The Riddle of Time

By MICHAEL D. LEMONICK

Sometimes it flies, sometimes it crawls, but it always passes inexorably. We mark it, save it, waste it, bide it, race against it. We measure it incessantly, with a passion for precision that borders on the obsessive. Time is so vitally enmeshed with the fabric of our existence, in fact, that it's hard even to conceive of it as an independent entity--and when we try, the result is less than enlightening. Pondering the mystery of what time really is, St. Augustine wrote in his Confessions, "If no one asks me, I know; but if any person should require me to tell him, I cannot."

Indeed, while scientists have harnessed the power of the atom, cracked the genetic code and probed the very edges of the universe, they still don't understand time much better than St. Augustine did. Yet now, as the last few days of the second millennium tick rapidly away (though diehard purists still insist it doesn't really end for another year), we seem more fascinated with the subject than ever. At the Royal Observatory at Greenwich, England, crowds are flocking to a new exhibition, "The Story of Time," which examines time from cultural, religious, artistic and scientific viewpoints. On this side of the Atlantic, the Smithsonian's National Museum of American History has opened a permanent show on America's fascination with time. In bookstores, best-selling author James Gleick's Faster (Pantheon), which laments the accelerating pace of our lives, will be joined next month by The End of Time (Oxford University Press), British physicist Julian Barbour's treatise on the idea that time doesn't even exist. It's nothing more, he says, than an illusion, a sort of cosmic parlor trick.

If so, it's an illusion that has appeared in very different guises to different groups. Says Greenwich observatory director Kristen Lippencott, who put together the British exhibition: "Time is not the thing on our wrists. Time is a cultural object." For many outside the Western European tradition, for instance, time is a circle that turns on a daily, yearly and even a cosmic scale. The Hindu concept of reincarnation is perhaps the most familiar example, but the Hopi in the American Southwest and the Inuit in the Arctic also look at the world as a series of repeating cycles with no beginning or end; so, traditionally, did the Chinese and Japanese cultures.

In the Judeo-Christian West, however, time is a line, marching steadily from the past to the future. As Lippencott puts it, "God never moves backward." Deward Walker, an anthropologist at the University of Colorado, Boulder, argues that this way of viewing time is "part of the reason we have such an advanced science, technology and economy, such mastery of nature and dominance of the universe."

Technology, in turn, has led to our obsession with ultraprecise timekeeping and time management. Before the Industrial Revolution, the exact time of day or year mattered only to those in specialized jobs, such as astrologers and sailors. For the rest, the day began at dawn, noon was when the sun was highest in the sky, and sunset wrapped things up. Says Carleen Stephens, who curated the Smithsonian show, in 1790 fewer than 10% of Americans had a clock of any kind in their homes, and most of those had no minute hand.

Then came trains and factories, and with them the need to coordinate the schedules of hundreds and even thousands of people. It was the railroad companies that invented time zones, in 1883. Because of the earth's rotation, the sun was highest at different times in New York City and, say, Washington, which lay a bit farther west. The 11-min. difference in local noon could lead to disaster at intersections.

Factories, meanwhile, required workers to begin their days together: it's no coincidence that inexpensive alarm clocks and wristwatches began appearing at the end of the 1800s. "In the 19th century," says historian Michael O'Malley, author of Keeping Watch: A History of American Time, "we were urged to merge our sense of time with mechanical devices. It allowed for new forms of social organization."

It also led to a vicious cycle. Once factory owners realized that time was money--a notion that led to the first so-called efficiency experts in the 1920s--the idea of making every second count began to spread through society. Result: efficiency became an American virtue. Today every conceivable business is open around the clock; we multitask frantically, applying makeup or talking on the phone while driving; we cram our kids' lives with team sports and lessons. Children don't play anymore: they schedule play dates. "We are," says author Gleick, "driven by time."

Technology continues to make things worse. Before digital clocks and watches became common, people rounded to the nearest five minutes when telling each other the time: now we give the exact minute. Before cell phones and faxes and answering machines, we accepted being out of touch. Before the Internet, we didn't feel entitled (much less obliged) to shop or do research or work around the clock.

Technology also demands that time be measured ever more precisely. An accurate mechanical clock proved to be so valuable to the British maritime industry in the eighteenth century that the government awarded a hefty prize to its inventor, Joseph Harrison (a story elegantly told in Dava Sobel's 1995 best seller Longitude).

But such a timepiece would be virtually useless today: computers, communications satellites, global-positioning receivers and telephone-switching systems need a precision beyond anything conceivable even 50 years ago. Time technology long since abandoned mechanical devices and even the hum of quartz crystals. For true precision--accuracy to a billionth of a second--you need to travel, virtually at least, to a place like the perfectly circular, well-guarded park that sits in northwest Washington. There, on the grounds of the U.S. Naval Observatory, a nondescript concrete building houses the nerve center of the U.S. Directorate of Time.

Behind its barred windows sit 28 atomic clocks, four of them holding atoms of hydrogen and the rest cesium. When excited by lasers or irradiated with microwaves, the atoms begin to dance with an utterly regular vibration that's monitored by computer. Once each second, the results are fed into America's Master Clock; the measurements from this and similar clocks around the world are sent to the International Bureau of Weights and Measures outside Paris--the ultimate timekeeping authority. It is there, next Friday, that the pulsing of billions of atoms will officially signal that civilization's odometer has turned over from 1999 to 2000.

Yet even the most accurate clock in the world can't answer the question of what all these atoms are actually measuring. What is time anyway? According to Isaac Newton, both space and time were fixed attributes of the universe, a God-given stage on which events unfolded. But Albert Einstein torpedoed that idea with his theories of special and general relativity: the only thing that's fixed in the cosmos, he showed, is the speed of light.

Everything else--including space and time, which he melded into a single entity called space-time--is relative, as malleable as rubber. The Big Bang theory further established that space-time came into existence at a definite point in the past. Talking about what happened "before" the Big Bang is meaningless--as absurd as talking about what lies north of the North Pole.

This elasticizing of space-time means, for example, that observers might disagree over which of two events happened first--and both could be right. Even more bizarrely, physicists including Stephen Hawking have seriously discussed the possibility that relativity might make it feasible (though not with any technology we know of today) to send objects backward in time.

Does that mean you could go back, kill your own grandfather and keep yourself from being born--a seeming absurdity? Maybe not, say some physicists. In one interpretation of quantum physics, the world splits at each moment into an infinite number of universes that proceed in parallel; if you killed your grandfather, it might be in an alternate universe, so it would have no effect on the universe you inhabit.

Quantum physics demolishes the conventional concept of time in its own peculiar ways. Measured at short enough durations, space-time loses its apparently smooth, continuous structure, devolving into what Princeton physicist John Wheeler calls "quantum foam." The orderly flow of events may really be as much an illusion as the flickering frames of a movie. And according to independent physicist Barbour's new book, even the apparent sequence of the flickers is illusory.

It gets even worse. In some versions of M theory--the latest rage in physics, which attempts to meld relativity and quantum theory--there may be more than three dimensions of space and more than one dimension of time. What does that mean? Even the experts have no clue. "We're trying to understand it," says Harvard theorist Cumrun Vafa. "It's quite mysterious."

For physicists, then, time is an exceedingly complex and slippery concept. No wonder St. Augustine couldn't explain it. But when the month, the year, the century and the millennium end next week, it's a fair bet that theoretical physicists, like the rest of us, will be partying to welcome in the year 2000--whether it really exists or not.

--Reported by Mairi Brahim/London and Dick Thompson/Washington

With reporting by Mairi Brahim/London and Dick Thompson/Washington