The Secret Life of Time

Some nights—more than I like, lately—I wake to the sound of the bedside clock. The room is dark, without detail, and it expands in such a way that it seems as if I’m outdoors, under an empty sky, or underground, in a cavern. I might be falling through space. I might be dreaming. I could be dead. Only the clock moves, its tick steady, unhurried. At these moments I have the most chilling understanding that time moves in only one direction.

I’m tempted to look at the clock, but I already know that it’s the same time it always is: 4 A.M., or 4:10 A.M., or once, for a disconcerting stretch of days, 4:27 A.M. Even without looking, I could deduce the time from the ping of the bedroom radiator gathering steam in winter or the infrequency of the cars passing by on the street outside.

In 1917, the psychologist Edwin G. Boring and his wife, Lucy, described an experiment in which they woke people at intervals to see if they knew what time it was; the average estimate was accurate to within fifty minutes, although almost everyone thought it was later than it actually was. They found that subjects were relying on internal or external signals: their degree of sleepiness or indigestion (“The dark brown taste in your mouth is never bad when you have been asleep only a short time”), the moonlight, “bladder cues,” the sounds of cars or roosters. “When a man is asleep, he has in a circle round him the chain of the hours, the sequence of the years, the order of the heavenly bodies,” Proust wrote. “Instinctively he consults them when he awakes, and in an instant reads off his own position on the earth’s surface and the time that has elapsed during his slumbers.”

It may also be a simple matter of induction: it was 4:27 A.M. when I last woke at whatever hour this is, so that’s what time it is now. The surprise is that I can be so consistent. William James wrote, “All my life I have been struck by the accuracy with which I will wake at the same exact minute night after night and morning after morning.” Most likely it’s the work of the circadian clocks, which, embedded in the DNA of my every cell, regulate my physiology over a twenty-four-hour period. At 4:27 A.M., I’m most aware of being at the service of something; there is a machine in me, or I am a ghost in it.

And, once the ghost gets thinking, there is much to think about—most of all, how little time I have in which to do all the things I’m thinking about and how behind I am. Until very recently, that included a book about, of all things, the biology and perception of time, which had preoccupied me since before my kids—twin boys, Leo and Joshua, now ten—were born. In its wake is everything else: the melting ice caps; the cost of orthodontics; the rise of demagoguery; the gutters I have to clean before winter, if winter really comes. The end of the year is nearly here, and still my schedule is scattered across four productivity apps.

As worried as I am in these waking moments, I also find them oddly calming. It’s as if in falling asleep I’d fallen into an egg and woken as the yolk, cushioned and aloft on an extended present. It won’t last, I know. In the morning, the hours and minutes will reassert themselves and this seemingly limitless breadth of time will seem unreal and unreachable—the dream of boundless time, dreamed from the confines of an egg carton. But that’s a thought for tomorrow. For now, it’s now, and the tick of the bedside clock is the muffled beat of a heart.

For more than two thousand years, the world’s great minds have argued about the essence of time. Is it finite or infinite? Does it flow like a river or is it granular, proceeding in small bits, like sand trickling through an hourglass? And what is the present? Is now an indivisible instant, a line of vapor between the past and the future? Or is it an instant that can be measured—and, if so, how long is it? And what lies between the instants? “The instant, this strange nature, is something inserted between motion and rest, and it is in no time at all,” Plato remarked in the fourth century B.C.E. “But into it and from it what is moved changes to being at rest, and what is at rest to being moved.”

For St. Augustine, writing his “Confessions” in the year 397, time was even simpler: it’s us. Augustine was forty-three, beginning his tenure as an overwhelmed bishop in Hippo, a port city in North Africa, during the decline of the Roman Empire. The literature on time perception generally begins with Augustine, because he was the first to talk about time as an internal experience—to ask what time is by exploring how it feels to inhabit it. Time may seem slippery and maddeningly abstract, but it’s also deeply intimate, infusing our every word and gesture. Its essence, Augustine argued, can be gleaned from a single line of speech: “Deus creator omnium.”

