For decades, physicists have accepted the notion that the universe started with the Big Bang, an explosive event at the literal beginning of time. Now, computational physicist Neil Turok is challenging that model -- and some scientists are taking him seriously.
According to Turok, who teaches at Cambridge University, the Big Bang represents just one stage in an infinitely repeated cycle of universal expansion and contraction. Turok theorizes that neither time nor the universe has a beginning or end.
It's a strange idea, though Turok would say it's no stranger than the standard explanation of the Big Bang: a singular point that defies our laws of physics, where all equations go to infinity and "all the properties we normally use to describe the universe and its contents just fail." That inconsistency led Turok to see if the Big Bang could be explained within the framework of string theory, a controversial and so-far untested explanation of the universe as existing in at least 10 dimensions and being formed from one-dimensional building blocks called strings. Within a school of string theory known as m-theory, Turok said, "the seventh extra dimension of space is the gap between two parallel objects called branes. It's like the gap between two parallel mirrors. We thought, What happens if these two mirrors collide? Maybe that was the Big Bang."
Turok's proposition has drawn condemnation from string theory's many critics and even opposition from the Catholic Church. But it's provoked acclaim and wonder, too: He and Princeton University physicist Paul Steinhardt published Endless Universe: Beyond the Big Bang last year, and Turok -- also the founder of the South Africa-based African Institute for Mathematical Sciences -- won 2008's first annual TED Prize, awarded to the world's most innovative thinkers.
Turok spoke with Wired.com about the Big Bang, the intellectual benefits of cosmology and his bet with Stephen Hawking.
Wired: In a nutshell, what are you proposing?
__Neil Turok: __In our picture, there was a universe before the Big Bang, very much like our universe today: a low density of matter and some stuff called dark energy. If you postulate a universe like this, but the dark energy within is actually unstable, then the decay of this dark energy drives the two branes together. These two branes clash and then, having filled with radiation, separate and expand to form galaxies and stars.
Then the dark energy takes over again. It's the energy of attraction between the two branes: It pulls them back together. You have bang followed by bang followed by bang. You have no beginning of time. It's always been there.
__Wired: __But isn't there still a beginning?
__Turok: __Imagine you have a room full of air, with all these molecules banging around. The vast majority of time, these molecules spread uniformly -- but once in a trillion trillion years, they all end up in the corner of the room. If you look at the room and run the clock forward, they'll eventually make themselves uniform: But it would reverse, and you'd watch them flying into the corner. Then they'd fly out again.
If this is right, it means that time runs forward for a while. Then there's a random state without an arrow of time, then time runs backwards, and then time runs forward again. That's the bigger picture: We're still very far away from understanding it, but that would be my bet.
But my main interest is the problem of the singularity. If we can't understand what happened at the singularity we came out of, then we don't seem to have any understanding of the laws of particle physics. I'd be very happy just to understand the last singularity and leave the other ones to future generations.
__Wired: __How do you test this theory?
__Turok: __If the universe sprung into existence and then expanded exponentially, you get gravitational waves traveling through space-time. These would fill the universe, a pattern of echoes of the inflation itself. In our model, the collision of these two branes doesn't make waves at all. So if we could measure the waves, we could see which theory is right.
Stephen Hawking bet me that we'll see the signal from inflation. I said that we won't, and he can take it for any amount of money at even odds. So far he hasn't named an amount. He's richer than me, so he's being nice.
__Wired: __You've said the standard explanation of the Big Bang is Rube Goldberg-ian, but this seems like quite the convoluted contraption, too.
__Turok: __The structure of the sandwich was forced on theorists by mathematicians: It's basically the only way you can make the equations consistent and avoid infinity. The extent to which we believe it derives from the mathematics. We're not smoking something and making it up.
However, I feel that the main role for these scenarios of the early universe is to stimulate our thinking. I don't necessarily believe any of them. The most important thing is that the only intellectually honest way to study such questions of cosmology is to make the most precise model you can. I think of the whole thing as a giant intellectual exercise, a stimulating exercise, to make us better appreciate the universe.
__Wired: __It's stirred a lot of emotion for an intellectual. When Alan Guth criticized you and your theory at a conference, he showed a picture of a monkey. Is this sort of vitriol normal?
__Turok: __The monkey was maybe a bit exaggerated. But I'm actually good friends with Guth, and I'm sure he did it as a joke. I meet him regularly at conferences, and he's a reasonable guy. The field is driven by reason. The inevitably human things that come into it don't matter in the long run.
In the end, bad ideas will not survive. If you have a good, clean idea that's elegant and precise and agrees with observations, it'll get through.
__Wired: __The Catholic Church hasn't been very receptive to your ideas, either.
__Turok: __I think they like the Big Bang for obvious reasons. It's a creation event, and they find that appealing. Whereas if you talk to most physicists, they'd prefer that there was not a creation event, because there are no laws of physics that indicate how time could begin.
I'm not motivated by [theological considerations]. I'd be perfectly happy with a mathematically precise description of how time began. I see science and religion as being two completely different things. I don't see science as relevant to the question of whether or not there's a God.
If the world is cyclical, in a sense you still need a policeman to enforce the laws of physics. If you need a God to do that, fine -- but I think that's a belief in why the world is the way it is. Science studies how the world operates, not why it's here.
__Wired: __To many people, science is valuable because of the metaphors it gives us -- a poetry of the natural world. Does your work resonate that way with you?
__Turok: __We need poetry as well as science, but it's completely irrelevant to the science. That doesn't motivate me either. I just feel incredibly lucky and honored to think about these problems and try to make models that may or may not be relevant. It's a fantastic privilege to ponder these questions -- even if we don't succeed, even if all we do is appreciate how hard the problem is, it brings us together. The world is an incredible miracle, and we have to do whatever we can to appreciate it.
__Wired: __Whatever you find, though, it's not going to have much everyday importance.
__Turok: __No, but one of the extraordinary things about the field is that whatever culture people come from, they all love this stuff. The popularity Hawking has achieved is due in part to him being an exceptional individual, but it's also because the questions and the science are inherently fascinating.
It's been amazing to see students from all over Africa, from countries that have been disaster areas for 30 years, come to the African Institute for Mathematical Sciences and try to best Einstein.
The side effects are quite good, too. I teach math to hundreds of students every year, and because the stuff we work on is high-powered and rigorous, we add to the intellectual environment. Many of the brightest students love to do this. It's like the Apollo moon program, which had a huge spinoff in technology. So even though this kind of science and thinking has no intrinsic economic value, it's hugely motivating and quite cheap.
__Wired: __With all your work with students from Africa, what do you think of James Watson's remarks on Africans evolving to possess less intelligence than other racial groups?
__Turok: __I think he's nuts. My students are highly motivated and have a very high success rate. If he really believes they're inferior, he should just come to the institute. I guarantee that if he spends an afternoon with these students, he'll revise his opinion.
