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From the Archives: Shattering Time

[The blogger is, amazingly, still in France on an epic vacation that has included a bit of work here and there (some columns yet to run, plus a side trip to Geneva to CERN) and a rental-car adventure to the Loire and Normandy (to be typed up for the Post soon enough). Paris is now empty but for tourists. Making fourth trip to Louvre today, for column breaking the news that it is a humdinger of a museum. Next week this blog will be back up and running in real time. Thanks for your patience. Time is, of course, subjective and not absolute, as you will see in the March 2004 Style section article reprinted below -- headlined "Second Thoughts."]

By J.A.

We're going for a walk with Brian Greene, the physicist, at 5 in the afternoon, but this is a rough approximation, since spacetime has no absolutes, and even the familiar notion of "right now" has no meaning in a strict scientific sense. Also neither one of us has a watch.

We have departed from the canopied entrance of the Topaz Hotel and are moving west, following the sun. In this little slice of spacetime the day is coming to an end. Animate blobs of sentient matter rapidly stride toward their cars and the Metro.

The key thing to know about time, Greene says, is that you alter it simply by going for a walk. We know this from Albert Einstein's special theory of relativity.

"As we walk down the street," Greene says, "you can imagine our time ticking away at a different rate than the fellow standing still over there. As we walk, we shatter time! This is the power that relativity gives us."

In a couple of hours Greene will be standing in front of a bookstore crowd, discussing his new book, "The Fabric of the Cosmos: Space, Time, and the Texture of Reality." He's a 41-year-old professor of physics and mathematics at Columbia University, and perhaps the single best explainer of abstruse science in the world today.

His reputation as a leader in the field of "string theory" must inevitably compete with his reputation as a good-looking guy who's comfortable on television. He recently hosted, with boyish enthusiasm, the three-part PBS series "The Elegant Universe," a madcap romp through the funhouse of modern physics, based on his bestseller by the same name. Invariably Greene is compared to the late Carl Sagan, for like Sagan, Greene makes science sound like the coolest thing humankind ever invented. There's an unspoken refrain of, Check this out, this will really blow your mind . . .

His new book focuses in particular on time, the most baffling dimension of them all. Length, breadth, depth -- no one's got a real problem with those. Time is the brain-boggler.

"I do believe in time," the scientist says. "I just think our intuition about it is wrong."

Just as we hit 18th Street, and seem to be heading into the Starbucks across the street, we take a sharp turn to the right, northward. Or perhaps we also go straight. And left. And stop completely. And return backward. Such multiplicity would be possible under the "many worlds" scenario of quantum mechanics, the hypothesis that there is no singular reality, that not only do subatomic particles exist in probability waves, but all their possible trajectories come true, causing the universe to splinter continually into parallel universes.

Greene finds that theory too extravagant, and in any case, in the version of reality that culminates in this story, we go to the right.

We head up 18th, up Mass. Ave. to Dupont Circle, down 19th. Greene doesn't do much sightseeing -- he's trying to explain that the past is as real as the present.

"I don't think that the past is gone. I think the past feels gone," Greene says. "There you were at a party, New Year's Eve, you were experiencing that moment. I would say you are still experiencing that moment."

Greene isn't just saying that somewhere on some distant place in the universe, an astronomer can see the light finally arriving from some event in our past. That's not controversial. That's simply speed-of-light stuff. When we see the Andromeda galaxy, we're looking about 2 million years into the past, because it takes that long for the light to reach us across the enormous distances of space.

Greene's point is more radical: That there is no such thing as "now." That just as there is no center of the universe, there is no location in the "loaf" of spacetime that's more special than any other. This is an implication of Einstein's theory of relativity (his "special" theory, if you can stand the irony).

"This is really a question of what's real. You're saying what's real to me is 'now' " -- the former judo competitor is hacking at the air in a fashion that might alarm other pedestrians -- "but she" -- a woman walking by -- "would slice through the spacetime continuum at a different angle."

Her very motion alters the way she organizes spacetime. Time passes differently for people in motion relative to one another. Their watches, if initially perfectly synchronized and perfectly constructed to tick at the same pace (this is an imaginary scenario, so never mind the engineering issues), will cease to agree when they move apart. Their version of "now" will no longer match.

It's hard to fathom, but physicists say it's what the equations show, it's incontrovertible, it's just that kind of universe. This time-altering effect is so infinitesimally small that it has no impact on ordinary life, but over cosmic distances the effect can be significant. To Greene, the logical conclusion is that our sense of "now" is a psychological seduction. Sure, you might think that the moment you're in, at this very moment, is the true, correct, unassailable, authentic now, but for gosh sakes you thought the same thing 10 minutes ago and will think the same thing in 10 minutes.

The past is real, the future is real. "The whole thing is real," Greene says on the street corner.

Obviously this is perplexing and a little disturbing. We try to live in the moment. But "the moment" doesn't appear anywhere in the physics equations. Even if we rationally accept the no-now idea as sound science, it's not exactly something you can believe with all your heart. (Maybe later it'll be more persuasive.)

Time and space just haven't been the same since Albert Einstein's "miracle year," 1905, when he cranked out several world-shaking physics papers, among them one called "On the Electrodynamics of Moving Bodies."

Einstein, a clerk in a Swiss patent office, had been conducting thought experiments, trying to imagine, for example, what a beam of light would look like if you were riding on an adjacent beam. In his paper, he made a counterintuitive leap: The speed of light is a constant, regardless of the motion of its source. Light moves the same speed whether you're racing toward it or fleeing from it or looking at it crosswise. You can't speed up a beam of light by running really fast with the flashlight extended.

This postulate led to all manner of bizarre conclusions that have since been borne out experimentally. Suddenly there was no "master clock" of time, no way to establish that two events occurred simultaneously. Einstein's theory required that space and time merge in a way that kept the speed of light constant. Space and time weren't separate things anymore, but rather became a four-dimensional spacetime fabric.