“God, creator of all things.” Say it aloud or listen: in Latin, eight syllables, alternating short and long. “Each of these latter lasts twice as long as each of the former,” Augustine wrote. “I have only to pronounce the line to report that this is the case.” Yet how do we manage to make this measurement? The line is composed of syllables that the mind encounters in succession, one by one. How can the listener consider two syllables at once to compare their durations? How can one hold the longer syllable in mind? Its duration can’t be defined until it’s completed, but by then both syllables are gone. “Both have made their sound, and flown away, and passed by, and exist no more,” Augustine wrote, asking, “So what now exists for me to measure?”

Here Augustine arrived at an insight so fundamental that it’s taken as a given: time is a property of the mind. When you ask yourself whether one syllable lasts longer than another, you aren’t measuring the syllables themselves (which no longer exist) but something in your memory, “something fixed and permanent there.” The syllables leave an impression that persists in the present. Indeed, Augustine wrote, what we call three tenses are only one. Past, present, and future are all immediate in the mind—our current memory, our current attention, our current expectations. “There are three tenses or times: the present of past things, the present of present things, and the present of future things.” Augustine plucked time from the realm of physics and placed it squarely in what we now call psychology. “In you, my mind, I measure time,” he wrote. Words, sounds, and events come and go, but their passage leaves an impression: “Either time is this impression, or what I measure is not time.”

To consider this present is to glimpse the soul, Augustine argued. Modern science has abandoned the soul in favor of probing the framework of consciousness, a concept that is only slightly less elusive. Yet we share a rough idea of what’s meant: a lasting awareness of one’s self moving in a sea of selves, dependent yet alone, or a deep and common wish that “I” somehow belong to “we,” and that “we” belong to something even larger and less comprehensible; and the recurring thought, so easy to brush aside in the daily effort to get through our to-do lists, that our time matters precisely because it ends.

So much—all that matters, for Augustine—unfolds in a sentence. Recite a poem or a psalm by heart: your mind strains to recall what you’ve said and reaches forward to grab what you will say next. Memory pulls against expectation: “The vital energy of what I am doing is in tension between the two.” Vital energy: that’s the essence of Augustine, and of you, too, right now, as you absorb these words, strive to remember, and wonder what comes next. “Time is nothing other than tension,” Augustine wrote, “and I would be very surprised if it is not tension of consciousness itself.”

William James often could not sleep. In 1876, recently appointed to Harvard as an assistant professor of the nascent science of psychology, he lay awake thinking about his future wife, Alice Gibbens, with whom he was deliriously in love. “Seven weeks of insomnia outweigh many scruples,” he told her when he finally poured forth his desire in a letter. A decade later, he fretted in the dark about his years-long, two-volume, twelve-hundred-page book, “The Principles of Psychology,” which would become a classic almost as soon as it was published, in 1890. (Robert D. Richardson, in his biography “William James: In the Maelstrom of American Modernism,” notes that James’s insomnia worsened when his writing was going well; in the late eighteen-eighties, he resorted to using chloroform to fall asleep.) Perhaps, awake in the dark, James was annoyed by “the insipid image of a procession of sheep.” Or perhaps, like Augustine, he lay there absorbing the now. “Where is it, this present?” he wrote, in “Principles.” “It has melted in our grasp, fled ere we could touch it, gone in the instant of becoming.”

The array of subjects tackled in “Principles” included memory, attention, emotions, instinct, imagination, habit, the consciousness of self, and “automaton theory,” the persistent notion, of which James disapproved, that within our neural machinery lies some sort of homunculus, or mini-man, “that offers a living counterpart for every shading, however fine, of the history of its owner’s mind.” One of the more influential chapters is about the perception of time. It’s a deft synthesis of the work of other researchers and of James’s thoughts on the subject. In Europe, scientific interest was shifting from pure physiology to the neurological signalling underneath, abetted by a transition from philosophy to a more rigorous study of mind and cognition. In 1879, the first laboratory for experimental psychology opened in Leipzig, Germany, under Wilhelm Wundt, who sought to quantify sensation and inner experience. “The exact description of consciousness is the sole aim of experimental psychology,” Wundt wrote.

