answers that possess cognitive content or knowledge, are the questions "How can we live? i.e., what biological, psychological and social forces, processes and behavior patterns promote, protect and preserve life, and which ones cause death?" For that question can be answered, by means of empirical investigation as to the causes and prevention of the extinction of species (including our own, as by nuclear holocaust or unrestrained devastation of our natural environment), the extermination of social groups (through epidemics of collective violence, such as war, genocide, poverty, famine, etc.), and the deaths of individuals (by means of homicide, suicide, obesity, alcoholism, etc.). In other words, the only possible replacement for ethics or morality that is progressive rather than regressive is the human sciences ­ human biology, psychology and psychiatry, and the social sciences.

Unfortunately, the modern human sciences, unlike the natural sciences, had not yet been invented when the scientific revolution of the 17th century first showed that moral knowledge was unattainable. And even today, the ability of the human sciences to predict, explain and control the objects of their scrutiny (human behavior) is extremely limited, whether compared with that which the natural sciences possess with respect to their objects of study, or with the degree of cognitive power that the human sciences will need to attain if we are to gain the ability to avert the headlong rush to species-wide self-destruction that we currently seem to be embarked upon. In other words, to paraphrase Winston Churchill's remark about democracy, the human sciences are the worst (the least cognitively adequate) of all possible forms of practical reason ­ except for all the others (such as moralism, fundamentalism and totalitarianism)! What that implies is that nothing is more important for the continued survival of the human species than a stupendously increased effort to make progress in the further development of the human sciences, so as to increase our understanding of the causes of the whole range of our own behaviors, from life-threatening (violent) to life-enhancing.

James Gilligan has been on the faculty of the Department of Psychiatry at the Harvard Medical School since 1966. He is the author of Violence: Reflections on a National Epidemic.

"Are space and time fundamental concepts or are they approximations to other, more subtle, ideas that still await our discovery?"

It is hard to conceive of a universe that does not exist in space and persist through time: space and time seem to be the basic framework of the cosmos. Yet what is space and what is time? Are they "things" or are they merely the language we use for organizing events we witness in the world? Moreover, are they even fundamental? Could it be that space and time conveniently summarize more basic ideas somewhat as temperature summarizes the motion of atomic constituents? Will we one day discover "atoms" of space and time---true, fundamental elements which space and time as we now know them are simply coarse approximations?

Brian Greene is a professor of physics and of mathematics at Columbia University and author of The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for an Ultimate Theory.

"Are we ever going to be humble enough to assume that we are mere animals, like crabs, penguins, and chimpanzees, and not the chosen protégés of this or that God?"

Recent events around the world remind us of historical phenomena observed since the dawn of civilizations: wars, genocides, oppression, conquests, occupations, and, of course, killings in the name of some God. Although the underlying principles are the same, modern killings are more sophisticated, spectacular, and effective than those in the past. In a matter of hours, you can now hijack a plane and crush it against an office building killing thousands, or you can (as it was done more than 50 years ago) drop an atomic bomb over a city killing hundreds of thousands of civilians. You can see all that on TV.

Studying non-human animals, contemporary biology, evolutionary theory, and modern ethology have gathered enough knowledge to respond to questions regarding the nature of aggression, social power, alliance formation, hierarchical domination, and attack-defense behavior. Psychology, anthropology and cognitive science have added important pieces extending this knowledge into human animals. From these studies contemporary science has got some deep understanding about what peace is about. In a nutshell, the moral is that there is no absolute, ideal or ultimate peace in the animal kingdom. Peace turns out to be a fragile local phenomenon that depends on circumstances, population density, biological needs, availability of resources, and so on. If you value peace, the best you can do is to provide conditions for peace, not to "install" peace itself.

So, if we have good scientific knowledge about the nature of peace, how come we don't have peace on earth? Well, because we don't want to accept that we are animals. We prefer to continue believing that we are the protégées of our own created Gods, and that we are, in a transcendental sense, different from a chimpanzee. Peace for humans is taken to be something profound, spiritual and pure, not a bio-social emerging phenomenon. Our created Gods provide the moral values that define what the absolute and ultimate peace is supposed to be, and who is supposed to impose it. There is no surprise then if we see intransigent world and religious leaders calling for holy wars, fighting the Evil in the name of the Good, and justifying in the name of peace, the bombing of civilians, the construction of missile shields, or the occupation of foreign territories.

If we really value peace (but I am not sure this is what some world powers really want!), what we need is to provide sustainable conditions for peace. And for this, it would be much easier to know how to do it, if we assume once for all, that we are indeed animals.

Rafael Núñez is professor of Cognitive Science at the University of California at San Diego, and author of Where Mathematics Comes From (with George Lakoff).

