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On The Edge

In The Third Culture, I noted that physicists had come to the wrong book. They had little to say about the other scientists, and, vice versa. This may have to do with the fact that the language of physics is mathematics; it may also be that ideas about complexity and evolution have not had the same relevance for cosmology and physics as they have for biology and computer science. Astronomers have studied the spectra of light emitted by distant stars billions of years ago, and have so far found no indication that the laws of physics have changed over this epoch.

Cosmology, which came into its own as a science only about thirty years ago, is concerned in part with pinning down the parameters of the universe: its expansion rate, the amount of its mass, the nature of its "dark matter." Cosmologists today are also speculating on more far-reaching questions, such as how the universe was created and how its structure was determined. While some cosmologists are speculating that the laws of physics might explain the origin of the universe, the origin of the laws themselves is a problem so unfathomable that it is rarely discussed. Might the principles of adaptive complexity be at work? Is there a way in which the universe may have organized itself? Does the "anthropic principle"óthe notion that the existence of intelligent observers like us is in some sense a factor in the universe's existenceóhave any useful part to play in cosmology?

The theoretical physicist Lee Smolin is interested in the problem of quantum gravityóof reconciling quantum theory with Einstein's gravitational theory, the theory of general relativity, to produce a correct picture of spacetime. He also thinks about creating what he calls a theory of the whole universe, which would explain its evolution, and he has invented a method by which natural selection might operate on the cosmic scale.

The cosmologist Sir Martin Rees noted in The Third Culture that "one of the key issues in physics is to reconcile gravity with the quantum principle and the microphysical forces. There are various schools of thought; the Stephen Hawking School, the Roger Penrose School, and a number of others. My view is that we're a long way away from a consensus in that field, but Smolin and Ashtekar have injected important new ideas into that debate."

"Quantum gravity was one of the subjects beyond the fringe, when John Wheeler talked about it in the 1950s. Now it's something where serious approaches are being adopted. But we're still a long way from experimental test. Lee Smolin's most important insight was to suggest a new way of looking at space and time in terms of a lattice structure on a tiny scale. It relates in a way to Wheeler's very farsighted ideas of spacetime foam: the idea that if you look at space and time on a very tiny scale, there are no longer three dimensions of space and one of time but the dimensions all get screwed up in a complicated way.

"The other idea with which Smolin is associated is "natural selection" of universes. He's saying that in some sense the universes that allow complexity and evolution reproduce themselves more efficiently than other universes. The ensemble itself is thus evolving in some complicated way. When stars die, they sometimes form black holes. (This is something which I wear my astrophysical hat to study.) Smolin speculatesóas others, like Alan Guth, have also doneóthat inside a black hole it's possible for a small region to, as it were, sprout into a new universe. We don't see it, but it inflates into some new dimension. Smolin takes that idea on board, but then introduces another conjecture, which is that the laws of nature in the new universe are related to those in the previous universe. This differs from Andrei Linde's idea of a random ensemble, because Smolin supposes that the new universe retains physical laws not too different from its parent universe. What that would mean is that universes big and complex enough to allow stars to form, evolve, and die, and which can therefore produce lots of black holes, would have more progeny, because each black hole can then lead to a new universe; whereas a universe that didn't allow stars and black holes to form would have no progeny. Therefore Smolin claims that the ensemble of universes may evolve not randomly but by some Darwinian selection, in favor of the potentially complex universes."

The physicist Alan Guth points out that "a possible reason that Discover magazine dubbed Lee "The New Einstein" on a recent cover is that his work is motivated by the same goalóto construct a unified theory of physicsóand his approach is to keep Einstein's original theory as the fundamental basis of it. Superstring theory basically puts Einstein's theory in the background. The belief is that Einstein's theory will reemerge as a low-energy limit, but it's not the fundamental ingredient of the theory. The fundamental ingredient of the superstring theory is this microscopic string. In Smolin's formulation, the fundamental ingredient remains the gravitational field, and the goal is to treat it quantum mechanically. What he hopes to do that's different from the failed approachóthe approach that successfully quantizes electromagnetism but fails for gravityó is to exploit the fact that the theory of gravity is fundamentally nonlinear."

"The relativity physicists belong to a small club. It's a club that has yet to convince the majority of the community that the approach they're pursuing is the right one. Certainly Smolin is welcome to come and give seminars, and at major conferences he and his colleagues are invited to speak. The physics community is interested in hearing what they have to say. But the majority looks to the superstring approach to answer essentially the same questions."

