What if the Big Bang wasn't the beginning of the universe, but only one stage in an endlessly repeated cycle of universal expansion and contraction?
So suggests mathematical physicist and string theorist Neil Turok. He thinks there may be many universes, at once interpolated but separate, like a mixture of gases. These universes are attracted to each other; every few trillions of trillions of years, they collide, explode, expand and contract, then repeat the sequence all over again.
I recently spoke with Turok, winner of the first TED Prize of 2008, for an upcoming Wired News Q&A. Here are some outtakes from our conversation:
__On the Big Bang's problems: __
*The Big Bang theory rests very strongly on Einstein’s theory of general relativity, which combines with nuclear and particle physics and all the other physical laws to describe the contents of the universe. The theory is that 13.7 billion years ago, there was a singularity, a point of infinite density, and the universe emerged, emerging and very hot, from that singularity. *
But the singularity is not describable with Einstein’s theory. The theory fails: everything goes to infinity. The density of the universe goes to infinity. The curvature of spacetime goes to infinity. All the properties we normally use to describe the universe and its contents just fail.
Experts just say, “Let’s assume the universe sprang into existence, start our decription a tiny fraction of a second after that, run the clock forward and never ask where it came from.”
The origins of Turok's motivations:
*Well, a theory called inflation was invented to deal with the singularity: maybe the singularity was full of a weird type of energy that caused it to expand with exponential speed. My own work started because I was skeptical of this framework. It seemed to me that the inflationary models were adding so many ad-hoc ingredients to solve the problems. I like to have a simple solution, not some kind of Rube
Goldberg machine. *
Then string theory came along, and its successor, m-theory. It’s not fully understood yet, but it seems to anticipate some of the most profound features of the world. From the very simple assumption that all types of matter and all forces in the world can be described in terms of a string, a one-dimensional vibrating object, one is led to types of particles and forces like those we see: electromagnetism, quarks, neutrinos -- and you don’t get all those nasty infinities. And it has other remarkable features: according to string theory, the world doesn’t have three dimensions of space, but at least six more. All the laws of particle physics, all the properties we see, are fixed by the size and shape of these six extra dimensions.
Turok's theory:
Imagine two sheets on a washing line, and they're very close together, very nearly parallel. Those are two-dimensional sheets; ours are three-dimensional. Think of it as two intimately intertwined objects which are nevertheless able to exert force on each other, a pull. The Big Bang is the touching of those two sheets. When they touch, they release that energy.
Interestingly, Turok's theory hasn't always been well-received by Christians, for whom the Big Bang dovetails neatly with their creation myths.
Conversely, New Age types have embraced this scientific picture of a cyclical universe without beginning or end. Turok, for his part, doesn't want any such attention. "I see religion and science as being two completely different things," he said. "Science studies how the world operates, not why it?'s here. I think the world is an incredible miracle, and we have to do whatever we can to appreciate it."
*
Image: Not the Big Bang, but Light Echoes From Red Supergiant Star V838 Monocerotis*
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