"The world changed when Einstein wrote his papers. And you can't say that too often in the history of science," Greene says.

He grew up on 81st Street in New York City across the street from the planetarium, where he steeped himself in the mysteries of stars and galaxies and a great big universe. He was a math whiz at an early age; public school led to Harvard and then a Rhodes scholarship at Oxford, by which time he had immersed himself in the kind of logic-twisting physics the planetarium would never have dared impose on any young visitor.

The dream of modern physicists like Greene is to find a theory that unifies their ideas into something simple. They desperately want to reconcile Einstein's general theory of relativity, which explains gravity and spacetime on the largest scales, with quantum mechanics, which explains the fuzzy realm of submicroscopic particles. It's embarrassing to need one theory for big things and another for small things. Physicists know their story so far has too many loose ends and contradictions, that their universe is too much of a Rube Goldberg contraption.

Greene in "Fabric" does a heroic job of sorting through the cluttered laboratory of the modern physicist: We learn about inflaton fields, dark energy, spontaneous symmetry breaking, the Higgs ocean, D-branes, p-branes (who you callin' a p-brane?), M-theory, quantum entanglement, the cosmological constant and so on.

Greene has a gift for finding the right metaphor:

"The expansion of the universe slowed down for the first 7 billion years after the initial outward burst, much like a car slowing down as it approaches a highway tollbooth. . . . But the data revealed that, like a driver who hits the gas pedal after gliding through the EZ-Pass lane, the expansion of the universe has been accelerating ever since."

His writing style is conversational. He notes, for example, a long-standing flaw with the standard big-bang theory of the origin of the universe:

"It says nothing at all about time zero itself. And since, according to the big bang theory, the bang is what is supposed to have happened at the beginning, the big bang leaves out the bang. It tells us nothing about what banged, why it banged, how it banged, or, frankly, whether it ever really banged at all."

Physics is the bedrock of science. A physicist always wants to find a more fundamental truth. We know that the world is made of atoms, but what are atoms made of? Sure, protons and neutrons and electrons, but where do they come from? Protons and neutrons are made of three quarks each, but what in tarnation is a quark, exactly, and why do quarks come in different sizes?

Greene and like-minded theorists suspect that quarks are the manifestations of vibrating one-dimensional filaments, called strings. Just as the string on a cello can vibrate to create different notes, so too might Greene's little strings vibrate in ways that create what appears to be different types of particles. It's an appropriate theory for a man whose father composed off-Broadway musicals.

They're excruciatingly small, these strings.

"A string is to an atom," Greene says, "as a tree is to the universe."

We're at the corner of M and 18th. Solar radiation filtered by the atmosphere is turning the office buildings orange. Greene focuses on the objects at curbside.

"You look at the garbage, you look at the fire hydrant, you see it's made of atoms, and the atoms are made of strings. All of a sudden, the fire hydrant has a kind of beauty to it."

A stubby beauty, but yes.

We go down Connecticut, across Lafayette Square, past the construction on Pennsylvania Avenue. The 19th-century townhouses nudge up against the taller, modern office buildings as though an architect wanted to illustrate different slices of spacetime.

"The single most shocking element of string theory is its requirement that the world have more than three spatial dimensions," Greene says as we cross H street, back toward the Topaz.

There may be 10 spatial dimensions all told, plus the 11th dimension we call time. For years, string theorists assumed the extra dimensions were curled up so tightly they had no size to speak of, but Greene isn't so sure.

"The extra dimensions" -- cue the eerie music -- "may not be so small."

So why don't we see them?

"Because of the way we see."

Our eyes and everything else may be made of strings that are attached, at either end, to what physicists call a brane, a three-dimensional brane in the case of this particular universe. Branes are something that popped out of the string theory equations: No one knows if they really exist or what they're made of (strings?), but the basic notion is that we might be essentially trapped in a 3-D brane (yes, branes make the brain hurt), and unable to perceive the extra dimensions all around us. Only gravity can go brane-hopping. If you could make paper and ink out of gravity, you might conceivably slip a message to the other side. (New school excuse: "The extra dimensions ate my homework.")

"So many people are searching for a deeper level of reality," Greene says. "We've already come up with a deeper reality, one that goes far beyond experience. I just think that makes the world so much more rich, so much more grand. I think it's just exciting."

We're at the bar of the Topaz. (Notice how we suddenly just appeared here. Journalistic wormhole!) It's a blue bar where women order blue drinks. This is what a bar would look like if you could go back to the 1950s and make a movie about life in the year 2004 and persuade the costume designer that people wouldn't wear blinking helmets and gleaming suits with shoulders jutting out like Cadillac fins.

We talk about his life goals.

"I hope to figure out what the underlying structure of space and time is," he says, and it is a mark of his genial nature that this comes out sounding modest. It's not like he wants to be president.

Maybe string theory will be akin to Newton's law of gravity and Einstein's theory of relativity, something that forever alters the world as we know it. But for the moment it is a mathematical triumph that has no proof. There are no observational data that specifically support string theory. This is a mathematically based universe -- and it's a great mystery why -- but that doesn't mean that every brilliant equation corresponds to something that actually exists.

The stakes are high, and it's a competitive business: A rival theory says the fundamental unit of reality is a loop. String theorists might be barking up the wrong tree.

"It could all be wrong," Greene says.

Could be a total waste of spacetime.

It's a little after 6:30, and Brian Greene heads off to the bookstore, a man on a mission, with a book to promote and a reality to figure out. It's been an interesting conversation, one that will always be real, and always, in its own special way, right now.

By Joel Achenbach  |  August 2, 2006; 5:53 AM ET
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