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From cesium atoms to circadian rhythms, a journalist probes the notion of “now”

Why Time Flies: A Mostly Scientific Investigation

Alan Burdick
Simon and Schuster
317 pp.
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“Time is what everybody agrees the time is,” a researcher says to Alan Burdick a few pages into Why Time Flies: A Mostly Scientific Investigation. It sounds like something the Mad Hatter might have said in Alice’s Adventures in Wonderland. But it’s the truth.

Time is such a fundamental part of modern life that sometimes we forget how it insinuates itself into everything that we do. In this, his second book, New Yorker staff writer Alan Burdick deftly counts the ways.

For instance, how do we keep accurate time? It’s not so simple. Since the 1930s or so, Earthlings have relied on the fact that a quartz crystal vibrates at exactly 32,768 times per second. Many wristwatches and quartz clocks have a crystal inside them, steadily and invisibly vibrating, marking time.


Time is said to slow down during periods of extreme stress, but this commonly made claim has proven difficult to study in the laboratory.

For even greater accuracy, an atom of cesium vibrates 9,192,631,770 times per second. Across the world, there are several hundred cesium clocks, each the size of a suitcase and incredibly accurate. In the United States, the National Institute of Standards and Technology has a dozen of them. But even they will disagree with one another. They are averaged to compensate for slow and fast clocks.

Our cellphones are not reliant on cesium atoms; they get their time instead from an array of satellites orbiting Earth. And scientists now measure events that take place in femtoseconds (one-quadrillionth of a second) and attoseconds (one-quintillionth of a second, or the time it takes for light to travel the length of two hydrogen atoms).
Not so long ago, Burdick writes, time was less certain. Most large cities had an observ-
atory and a dedicated timekeeper who kept time on the basis of the positions of stars. The degree of human error was extreme. In the United States alone, before 1883, there weren’t just four time zones but dozens of them. Every town had its own time.

Before 1670, when grandfather clocks got a seconds pendulum, seconds were little more than a strange abstraction, like an atom or the surface of the Moon. Three hundred years later, Coordinated Universal Time (UTC), or world time, arrived—an agreement that began among 17 nations and has expanded to include 58. Even so, some countries opted out. India, for instance, in its geographic vastness, operates on a single time zone (Indian Standard Time), which differs from UTC in multiples of 30 min rather than an hour.

Biological cells keep their own kind of time. We are a trillion clocks. Organs tick, systems tock. Sometimes a donated kidney adapts to the recipient’s circadian rhythms, and sometimes it doesn’t—it keeps donor time instead. Even microscopic cyanobacteria, which divide every 5 or 6 hours, regulate gene expression on a strict 24-hour schedule, which is closely linked to the rhythms of the light-dark cycle.

In his search for temporal meaning, Burdick takes us on a journey around the world. He travels to the International Bureau of Weights and Measures in Paris to speak with the people who keep the world at the correct time. In the Arctic, he experiences a few weeks of what essentially is one 3-month-long day—constantly lit, the Sun always in the sky. He introduces us to the work of Michel Siffre, a French scientist who descended into speleological darkness, living in caves for months at a time to investigate how malleable our circadian rhythms are. The answer: a little, but not a lot. During these excursions, the book zips along. It is erudite and informative, a joy with many small treasures.

In Dallas, Texas, with neuroscientist David Eagleman, Burdick throws himself from a tower into a waiting net to investigate whether time really slows down during stressful situations, his panicked eyes trained on an adapted wristwatch. We learn that children don’t even start to understand concepts such as “before” and “after” until preschool and consider why old people think time begins to move faster and faster as they age.

Occasionally, Burdick spends perhaps a little too long on work that could have been briefly encapsulated. He can be comprehensive to a fault. And the ongoing neuroscientific work on time is described but feels unresolved—precisely because it is.

We become acquainted with thought experiments that have kept philosophers busy for centuries. But they are riddles with no answers: When is now? Is now now? Does now first have to become a then before we can understand that it was a now? How long is the present? How far apart can two things be and still be part of the same moment?

In these sections, I must confess that time seemed to stall a little. But even that taught me something about time, and a few pages later I was flying again.

About the author

The reviewer is at the Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503.