James didn’t believe in consciousness per se, by which he meant that it should not be addressed as some sort of extra-molecular mind-stuff. “Those who still cling to it are clinging to a mere echo, the faint rumor left behind by the disappearing ‘soul’ on the air of philosophy,” he wrote. Still, like Augustine, James felt that one could get a decent look at it by examining how we perceive the present.

Sit quietly, he proposed. Close your eyes, turn off the world, and try to “attend exclusively to the passage of time, like one who wakes, as the poet says, ‘to hear time flowing in the middle of the night, and all things moving to a day of doom.’ ” (James was paraphrasing Tennyson.) What do you find there? Likely very little; if you notice anything, he wrote, it’s a sense of the moments blooming one after another—“the pure series of durations budding, as it were, and growing beneath our indrawn gaze.”

In the late nineteenth century, before Einstein and relativity, scientists and philosophers were debating whether time was a real thing. Can we perceive a pure moment—a budding, blank duration? If so, we must have some special sense for it. (The Austrian experimentalist Ernst Mach even wondered if humans had distinct receptors, perhaps in the ears, that are attuned to it.) This seemed unlikely to James. You can’t perceive empty time any more than you can intuit a length or a distance with nothing in it. Look up into a clear sky: How far away is a hundred feet? A mile? With no landmarks for reference, you can’t say. It’s the same with time. If we perceive time’s passage, it’s because we perceive change, and for us to perceive change the time must be somehow filled; an empty duration alone won’t stimulate our awareness.

So what fills it? We do. “The change must be of some concrete sort—an outward or inward sensible series, or a process of attention or volition,” James wrote. In stopping to consider a seemingly empty moment, we fill it with a stream of thoughts. When you close your eyes and shut out the world, you still see a film of light inside your eyelids, “a curdling play of obscurest luminosity.” For Augustine, the present wasn’t something to observe; it is spoken and inhabited. Or perhaps it inhabits us—time is a volume, and we are its vessel. For James, it was the other way around: time is the container to our thoughts; the present moment is undefined without our mind to fill it.

Either way, in considering the moment right here before us, we can never quite escape ourselves. “We are always inwardly immersed in what Wundt has somewhere called the twilight of our general consciousness,” James reflected. “Our heart-beats, our breathing, the pulses of our attention, the fragments of words or sentences that pass through our imagination, are what people this dim habitat. In short, empty our minds as we may, some form of changing process remains for us to feel, and cannot be expelled.”

Even that formulation gives time too much credit. I lie awake in bed in the predawn hours, watching empty time flow. “We tell it off in pulses,” James wrote. “We say ‘now! now! now!’ or we count ‘more! more! more!’ as we feel it bud.” Time seems to flow in discrete units—it seems somehow independent and self-contained—not because we perceive units of empty time but because each of our acts of perception (or, more likely, our memories of those perceptions) is discrete. “Now” arises again and again only because we say “now” again and again. The present moment, James contended, is “a synthetic datum,” not experienced as much as manufactured. The present isn’t something we stumble through; it’s something we create for ourselves over and over, moment by moment.

We begin as cells, with one kind of time inscribed in our genes. Everything beyond that is learned, and the view among developmental psychologists going back to Piaget is that humans come to know time only gradually. One basic insight emerges in the first few months of life, when we learn to distinguish “now” from “not now”—although the seeds of this awareness probably reach us even sooner, while we’re still in the womb. Several researchers have demonstrated that human hearing becomes functional in the second trimester of gestation, and it’s been shown that the heart rate of a fetus quickens when it hears an audiotape of its mother reading a poem and slows when a female stranger reads the same thing—a recognition that requires a basic grasp of vocal rhythms. Not until about age four can children conceptually distinguish “before” from “after.”

