The Exquisite Role of Dark Matter

Priyamvada Natarajan [6.10.15]

It is definitely the golden age in cosmology because of this unique confluence of ideas and instruments. We live in a very peculiar universe—one that is dominated by dark matter and dark energy—the true nature of both of these remains elusive. Dark matter does not emit radiation in any wavelength and its presence is inferred by its gravitational influence on the motions of stars and gas in its vicinity. Dark Energy, discovered in 1998, meanwhile is believed to be powering the accelerated expansion of the universe. Despite not knowing what the dark matter particle is or what dark energy really is, we still have a very successful theory of how galaxies form and evolve in a universe with these mysterious and invisible dominant components. Technology has made possible the testing of our cosmological theories at a level that was unprecedented before. All of these experiments have delivered very exciting results, even if they're null results. For example, the LHC, with the discovery of the Higgs, has given us a lot more comfort in the standard model. The Planck and WMAP satellites probing the leftover hiss from the Big Bang—the cosmic microwave background radiation—have shown us that our theoretical understanding of how the early fluctuations in the universe grew and formed the late universe that we see is pretty secure. Our current theory, despite the embarrassing gap of not knowing the true nature of dark matter or dark energy, has been tested to a pretty high degree of precision.                      

It's also consequential that the dark matter direct detection experiments have not found anything. That's interesting too, because that's telling us that all these experiments are reaching the limits of their sensitivity, what they were planned for, and they're still not finding anything. This suggests paradoxically that while the overall theory might be consistent with observational data, something is still fundamentally off and possibly awry in our understanding. The challenge in the next decade is to figure out which old pieces don't fit. Is there a pattern that emerges that would tell us, is it a fundamentally new theory of gravity that's needed, or is it a complete rethink of some aspects of particle physics that are needed? Those are the big open questions.

PRIYAMVADA NATARAJAN is a professor in the Departments of Astronomy and Physics at Yale University, whose research is focused on exotica in the universe—dark matter, dark energy, and black holes. Priyamvada Natarajan's Edge Bio Page


I'm a theoretical astrophysicist, working on what I think are some of the most exciting, open and challenging questions. The first is trying to understand the nature of dark matter, and the second question pertains to the physics of black holes. Part of my interest in these two questions, aside from the fact that we now have an enormous amount of data that can help us understand these very enigmatic objects in the universe, is that we have a standard theory—a theoretical model—that works extremely well.

This is a model of structure formation in which dark matter, which is the dominant matter component in the universe, is in the driving seat. It's the scaffolding in which all the first galaxies form, the first stars form, and so on. While we have this exquisite inventory and role for dark matter, we do not know what it is, what it's composed of, what kind of particle it is, when it was created in the universe, and so on and so forth. Similarly, with black holes; we know that they exist. They are real. There is one in the center of our galaxy, which is a few million times the mass of the sun. The one in the center of our galaxy is a dormant black hole. It's not doing very much at present, it was likely active in the past. We see in the early universe that there are massive black holes that are 1000 times, 10,000 times more massive than the one in the center of the galaxy that play a very important role in shaping the properties of the galaxy which hosts them.

What is the life-story of a black hole? How do they grow? How do they form, evolve, and then end up as dead black holes? This is an open question because we know that black holes feed on gas, but what we don't understand is precisely how the gas makes it onto this peculiar surface that all black holes have called the "event horizon." The physics, the astrophysics, if you will, or the details of the flow, are very poorly understood. Once again, these are both problems where we have a good, in fact, a rather specialized, detailed broad-brush understanding; however, the very nature of these objects remains unknown. The situation is very similar to that of dark matter that appears to be ubiquitous.

Layers Of Reality

Sean Carroll [5.28.15]

We know there's a law of nature, the second law of thermodynamics, that says that disorderliness grows with time. Is there another law of nature that governs the complexity of what happens? That talks about multiple layers of the structures and how they interact with each other? Embarrassingly enough, we don't even know how to define this problem yet. We don't know the right quantitative description for complexity. This is very early days. This is Copernicus, not even Kepler, much less Galileo or Newton. This is guessing at the ways to think about these problems.

SEAN CARROLL is a research professor at Caltech and the author of The Particle at the End of the Universe, which won the 2013 Royal Society Winton Prize, and From Eternity to Here: The Quest for the Ultimate Theory of Time. He has recently been awarded a Guggenheim Fellowship, the Gemant Award from the American Institute of Physics, and the Emperor Has No Clothes Award from the Freedom From Religion Foundation. Sean Carroll's Edge Bio Page


I've always studied the laws of physics. I've always been curious about how the universe works, where it comes from, what are the rules that govern the behavior of the universe at the deepest level, so I do physics for a living. I study cosmology and the Big Bang and what happened before the Big Bang, if anything. It's a system of things that hooks up in very complicated ways to our human scale lives. There's the natural world that scientists study, and we human beings are part of the natural world.