"What is value?"

Oscar Wilde once said that "A fool is someone who knows the price of everything and the value of nothing". Economists have struggled with this question for several centuries and have largely given up - most modern economists tacitly assert that price and value are the same thing, except for possible "externalities" that prevent the market system from functioning correctly. But many of us still believe that the value of a good poem or a comforting word may not be fully reflected in its price, and that value to society and GDP are only weakly correlated.

The question behind this question is whether there is an objective basis for saying that one thing is more valuable than another. In the world of esthetics is inevitably subjective. But perhaps this is not as manifest in other domains. For example, in engineering is it possible to say that one design is inherently better than another? This is closely related to the long standing and much debated question of evolutionary progress. Is there a sense in which we can clearly say that organisms tend to evolve toward better designs, when taken over sufficiently long domains in time and space? When we compare the non-living world of four billion years ago to the rich biosphere of the present, the comparison seems obvious to some of us. But this is hotly contested by others, who point to the lack of a objective criteria for quality of design.

I think that, with functionality as the arbitrator, a mathematical framework for distinguishing good and bad designs may be an achievable goal. This has scientific importants for engineering and economics, and profound implications for philosophy, relgion, and even politics. In the postmodern world objectivity is out of fashion. Perhaps it is time for reality to make a comeback.

J. Doyne Farmer , one of the pioneers of what has come to be called chaos theory, is McKinsey Professor, Sante Fe, Institute, and the co-founder and former co-president of Prediction Company in Santa Fe, New Mexico.

Who am I? What am I?

Perhaps I am this stuff here, i.e., the ordered and chaotic collection of molecules that comprise my body and brain.

But there’s a problem. The specific set of particles that comprise my body and brain are completely different from the atoms and molecules than comprised me only a short while (on the order of weeks) ago. We know that most of our cells are turned over in a matter of weeks. Even those that persist longer (e.g., neurons) nonetheless change their component molecules in a matter of weeks.

So I am a completely different set of stuff than I was a month ago. All that persists is the pattern of organization of that stuff. The pattern changes also, but slowly and in a continuum from my past self. From this perspective I am rather like the pattern that water makes in a stream as it rushes past the rocks in its path. The actual molecules (of water) change every millisecond, but the pattern persists for hours or even years.

So, perhaps we should say I am a pattern of matter and energy that persists in time.

But there is a problem here as well. We will ultimately be able to scan and copy this pattern in a at least sufficient detail to replicate my body and brain to a sufficiently high degree of accuracy such that the copy is indistinguishable from the original (i.e., the copy could pass a “Ray Kurzweil” Turing test). I won’t repeat all the arguments for this here, but I describe this scenario in a number of documents including the essay "The Law of Accelerating Returns".)

The copy, therefore, will share my pattern. One might counter that we may not get every detail correct. But if that is true, then such an attempt would not constitute a proper copy. As time goes on, our ability to create a neural and body copy will increase in resolution and accuracy at the same exponential pace that pertains to all information-based technologies. We ultimately will be able to capture and recreate my pattern of salient neural and physical details to any desired degree of accuracy.

Although the copy shares my pattern, it would be hard to say that the copy is me because I would (or could) still be here. You could even scan and copy me while I was sleeping. If you come to me in the morning and say, “Good news, Ray, we’ve successfully reinstantiated you into a more durable substrate, so we won’t be needing your old body and brain anymore,” I may beg to differ.

If you do the thought experiment, it’s clear that the copy may look and act just like me, but it’s nonetheless not me because I may not even know that he was created. Although he would have all my memories and recall having been me, from the point in time of his creation, Ray 2 would have his own unique experiences and his reality would begin to diverge from mine.

Now let’s pursue this train of thought a bit further and you will see where the dilemma comes in. If we copy me, and then destroy the original, then that’s the end of me because as we concluded above the copy is not me. Since the copy will do a convincing job of impersonating me, no one may know the difference, but it’s nonetheless the end of me. However, this scenario is entirely equivalent to one in which I am replaced gradually. In the case of gradual replacement, there is no simultaneous old me and new me, but at the end of the gradual replacement process, you have the equivalent of the new me, and no old me. So gradual replacement also means the end of me.

However, as I pointed out at the beginning of this question, it is the case that I am in fact being continually replaced. And, by the way, it’s not so gradual, but a rather rapid process. As we concluded, all that persists is my pattern. But the thought experiment above shows that gradual replacement means the end of me even if my pattern is preserved. So am I constantly being replaced by someone else who just seems a like lot me a few moments earlier?

So, again, who am I? It’s the ultimate ontological question. We often refer to this question as the issue of consciousness. I have consciously (no pun intended) phrased the issue entirely in the first person because that is the nature of the issue. It is not a third person question. So my question is not “Who is John Brockman?” although John may ask this question himself.

