Lee Smolin on the Nature and Future of the Universe
What is the future of the future? Will it all end in fire or in ice? And what kinds of events will the penultimate (which is always more interesting and much trickier than the ultimate!) reveal? These questions (as well as others, of course!) are addressed to Lee Smolin by Jill Neimark in this column titled “A Talk On the Nature and Future of the Universe.”
This interview with Lee Smolin kicks off a series of dialogues with physicists and cosmologists about the nature and future of the universe. We’re hoping for a few good fights, some laughter, and new insights. Is the universe particularly suited to life, perhaps even designed with life in mind-or is life a lucky accident of this particular universe? Will the universe die by freezing or burning up, or is that a question we can even reasonably ask? Was there one big bang or infinite bangs? Join us as we eavesdrop on the musings of the most interesting cosmologists of our time.
Lee Smolin is a theoretical physicist, professor at Pennsylvania State University, and a member of the Center for Gravitational Physics and Geometry. His newest book, Three Roads to Quantum Gravity (Basic Books) was published this year. Dubbed “The New Einstein” by Discover magazine, Smolin invented a method by which natural selection might operate on the cosmic scale. He has just joined the Perimeter Institute, a new cosmology think tank based in Waterloo, Canada. Perimeter will house around 40 theoretical physicists working on foundational problems in physics including quantum gravity, string theory, foundations of quantum mechanics, quantum information theory and cosmology.
Q: Why do you think so many physicists are interested in the anthropic principle of the universe right now—the idea that the universe is ideally suited to life?
A: There’s a good reason and two bad reasons. The good reason is that there are puzzles about why the universe is the way it is, and why the initial conditions and choices and laws of physics are very special. And it’s good that people are interested in those puzzles. The anthropic principle promises to answer those puzzles. The two bad reasons are that, one: it doesn’t really answer those puzzles, it just gives people the impression they’ve been answered.
Q: How does it give that false impression?
A: There are different versions, and they do so in different ways. One form assumes there is an intelligent creator who is displaced or hidden. And the other version suggests there are an enormous number of universes, maybe infinite, each created with different initial conditions and different laws and then somewhere in there by probability there is a universe that looks like ours, simply because it’s possible. That’s not an explanation. That’s like explaining biology by saying there is a soup of DNA and every possible combination of DNA came together and one of them caused a living being. That’s not how biology works, and I don’t believe that’s how the universe works either.
Q: What’s the other reason you feel the anthropic principle is flawed?
A: People are still looking for a role for God as creator of universe, and these people were forced to beat a tactical retreat from God as the direct creator of human beings because of Darwin. So they’re happy to believe there’s a big bang which gives a role for a creator. If the big bang is true, the universe was created at a finite time, and that idea allows a return to the kind of mythology in which the universe was created by an intelligent creator.
Q: You’re not a fan of the big bang theory.
A: I personally think the big bang is a crazy idea. What we know is that around 14 billion years ago the universe was much denser and hotter, at least as much as the center of a star. What happened before that? One possibility is that the universe simply expanded from a state of infinitedensity and temperature, however it may also be that the expansion was the result of some event that took place, and therefore the big bang is not the beginning of time.
Q: What about a bunch of bangs?
A: People have proposed that the big bang followed the collapse of a previous universe. Another idea is that the big bang is the result of the collapse of a small region of another universe, which would have led to the formation of a black hole.
Q: Which idea do you prefer?
A: I personally think it’s very unlikely that the big bang was the first moment of time. I’m very interested in the question, therefore, of what was before the big bang.
Q: So there aren’t many universes with different properties?
A: I don’t deeply believe that.
Q: What do you deeply believe?
A: I deeply believe that the world is a network of relationships, I deeply believe in causality, that the past causes the future, the past has already happened and the future has not, I deeply believe that time and causality are real. I believe that there is a universe which exists apart from people’s perceptions of it, but I think that a description of that universe from the stance of outside observer is impossible. Therefore our description has to somehow incorporate all possible views from all possible observers.
Q: How do we do that?
A: There’s been a development in mathematics and theoretical physics which shows us how to do that. In math it’s called topos theory, it’s been applied to physics to give this kind of surrealistic or multi-observer formulation of quantum theory. A few people who are working on that are Chris Isham and Jeremy Butterfield and Fotini Markopoulou.
Q: What do you think of recent work in physics showing that certain properties of the universe may be evolving?