We Need A Modern Origin Story: A Big History

David Christian [5.21.15]

In modern science, and I include the humanities here, science in a German sense of science—rigorous scholarship across all domains—in modern science we've gotten used to the idea that science doesn't offer meaning in the way that institutional religions did in the past. I'm increasingly thinking that this idea that modernity puts us in a world without meaning—philosophers have banged on about this for a century-and-a-half—may be completely wrong. We may be living in an intellectual building site, where a new story is being constructed. It's vastly more powerful than the previous stories because it's the first one that is global. It's not anchored in a particular culture or a particular society. This is an origin story that works for humans in Beijing as well as in Buenos Aires. 

It's a global origin story, and it sums over vastly more information than any early origin story. This is very, very powerful stuff. It's full of meaning. We're now at the point where, across so many domains, the amount of information, of good, rigorous ideas, is so rich that we can tease out that story. 

DAVID CHRISTIAN is Professor of History, Macquarie University, Sydney; Author, Maps of Time: An Introduction to Big History. David Christian's Edge Bio Page


I'm a Russian historian, and I love teaching Russian history. I taught it during the Cold War when it seemed exceptionally significant. Teaching it in Australia, where I was, was a bit like talking about the dark side. I felt my students needed to know about that world.

I'm not Russian, but I was teaching Russian history and eventually I realized I was giving the subliminal message that humans are divided, at a fundamental level, into competing tribes. Having lived through the Cuban Missile Crisis, I remember it vividly. I was a schoolboy in England where this tribalism threatened to blow us all up. That was a very vivid experience for me. I thought, for historians to keep teaching this subliminal message—that we're divided by tribes—is not a good thing. 

Why some scientific ideas must die

John Brockman [4.29.15]

JB: It all started with a young scientist named Laurie Santos at a conference that I ran saying, “How do we get rid of some of these ideas that are just standing in front of us? Just blocking everybody?”

LP: What are the ideas that blind us now do you think? And blind us into confusion, and argument, and that kind of controversy?

JB: Name a field. ... It comes down to: is science advertising or is it argument?

LP: Your favorite. Which would be one of yours?

JB: Daniel Kahneman has studied human rationality and found out that characteristics we thought we had as humans aren’t necessarily the case. We are not Homo Economicus, we’re not the rational human beings we thought we were. A lot of what we do is pre-conscious and without acknowledgement.

LP: Now that’s interesting. So that’s a big idea about who we are and how we control our lives with rationality and free will. Another idea was the idea of love as well. This is one that attracts criticism from one of your contributors. So tell us a bit more about that. ...

Existential Risk

Jaan Tallinn [4.16.15]
Introduction by

The reasons why I'm engaged in trying to lower the existential risks has to do with the fact that I'm a convinced consequentialist. We have to take responsibility for modeling the consequences of our actions, and then pick the actions that yield the best outcomes. Moreover, when you start thinking about—in the pallet of actions that you have—what are the things that you should pay special attention to, one argument that can be made is that you should pay attention to areas where you expect your marginal impact to be the highest. There are clearly very important issues about inequality in the world, or global warming, but I couldn't make a significant difference in these areas. 

JAAN TALLINN is a co-founder of The Centre for the Study of Existential Risk at University of Cambridge, UK as well as The Future of Life Institute in Cambridge, MA. He is also a founding engineer of Kazaa and Skype. Jaan Tallinn's Edge Bio Page

by Max Tegmark

I find Jaan Tallinn remarkable in more ways than one. His rags-to-riches entrepreneur story is inspiring in its own right, starting behind the Iron Curtain and ending up connecting the world with Skype. How many times have you skyped? How many people do you know who created a new verb?

Most successful entrepreneurs I know went on to become serial entrepreneurs. In contrast, Jaan chose a different path: he asked himself how he could leverage his success to do as much good as possible in the world, developed a plan, and dedicated his life to it. His ambition makes even the goals of Skype seem modest: reduce existential risk, i.e., the risk that we humans do something as stupid as go extinct due to poor planning. 

Already after a few short years, Jaan’s impact is remarkable. He is a key supporter of a global network of non-profit existential risk organizations including The Future of Humanity Institute, The Machine Intelligence Research Institute, The Global Catastrophic Risk Institute, The Centre for the Study of Existential Risk at University of Cambridge, and The Future of Life Institute, the last two of which he co-founded.

I’ve had the pleasure to work with him on The Future of Life Institute from day one, and if you’ve heard of our recent conference, open letter and well-funded research program on keeping artificial intelligence beneficial, then I’d like to make clear that none of this would have happened if it weren’t for Jaan’s support. If you’re an intelligent life form reading this text millions of years from now and marvel at how life is flourishing, you may owe your existence to Jaan.

