Life, the universe and everything

Think you know a bit about physics? Listen to Brian Greene and you'll realise you're out of touch, writes Arminta Wallace.

When he laughs he looks like John Cusack; when he's serious there's a hint of David Duchovny. Either way, dressed, when we meet, in cool-dude black from head to toe and with no odd socks in sight, he's more movie star than mathematician. But then, as Prof Brian Greene is quick to point out, appearances are awfully deceptive.

"If you go by what you see you're fooling yourself," he says as we gaze out over breathtaking views of the Thames from a suite of penthouse offices at his publisher's London headquarters. "Everything we see is kind of a facade. It's not false, exactly, but it is a facade."

He's not talking about himself, of course, or about the view. He's talking about the nature of reality. And reality, according to Greene and his colleagues at the cutting edge of theoretical physics, is much, much stranger than . . . well, than even science fiction. Ours is a world where space and time curve, warp and tear. At subatomic level everything around us is subject to the quantum jitters, as tiny fragments of matter constantly dance and fizz in a haze of uncertainty. Out in the vast expanses of space it gets even weirder. Our universe may be just one in a series of parallel universes, or branes. Or it could be a hologram in not three, not even four, but 11 dimensions.

"The insights of modern physics have persuaded me that assessing life through the lens of everyday experience is like gazing at a van Gogh through an empty Coke bottle," writes Greene in his new book, The Fabric Of The Cosmos.

Should us ordinary sods be worrying about these things? Yes, actually. Physics may once have been strictly for geeks, but now cosmology - and Greene's brand in particular, an unproven branch of physics known as string theory - is tackling some very big questions about the origins and nature of the universe.

So what is string theory? "I think it's actually pretty simple to describe. If you take a piece of matter and you keep cutting it into smaller pieces you start to wonder, when can I cut no further? Conventional physics stops at uncuttable little dots - particles - but the idea of string theory is that there's at least one other layer. String theory says that inside every particle is a little filament of energy, a tiny vibrating string."

Put like this it sounds remarkably simple. But then Greene has a knack for communicating the complex concepts of his trade in an accessible way. His book The Elegant Universe was shortlisted for a Pulitzer Prize, won science's equivalent of the Man Booker - the Aventis Prize - and spent six months on the New York Times best-seller list. His three-part TV series The Theory Of Everything, shown on Channel 4 last year, used dazzling graphics and a dance soundtrack.

And The Fabric Of The Cosmos doesn't just look good, from the Rothko painting on the cover to the stunning 3-D diagrams inside, but also reads like a dream, making clever use of analogies from pop culture from The Simpsons through Mulder and Scully to designer sunglasses. The trick, Greene insists with a grin, is to exclude the equations.

"Mathematics is a hurdle for most people. There's a feeling that maths and physics are somehow interwoven and that to understand one you need to understand the other. What my book - and many, many others - do is say, look, there are ideas that anybody can take in once the mathematics are stripped away." Ironically, the concept that Greene admits even he can't get a handle on has to do with his own research topic.

"Most of my work in string theory until the last few years was focused on the 11 extra dimensions and trying to understand what they look like. But the extra dimensions are maybe the hardest thing to visualise. When I do my own research I always try to have a mental picture in mind that goes along with the mathematics. I don't feel that I have a gut understanding of things if I need to go back to the equations all the time. The equations give me confidence, but my pictures make sense."

Greene is messianic in his desire to get the essentials of string theory into the popular domain. For the past half-century or more, however, popular perceptions of physics have been lagging farther and farther behind developments. As he ruefully notes, high-school students in the US are still being taught that atoms work like mini solar systems, with particles circling the centre in an orderly, tidy fashion - a notion that was blown out of the water by Heisenberg and his uncertainty principle in 1926. Why?

"Good question," he says. "The education of most students stops with the physics that we knew in the late 1600s. Sometimes it goes a little further. In most other fields, if your education stopped with what was known in the late 1600s it would not feel satisfying, but somehow in physics it's sort of OK. You learn a bit of Newton, a bit of atoms and that's it."

As a working scientist Greene has contributed several significant pieces to the jigsaw of string theory in a career that began at Harvard, took him on a Rhodes scholarship to Oxford, then to Cornell. Since 1996 he has been teaching maths and physics at Columbia University, in New York. As co-director of Columbia's Institute for Strings, Cosmology and Astroparticle Physics he is leading a research programme that is, literally, taking the world apart. Most notably, he and a colleague concluded that the fabric of space-time - time and space fused in a four-dimensional continuum - can tear.

Holes in space? Scary stuff, isn't it? "Scary? Well, see, I think that's the point," he says. "In general relativity it would be very scary, because if space were to rip there'd be some disastrous physical situation as a result. The amazing thing about string theory is that it actually does away with the catastrophe - so although space rips, the strings repair the rip and calm the catastrophe."

Until proven otherwise, however, string theory is just that: a theory. It has yet to be proved in the laboratory, as the entities involved are too tiny to be detected by even the biggest particle accelerators. There are high hopes for an accelerator that's being built in Switzerland, which will come on stream in 2007, but meanwhile Greene and his team at Columbia have turned their attention to bigger things and are combing the cosmos in search of subtle temperature variations in the microwave background.

"We're trying to use astronomical observations to prove these ideas," he says. "If you scribble something really small on a balloon you can't see it, but if you blow the balloon up your scribble will get stretched out. We hope the same thing will prove true of the universe. After the big bang, the strings in string theory left imprints on the universe, too small to be seen. Through billions of years of the expansion of space we hope that those imprints have been smeared across the sky in a way that we can detect - if we know what to look for."

It's a long shot, he admits. But he's an eternal optimist, at least where string theory is concerned. When it comes to the human race he's not so sure. "The first of those TV programmes began with a scene where I'm trying to teach general relativity to my dog," he says. "The point is, my dog is very smart, but there are things that are fundamentally beyond his ability to comprehend. It's not something negative about the dog.

"Now, we can do more than a dog, but why should we be able to do everything? So far we haven't hit a barrier of knowledge, so there's reason for optimism. But are there truths out there that we don't have the brain power to comprehend, because of the limitations of the organ inside our heads? There's every reason to believe that the answer will be yes."

Back in the real world does Greene, as a physicist, see things differently to the rest of us? "I try," he says. "I try to look at things and imagine what's really going on. I try to imagine the atoms and the particles and the strings and the empty space in the stuff in the world around me. As I'm walking I try to think about time flowing at different rates. Working as a physicist gives you a different perspective, that's for sure. But if you show up late for a meeting you still get chewed out of it."

The Fabric Of The Cosmos: Space, Time And The Texture Of Reality, by Brian Greene, is published by Allen Lane, £25 in UK