Music of the Spheres

Consider the well-orchestrated physics behind your favorite symphony. Each instrument produces a specific set of harmonics, determined by its three-dimensional form: the buxom bulges of the violin, the brassy coils of the horn, the straight-laced flute, the angel wing-shaped harp, the pancake-flat cymbals. All together, they can produce an elegant piece of artistry. And if a rapidly growing chorus of physicists is right, the universe is created in much the same way. Everything in it--from gravity to grapevines--is the direct result of resonances sent forth from the bulges and curls and holes in the geometry of six unseen dimensions. Tiny beyond belief, these multidimensional vibrating strings and membranes produce the whole of the cosmos--six-dimensional flutes and horns and violins singing out the whole shebang.

A pretty idea, you might think, but rather hard to take seriously as real science. Until just a few years ago, most of the physics community would have agreed. But since a seminal meeting at USC in 1995, a series of breakthroughs has made the theory--known as “string theory”--impossible to ignore.

The six unseen dimensions have grown to 7, and the most recent version is known as “M Theory”--M as in Magic, Mystery, Membrane, Mother, Matrix, depending on whom you talk to. Some physicists prefer to call it “U Theory” because so much is unknown. By any name, it’s highly ethereal stuff, hard to imagine much less understand. But thanks to Brian Greene, a mathematician and physicist at Columbia University, there’s hope. As one of the architects of string theory, Greene has a prime vantage point from which to tell the story. He’s also an enormously gifted teacher, one who provides the guide rails a reader needs to explore such potentially treacherous territory. Climbing sometimes in baby steps, sometimes in great leaps, he offers plenty of breathtaking overviews, rest stops and refreshment in the form of stories of the history and people who built this bizarre--admittedly still under-construction--edifice.

“The Elegant Universe” is an ambitious, patient and frequently personal attempt to bring both the beauty and substance of string theory down to Earth for the general public. And it couldn’t come at a better time. For all the people who’ve been hoping to avoid dealing with a daunting subject, it’s time to wake up and smell the 11-dimensional coffee: Even if string theory turns out to be wrong, the ideas it’s spun forth thus far are sure to be woven into the ongoing revolution in physics.

String theory surfaced in the late 1960s as a way to understand how subatomic particles called quarks stick together inside the atomic nucleus. Few physicists paid attention, however. For one thing, the theory worked only in 26 dimensions. For another, it produced particles faster than light--which is impossible. Eventually, physicists found a better way to understand the glue that holds quarks together, and string theory all but disappeared from the scene.

However, a few faithful followers, led largely by Caltech’s John Schwarz, were too entranced by the mathematical beauty of the theory to let it go. They reduced the 26 dimensions to 10, eliminated the faster-than-light particles and discovered that strings explained a lot more than quarks; they also appeared to produce gravity.

Recently, string theory even found a direct link between elementary particles and black holes--causing even its harshest critics to take a second look.

Needless to say, entering the world of strings requires careful preparation, and Greene makes it as rewarding as it gets. He doesn’t even introduce extra dimensions until late in the game, concentrating instead on the radical revision of space and time brought to us courtesy of Albert Einstein and quantum mechanics.

This is all old stuff, but Greene makes it worth reading again--in part because he writes as if he’s just learned some of this stuff for the first time. When explaining the time dilation that causes subatomic particles to “live longer” when traveling close to light speed, he all but exults: “This really happens!”

Physics requires something like string theory to deal with perhaps its most profound puzzle: The tiny world of the atom, with its fidgety quantum mechanical jumping around, simply does not mesh with the grand world of the cosmos, with its rolling landscape of Einstein’s curving space-time. When joined in equations, the two produce absurd solutions in the form of infinities. “Like a sharp rap on the wrist from an old-time school-teacher,” Greene writes, “an infinite answer is nature’s way of telling us that we are doing something that is quite wrong.”

String theory, so far, is the first successful attempt to tame the infinities in a happy, if complex, marriage of the large and small. If it works, the whole of the universe would be united under one set of laws--a major physical and philosophical milestone. “If string theory is right,” writes Greene, “the microscopic fabric of our universe is a richly intertwined multidimensional labyrinth within which the strings of the universe endlessly twist and vibrate, rhythmically beating out the laws of the cosmos.”

Of course, string theory also requires shedding just about every common-sense notion of space and time held by lay people and physicists alike. Like Alice, we need to feel at ease with believing at least six impossible things. Greene makes this easy in part by commiserating with our discomfort. If you feel a little lost, he seems to say, It’s OK. Everyone does. “What are we to make of this?” he asks. “Does it mean that . . . the universe operates in ways so obscure and unfamiliar that the human mind . . . is unable to fully grasp ‘What really goes on?’ . . . No one knows.”

In bringing the reader so intimately into the journey, Greene addresses those questions you really want to ask but were afraid they’d seem too elementary for serious attention. Why, for example, are there seven hidden dimensions and not more or fewer? Why are they curled up rather than laid out flat, like our the familiar dimensions of depth, width and breadth. What are the “strings” in string theory made of? If string theory provides such a simple, beautiful solution, why didn’t someone think of it before?

The most difficult sections explain Greene’s own contributions to string theory. One, for example, has to do with gluing together bits of six-dimensional balls of compact dimensions, tearing holes in space-time to reshape it from one geometry to another--making a violin out of a flute, so to speak. Greene is, after all, a mathematician.

Luckily, the load is lightened by the many personal insights into how the work of a string theorist actually gets done. On one occasion, Greene was within shouting distance of a crucial result but needed the help of a colleague who never--no exceptions--worked on weekends. It was, of course, Friday night. After bribing the colleague with the promise of a six-pack of beer, he appeared Saturday morning, and they ran their computer program. The result was obviously wrong. Then it turned out they’d made a simple mistake in multiplication that threw the whole calculation off. It’s a consoling thought: Even great minds make mistakes, and even physicists sometimes have to bribe colleagues with beer.

As “The Elegant Universe” shows, the entire history of string theory, in fact, makes a compelling human saga: Discovered only to be discarded, time and time again, resurrected repeatedly--like an off-again, on-again love affair that against everyone’s expectations turned out (maybe) to be the real thing.

So is the universe a symphony played by strings? Only time and space (and experiments) will tell. In the meantime, “The Elegant Universe” offers a thrilling ride through a lovely landscape that will undoubtedly play some important role in whatever canvas the physicists eventually unfold.