MAX TEGMARK is a Physicist, MIT; Researcher, Precision Cosmology; Founder, Future of Life Institute; Author, Our Mathematical Universe. Max Tegmark's Edge Bio Page


I split my activity between various organizations. I don't have one big umbrella organization that I represent. I use various commercial organizations and investment companies such as Metaplanet Holdings, which is my primary investment vehicle,to invest in various startups, including artificial intelligence companies. Then I have one nonprofit foundation called Solenum Foundation that I use to support various so-called existential risk organizations around the world.


Anne Wojcicki  &  Jean Pigozzi

"To accomplish the extraordinary, you must seek extraordinary people."

A new generation of artists, writing genomes as fluently as Blake and Byron wrote verses, might create an abundance of new flowers and fruit and trees and birds to enrich the ecology of our planet. Most of these artists would be amateurs, but they would be in close touch with science, like the poets of the earlier Age of Wonder. The new Age of Wonder might bring together wealthy entrepreneurs ... and a worldwide community of gardeners and farmers and breeders, working together to make the planet beautiful as well as fertile, hospitable to hummingbirds as well as to humans. —Freeman Dyson

In his 2009 talk at the Bristol Festival of Ideas, Freeman Dyson pointed out that we are entering a new Age of Wonder, which is dominated by computational biology.  The leaders of the new Age of Wonder, Dyson noted, include "biology wizards" Kary Mullis, Craig Venter, medical engineer Dean Kamen, and "computer wizards" Larry PageSergey Brin, and Charles Simonyi, and  John Brockman and Katinka Matson, the cofounders of Edge, the nexus of this intellectual activity. 

Every year since 1999, we have hosted The Edge Annual Dinner (sometimes referred to as “The Billionaires' Dinner”). Guests have included the leading third culture intellectuals of our time, dining and conversing with the founders of Amazon, AOL, eBay, Facebook, Google, Microsoft, PayPal, Space X, Skype, and Twitter. It is a remarkable gathering of outstanding minds—the people who are rewriting our global culture. 

Paul AllenJulia Milner, Yuri Milner

Through such gatherings, its online publications, master classes, and seminars, Edge, operating under the umbrella of the non-profit  501 (c) (3) Edge Foundation, Inc., promotes interactions between the third culture intellectuals and technology pioneers of the post-industrial, digital age, the "worldwide community of gardeners and farmers and breeders" referred to by Dyson as the leaders of the "Age of Wonder”. Edge members share the boundaries of their knowledge and experience with each other and respond to challenges, comments, criticisms, and insights. The constant shifting of metaphors, the intensity with which we advance our ideas to each other—this is what intellectuals do. Edge draws attention to the larger context of intellectual life.

An indication of Edge's role in contemporary culture can be measured, in part, by its Google PageRank of "8", which places it in the same category as The Economist, Financial Times, Le Monde, La Repubblica, ScienceSüddeutsche Zeitung, Wall Street Journal, and Washington Post. Its influence is evident from the attention paid by the global media:

 "The world's smartest website … a salon for the world's finest minds." Guardian—"the fabulous Edge symposium" New York Times—"A lavish cerebral feast", Atlantic—"Not just wonderful, but plausible", Wall St. Journal "Fabulous", Independent—" Thrilling", FAZ—"The brightest minds", Vanity Fair, "The intellectual elite", Guardian—"Intellectual skyrockets of stunning brilliance", Arts & Letter Daily—"Terrific, thought provoking", Guardian— "An intellectual treasure trove, San Francisco Chronicle—"Thrilling colloquium", Telegraph—"Fantastically stimulating", BBC Radio 4—"Astounding reading", Boston Globe—"Where the age of biology began", Süddeutsche Zeitung—"Splendidly enlightened", Independent—The world’s best brains", Times— "Brilliant... a eureka moment at the edge of knowledge", Sunday Times—"Fascinating and provocative", Guardian—"Uplifting ...enthralling", Daily Mail—"Breathtaking in scope", New Scientist—"Exhilarating, hilarious, and chilling", Evening Standard—"Today's visions of science tomorrow", New York Times

Larry Page & Jesse Dylan

Edge is different from The Invisible College (1646), The Club (1764), The Cambridge Apostles (1820), The Bloomsbury Group (1905), or The Algonquin Roundtable (1919), but it offers the same quality of intellectual adventure.

Perhaps the closest resemblance is to the early nineteenth century Lunar Society of Birmingham (1765), an informal dinner club and learned society of leading cultural figures of the new industrial age—James Watt, Joseph Priestly, Benjamin Franklin, and the two grandfathers of Charles Darwin, Erasmus Darwin and Josiah Wedgwood. The Society met each month near the full moon. They referred to themselves as "lunaticks". In a similar fashion, Edge attempts to inspire conversations exploring the themes of the post-industrial age. 

Tim O'Reilly Marissa Mayer

In this regard, Edge is not just a group of people. I see it as the constant shifting of metaphors, the advancement of ideas, the agreement on, and the invention of, reality.

John Brockman 
 Vancouver, March 18, 2015

Subscribe to Front page feed