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Space and time, strings attached

The Fabric of the Cosmos: Space, Time, and the Texture of Reality, Brian Greene, Alfred A. Knopf: 574 pp., $28.95

March 07, 2004|K.C. Cole | K.C. Cole is a science writer for The Times and author of "Mind Over Matter: Conversations With the Cosmos" and "The Hole in the Universe: How Scientists Peered Over the Edge of Emptiness and Found Everything."

A few years ago, Brian Greene, a mathematician and physicist at Columbia University, wrote a witty, deep, yet wholly accessible book on the remote subject of string theory, which deservedly became a bestseller and made Greene the closest thing to a rock star in his field. He was even the host of a TV show based on the book, "The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory."

Such a debut is hard to live up to, and Greene's new book, "The Fabric of the Cosmos: Space, Time, and the Texture of Reality," does lack some of the loveliness of his first. The difficulty comes with the territory: This book covers all of space and time -- which includes just about everything in physics and sometimes reads that way. At his best, though, Greene is as elegant as ever, cutting through the fog of complexity with insight and clarity; space and time, you might even say, become putty in his hands.

In the end, Greene confirms our worst fears: Rumors of the doom of space and time have not been exaggerated. They've been unraveling ever since Albert Einstein, and the worst is yet to come. Understanding the "why" requires confronting a question that has blown minds for millenniums: What are space and time, anyway? Begin by leaving your smug notions of "reality" at the door. "It's easy to be seduced by the face nature reveals directly to our senses," writes Greene, who compares everyday reality to a magic act in which nature tricks us with her clever sleights of hand. "In recent years, physicists have expended much effort in trying to explain nature's ruse."

What they've found is enough to turn your insides out. Take space. Is it real? The argument has raged for centuries. Isaac Newton unambiguously asserted that space is "out there" like a chess board on which we play our lives; philosopher Gottfried Wilhelm von Leibniz scoffed, saying space is merely a way to order relationships between objects -- no more real than a family tree. Einstein turned Newton's solid space to taffy, showing that it stretched and shrank depending on the relative motion of observers. Then he warped it, and so explained gravity. But even Einstein wasn't willing to believe the implications of quantum mechanics, which predicted that two particles having no contact whatsoever can somehow be in touch over arbitrarily large swaths of space -- an obvious absurdity. Yet laboratory experiments have since demonstrated that particles do just that. And what is "space" if it doesn't separate one thing from another?

As for time, it too feels intuitively "out there." Newton saw it as a cosmic metronome that orders events: Future follows present follows past. But Einstein showed that two observers can't even agree on which events are simultaneous -- never mind how fast time flows.

"These theories," Greene writes, "showed that we each pick up a shard of Newton's old universal time and carry it with us." Worse, we can't even pass from one moment to the next because all moments are ever-present.

Consider: Someone writes you a letter from New York, saying it's snowing "now." Two days later, you receive the letter. Is it snowing "now"? When is "now," anyway? And where?

You don't have to decide because each moment exists for always somewhere in space-time. "If you were having a great time at the stroke of midnight on New Year's Eve, 1999," Greene writes, "you still are." Wherever you go, it's here. Whenever it is, it's now. This is not your grandfather's clock. Between relativity and quantum mechanics, there's no where to stand; no when to stand, either.

Greene explains much of this through the imaginary adventures of Marge, Bart, Lisa, Homer and a large cast of other characters drawn from popular culture. In "The Elegant Universe," Isaac and Albert, George and Gracie, played similar roles. But many of his "thought experiments" in "The Fabric of the Cosmos" are so overwrought that they become confusing. It's hard to imagine a story starring Scully and Mulder that's harder to follow than an episode of "The X-Files." But here it is.

Soon enough, though, Greene woos us back, explaining ideas in clear, direct, often poetic language. For example, one of the ways our everyday notions of "here" and "now" may emerge from the state of all heres, all nows, is through the act of observation. Once we note something, we pin it down.

The underlying reason is that particles are really probability waves, and waves don't occupy a single time or space. Your observation "breaks" the wave -- bringing about what physicists call the "collapse of the wave function." The description of how all this works (and how it doesn't) is as good as it gets. And yet, Greene writes, "[a]fter more than seven decades, no one understands how or even whether the collapse of a probability wave really happens."

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