A: Evolving is the wrong word to use. It may be that some things we think of as constants in physics, like the fine structure constant, might be changing slowly on a cosmological time scale. The fine structure constant is a ratio formed out of three things: the electric charge of an electron, Planck’s constant, and the speed of light. Evidence was recently published that was not very strong, but nonetheless was not trivial, showing that the fine structure might be slowly changing.
Q: What would that mean for our concept of the universe?
A: If its true its fantastically important, because in standard physical theory these numbers are fixed. The idea that constants of nature might actually not be constant is an old idea, I believe Dirac proposed it in the 1930s. And this work was preceded by other work by Joao Maguejo and Andy Albrecht proposing that the speed of light might have been much larger at very early times of universe when it was very hot. If that were true, it would account for the same things that the inflation theory of the universe does.
If the speed of light or other fundamental constants can change a lot during the extreme conditions at very early times, it might be that there would be small changes during the present universe. What people have observed is evidence for such small changes. But it’s still the early days. In a few years we’ll know whether it was just an artifact of pushing the experiment to the edge, or whether it’s a real effect.
Q: So there are any constants? Any fixed, platonic properties?
A: I’m very attracted by the idea that there are many fewer than we think, that’s not the same as saying there are none.
Q: Nobel-prize winning physicist Steven Weinberg recently wrote an essay for the New York Review of Books called “The Future of Science, and the Universe.” In it he talks about how eventually the universe will either freeze or burn up. Do you agree?
Q: Some cosmologists are interested in what they call the far future of the universe. I was at conference sponsored by the Templeton organization at the Vatican about that. My sense is that it’s a sort of interesting game but we don’t know enough to play it reliably yet. We don’t know what 95% ofthe universe is made of, we don’t know about dark matter, or the cosmological constant. And the constitution of the dark matter and dark energy strongly effect the far future of universe. As Brian Eno once said: Nothing so dates an era as its conception of the future.
Q: Weinberg also suggests we’ll discover a few fundamental principles, and they will be fragile—such that, were they to shift only a little, they wouldn’t function. Do you agree with that?
A: He means brittle rather than fragile: if it changes a little, it breaks. I think it would be nice if there were a few fundamental principles. Some of us are working on a so-called M theory, where all the versions of string theory are tied together in a single theory. I think that’s a very interesting conjecture, but it’s hard to tell if it’s true or not. A great many people believe in the existence of M theory but very few people are actually working on its ultimate formulation.
Q: Is it too hard?
A: No, but it requires a change of mindset, from thinking in terms of objects moving against fixed backgrounds of space and time, to a relational picture of the universe.
Q: The relational nature of the universe has been your passion for a longtime.
A: Not just my passion. The debate about whether space and time are absolute or relational goes back to the Greeks. Leibniz in particular advocated the relational view. Leibniz and a follower of Newton called Clark debated whether it made sense to ask the question, Would the universe be any different if it were 3 feet to the left? Clark said God perceives in an absolute sense where everything is and the location of everything has absolute meaning with respect to this fixed, absolute space so it does make sense to say the universe is here rather than 3 feet to the left. Leibniz argued that space is nothing but an aspect of relationships between things and nothing in the universe would change if it were 3 feet to the left, so the question itself was nonsensical. General relativity is in fact a realization of the relational view. In quantum gravity we had to adopt the relational point of view in order to get sensible answers out of our theory.
Q: But we don’t experience things that way in real life.
A: Actually we do. We notice where something is with respect to something else.
Q: That’s true, but we think of things as fixed against a fixed background.
A: That’s a habit of thought but it’s incorrect.
Q: Do you experience the world relationally?
A: I’ve been thinking about this stuff for so long it’s just natural for me to think about the world that way.
Q: It kind of shifts your sense of figure and ground, doesn’t it?
A: Precisely. And it’s a very important shifting not just for physics but many areas. Darwinian biology is an example of relational thinking, going from an idea of absolute categories that different biological species represented, to the idea that species are a result of evolution within a network of relationships. You see it in social theory, explicitly in the writings of Harvard legal theorist Roberto Unger. He asks: do you see law as reflecting absolute principles of justice which are true eternally and which come from God or human nature or some completely absolute framework? Or do you see law as the result of an historical process by which different groups with different points of view interact to define the rules of society? You see it in art. The old fashioned idea of perspective is that a painting shows things in relation to some absolute geometry, that things are fixed in space, which then gave way to abstract art, where what’s happening on canvas just has to do with relationships. And look at the use of space in modern dance as opposed to 19th-century ballet.