The physicist Murray Gell-Mann noted "Smolin? Oh, is he that young guy with those crazy ideas? He may not be wrong!"

The synthetic path to investigating the world is the logical space occupied by Gell-Mann, the biologist Stuart Kauffman, the computer scientist Christopher G. Langton, and the physicist J. Doyne Farmer, and their colleagues in and around Los Alamos and the Santa Fe Institute.

The Santa Fe Institute was founded in 1984 by a group that included Gell-Mann, then at the California Institute of Technology, and the Los Alamos chemist George Cowan. Some say it came into being as a haven for bored physicists. Indeed, the end of the reductionist program in physics may well be an epistemological demise, in which the ultimate question is neither asked nor answered but instead the terms of the inquiry are transformed. This is what is happening in Santa Fe.

Stuart Kauffman is a theoretical biologist who studies the origin of life and the origins of molecular organization. Twenty-five years ago, he developed the Kauffman models, which are random networks exhibiting a kind of self-organization that he terms "order for free." Kauffman is not easy. His models are rigorous, mathematical, and, to many of his colleagues, somewhat difficult to understand. A key to his worldview is the notion that convergent rather than divergent flow plays the deciding role in the evolution of life. With his colleague Christopher G. Langton, he believes that the complex systems best able to adapt are those poised on the border between chaos and disorder.

Kauffman asks a question that goes beyond those asked by other evolutionary theorists: if selection is operating all the time, how do we build a theory that combines self-organization (order for free) and selection? The answer lies in a "new" biology, somewhat similar to that proposed by Brian Goodwin, in which natural selection is married to structuralism.

The evolutionary biologist Stephen Jay Gould noted in The Third Culture that "He's following in the structuralist tradition, which should not be seen as contrary to Darwin but as helpful to Darwin. Structural principles set constraints, and natural selection must work within them. His "order for free" is an outcome of sets of constraints; it shows that a great deal of order can be produced just from the physical attributes of matter and the structural principles of organization. You don't need a special Darwinian argument; that's what he means by "order for free." It's a very good phrase, because a strict Darwinian thinks that all sensible order has to come from natural selection. That's not true."

According to the computer scientist Danny (W. Daniel) Hillis: "Stuart Kauffman is a strange creature, because he's a theoretical biologist, which is almost an oxymoron. In physics, there are the theoretical types and the experimental types, and there's a good understanding of what the relationship is between them. There's a tremendous respect for the theoreticians. In physics, the theory is almost the real stuff, and the experiments are just an approximation to test the theory. If you get something a little bit wrong, then it's probably an experimental error. The theory is the thing of perfection, unless you find an experiment that shows that you need to shift to another theory. When Eddington went off during a solar eclipse to measure the bending of starlight by the sun and thus to test Einstein's general-relativity theory, somebody asked Einstein what he would think if Eddington's measurements failed to support his theory, and Einstein's comment was, "Then I would have felt sorry for the dear Lord. The theory is correct."

"In biology, however, this is reversed. The experimental is on top, and the theory is considered poor stuff Everything in biology is data. The way to acquire respect is to spend hours in the lab, and have your students and postdocs spend hours in the lab, getting data. In some sense, you're not licensed to theorize unless you get the data. And you're allowed to theorize only about your own dataóor at the very least you need to have collected data before you get the right to theorize about other data."

"Stuart is of the rare breed that generates theories without being an experimentalist. He takes the trouble to understand things, such as dynamical-systems theory, and tries to connect those into biology, so he becomes a conduit of ideas that are coming out of physics, from the theorists in physics, into biology."

Kauffman and Smolin began working together a year ago and a result of this collaboration is a paper entitled "A Possible Solution For The Problem Of Time In Quantum Cosmology". An introductory letter from Smolin with initial comments from the theoretical physicist Julian Barbour and Murray Gell-Mann begin the related thread in the Reality Club.

While some of this material, particularly in the paper, is mathematical, most of it is readable by non-scientists. A few weeks ago I received an email from the novelist Bruce Sterling, who wrote: "This is truly a remarkably interesting mailing list; despite its recherche topics it seduces me into reading it almost every time." It is in this spirit I present Stu Kauffman and Lee Smolin's paper, "A Possible Solution For The Problem Of Time In Quantum Cosmology."

- JB

The Paper...