One stage in this development is the dawning awareness of self. For the first three or four years of life, many researchers think, a child doesn’t distinguish between his own memories and ones that are recounted to him. Tell him about your trip to the Empire State Building, and he may later remember the event as if he’d gone himself. Recollection is itself so new that it’s as if all memories belonged to him. Gradually, he recognizes his memories as his alone, and so recognizes a self that persists: I am me, made up of my memories (I was me yesterday) and my expectations (I will be me tomorrow). The self is Augustine’s sentence of “now” stretched to a much greater length: “What is true of the poem as a whole is true equally of its individual stanzas and syllables. The same is true of the whole long performance, in which this poem may be a single item.”

One morning at the breakfast table, when our boys were about five, one of them described a nightmare he’d just had—the first dream he seemed to recall. He was walking in a wilderness when an invisible voice asked, “Who are you?” This blew my mind. It seemed obvious to me, if not to him, that the voice was none other than his own. So here were two selves confronting each other—one self unknown to itself—at least one of which was self-aware enough to ask humankind’s most existential question.

But once a new self realizes its continuity it pauses. “I will always be me”—always, how long is that? A self capable of noticing that everything around it expires can’t avoid concluding that it will, too, somehow, sometime. And so, right around the time that Joshua and Leo turned four, the hard questions began: What is “die”? Will you die? When will you die? Will I die? Are people made of meat? When I die, who will blow out my birthday candles—and who will eat my cake?

Years ago, long before I had children or was even married, a friend with children said, “The thing about having kids is that after a while you forget what it was like before you had them.” The idea was shocking. Busy enough with my own life, I couldn’t envisage a future self whose comings and goings were circumscribed, apparently happily, by the wants and needs of people half my size. But that’s what happened. As I grew into the role of parent, I sometimes felt as if I were taking apart a ship and using the planks to build a ship for someone else. I was building a ship across time, out of my time.

When the questions about death began, it was spring, slipping toward summer, and for weeks Leo was waking ever earlier. Maybe it was the light seeping into the room he shares with his brother, or the chorus of robins that erupts just before dawn. At 5:30 A.M., Joshua was fast asleep, his stuffed bunnies crushed against his face to keep out the day. But Leo, bright-eyed, would tiptoe into our room and hover by the bed. “I wanna play a game,” he whispered. He meant: You come, too.

We tried technology. The boys couldn’t tell time, so we bought a clock that resembles a traffic light. You set it for, say, six-forty-five, at which time the light changes from red to green—the signal that it’s O.K. to get up and make a racket. But it had the opposite effect. Leo would rise early, get sent back to bed, then lie awake staring at the red light with mounting impatience. Several times in the next hour, he’d pad into our room to announce in a whisper, “It’s not green yet.” Or he’d flop around and sigh so loudly that he’d wake his brother, and soon both of them would be chattering and laughing at the mystery of the red light’s intransigence. By the time six-forty-five arrived and the light turned green, an event they greeted with a cheer, their official release came as a relief to everyone.

At first, I let Leo go quietly downstairs by himself, and I mashed the pillow over my face and fell back asleep. But, increasingly, I found myself getting out of bed and following him. In September, the boys would enter kindergarten, and their lives would begin to expand furiously outward, away from us. Although it was gradual, we sensed that we were on the brink of a transformation, and the days took on a crystalline quality, as if we’d already begun to view them from memory.

The boys sensed it, too, if only from us. A quiet half hour alone with one boy—by his request, no less—was a gift. Leo and I sat on the wood floor, with the back door open to the sound of the robins, and played another round of Bingo, or checkers, or (so help me) Mousetrap, until Joshua came shuffling in, gruff and rumple-headed—like me without coffee—and issued his own directives, one sentence budding into the next: Now. Now. Now. ♦

Alan Burdick, a staff writer, joined The New Yorker in 2012, first as a senior editor and then also as the editor of Elements, newyorker.com’s science-and-tech blog. He worked previously as an editor at the Times Magazine, Discover, and OnEarth, and as a writer and producer at the American Museum of Natural History. He has written for magazines including Harper’s and GQ, and is the author of “Out of Eden: An Odyssey of Ecological Invasion,” which, in 2005, was a finalist for the National Book Award and won the Overseas Press Club Award for environmental reporting.