Why Time Is an Illusion

When we suddenly have a lot of time on our hands, our thoughts are more likely to turn to time. The coronavirus lockdown has given millions of people more idle hours than they’ve had in years. It’s not surprising that so few enjoy it: Unmoored from routines and commitments, from train, class, and movie schedules, time looms more as entity than indicator, something not to be harnessed, as in better days, but to be wrestled with.

It’s the perfect moment, then, for Joseph Mazur’s new book, The Clock Mirage: Our Myth of Measured Time. In a work as comfortable with physics as with psychology, Mazur reviews our species’ long engagement with days, hours, and seconds, as well as modern discoveries about the body’s internal clock. “Time has something to do with our pulses, yes,” Mazur writes, “but it has more to do with our cells and brains, things that update memories to tell our bodies that we are in the rhythms and beats of being alive.”

The advent of measured time changed human life. We no longer ate and slept when we were hungry or tired, but when the clock told us to. “Abstract time became the new medium of existence,” Mazur writes, and time became a commodity. Time proceeds apace with or without human perception, but that can be a challenge for a myopic population to grasp. Britain’s delayed shift from the Julian to the Gregorian calendar in 1752, for example, had September 2 followed by September 14, and some rioted to regain their “lost” 11 days.

But clock time also unifies the world in some essential ways. As train travel expanded in the mid-19th century, disparate time in different locations threatened to make scheduling (and avoiding crashes) impossible. In 1860, localities based their clock time on the position of the sun at noon. At 12 p.m. in Washington, D.C., it was 12:12 in New York, and 12:24 in Boston. The 1884 International Meridian Conference brought noon to heel with the designation of the Prime Meridian in Greenwich, England.

What Makes a Moment?

Every science is in some ways a study of time, as there is no research goal for which time is not a variable. And yet even defining a moment—the duration between past and future—has challenged us at least since Zeno and other Greek thinkers debated whether the progress of an arrow represented continuous flight, a series of individual movements, or both. Even if we can’t know for certain, we can come to grasp how we experience it: “A rapid succession of nows, each much like the next,” as Mazur describes it, “except for a very slight change, is interpreted as a continuous flow of time.”

So just how long is a perceived human moment? No longer than 40 milliseconds, according to German neuroscientist Ernst Pöppel, who calls that duration, or time quanta, a building block of consciousness. Physicists aim for more precision, and believe they have captured the “second” in atomic clocks, which time it at 9,192,631,770 radiation periods of cesium-133—and yet even those clocks are conventional, and imperfect: They drop a second every 20 million years.

How We Live Right Now

Mazur alternates his chapters with interludes in which he discusses lived time with those who have done it to the extreme—athletes, astronauts, long-haul truckers, prisoners, and a pilot who utters the universal truth, “Going home always seems quicker.”

Their insights illustrate a key aspect of experienced time: It’s imaginary, Mazur writes, “a deception that helps us cope with our indefatigable lust for explaining and organizing our world.”

Putting a number on time, according to Mazur, “is just an appearance of time, not time itself.” Without the clock that registers it, “it has no existence beyond its personal effects on memory and destiny.” We can use enumerated time to fool ourselves, setting clocks five minutes ahead, say, to make ourselves rush. But we can’t capture it.

If we discarded our clocks, Mazur argues, we’d soon understand just how much of a mirage our conception of time is. In experiments involving people moving into windowless, clockless spaces, and in the records of cave explorers ensconced underground for weeks or months, individuals lost track of external time, falling into rhythms determined by their own bodily functions, which diverged widely from a 24-hour cycle. Some fell into sleep-wake cycles of 36 hours on and 12 hours off, while others stopped noticing the difference between 18 hours of sleep and two.

We don’t need to move into a cave to understand how variable time can be; we just need to age. There is an internal clock in our bodies that is based in the hypothalamus and piloted by our genes, the effect of light on the retina, and, probably even more strongly, cultural conventions. Research makes clear that, in our minds, perceived time flies when we have happy experiences, slows down when things are dull, and nearly halts in times of danger or extreme stress—one reason we remember such moments so vividly.

But above all, our circadian systems weaken with age; we sleep less, so there’s more time available to us, but it goes faster. One possible reason: Fewer landmark moments, like first kisses, first cars, and first children. We don’t pay as much attention to routine moments, so when we start having fewer memorable ones, we feel time speed up. Young people, however, think about the passing of time much more; they watch the clock more closely, get bored more easily, and hunger for novelty.

We make decisions based on the past, with consideration for the future, but always in, and for, the now. But “the now becomes the past in a flash,” and we are powerless to stop it. Mazur has written a book for our moment, because, for all of its scope, it comes to the same conclusion each of us must concede: Time is humbling.

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