When people speak of consciousness, they often slip into issues of behavioral and neurological correlates of consciousness (e.g., whether or not an entity can be self-reflective), but these are third person (i.e., objective) issues, and do not represent what David Chalmers calls the “hard question” of consciousness.

The question of whether or not an entity is conscious is only apparent to himself. The difference between neurological correlates of consciousness (e.g., intelligent behavior) and the ontological reality of consciousness is the difference between objective (i.e., third person) and subjective (i.e., first person) reality. For this reason, we are unable to propose an objective consciousness detector that does not have philosophical assumptions built into it.

I do say that we (humans) will come to accept that nonbiological entities are conscious because ultimately they will have all the subtle cues that humans currently possess that we associate with emotional and other subjective experiences. But that’s a political and psychological prediction, not an observation that we will be able to scientifically verify. We do assume that other humans are conscious, but this is an assumption, and not something we can objectively demonstrate.

I will acknowledge that John Brockman did seem conscious to me when he interviewed me, but I should not be too quick to accept this impression. Perhaps I am really living in a simulation, and John was part of the simulation. Or, perhaps it’s only my memories that exist, and the actual experience never took place. Or maybe I am only now experiencing the sensation of recalling apparent memories of having met John, but neither the experience nor the memories really exist. Well, you see the problem.

Ray Kurzweil was the principal developer of the first omni-font optical character recognition, the first print-to-speech reading machine for the blind, the first CCD flat-bed scanner, among other major inventions, and author of The Age of Spiritual Machines.

"Why is life so full of suffering?"

It is a bit embarrassing to admit a preoccupation with this gigantic old question, but it is human, I suppose. Tackling it straight on seems to be an exercise in hubris, but if you stick to science, you soon realize that we are still struggling to figure out what the question is. It helps, I think, to distinguish four separate questions.

The first question is why capacities for suffering exist at all. Why do organisms care if they are injured? Why do they try so hard to avoid dying? Why do they fight just to have sex? Why do we experience a certain kind of pain just from being ignored? Such motives, behaviors, and experiences are made possible by brain mechanisms shaped by natural selection. While many individual experiences of suffering arise because something has gone wrong, either in person's life or brain, the capacities for suffering and pleasure exist because they are useful, at least for the genes that make them possible. This is terribly sobering. Many people still confuse the question of why capacities for suffering exist, with the very different question of what causes suffering in individual instances. I have called this the "clinician's fallacy" because doctors and therapists so often treat defenses as if they were diseases. Eventually the distinction will become clear.

The second question is why we so often continue to do things that make us miserable. Why do we pursue goals we can't reach given that this causes so much unhappiness? Why we can't take Buddha's advice and transcend our desires? The answer is that people who have given up difficult goals have had fewer children. These goals are not just wealth, power and sex. Trying without success to protect and help one's children causes intense suffering and everyone recognizes why we can't give up this goal. The evolutionary origins of our motives do not make us helpless puppets but they can help us to understand why controlling our desires is difficult.

The third question is why we treat others the way we do. It is silly to say that people are innately generous or selfish, but the fact of poverty is universal. I spent this week on call where the truth hits you in the face; for all the riches of our society, millions of people have no job, no money, few friends and not even a warm place to sleep. Politicians enact policies that make it even easier for the rich to keep their riches. This is nothing new, but neither is it unalterable. Any improvement, however, needs to start from the realities of human nature.

The fourth question is very different. The other three ask why people are mostly the same, but this one instead asks why people are different. The explanations for differences in suffering include differences in genes, experiences, personalities, and social settings. Most of our efforts to understand suffering have been here. This research provides genuine knowledge, but only part of a complete answer.

Big problems often motivate proposals for grand quick solutions that give rise to horrendous unanticipated consequences. A gradual deepening of our evolutionary understanding of ourselves offers more modest but surer hope. Many misgivings about evolutionary approaches to human behavior come from a simple misconception. Natural selection explains how the competitive struggles of life shaped us, but this does not mean that life is only a struggle nor does not mean that life cannot be made better. Quite the contrary. If we want to prevent social catastrophes and gradually improve our world, we had better start with a real understanding of why we are the way we are. Negative psychology tells us why some people are unhappy and how bad this is for them. In another corner, positive psychology tells us why some people are happier than others and how good this is for them. What we need now is "diagonal psychology" that investigates the costs of experiencing positive emotions when they are not warranted, and the benefits of capacities for suffering. This will offer a real foundation for understanding why the world is so full of suffering.

Randolph M. Nesse is Professor of Psychiatry and Professor of Psychology at the University of Michigan and editor of Evolution and the Capacity for Commitment.