Time Travel. A History

In 1880 the United Kingdom enacted a legislative definition of time, the Statutes (Definition of Time) Act. This declared itself to be “an Act to remove doubts as to the meaning of Expressions relative to Time occurring in Acts of Parliament, deeds, and other legal instruments.” It was enacted “by the Queen’s most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal [Time Lords!], and Commons.” If only these wise men and woman could have solved the problem by fiat. Removing doubts about the meaning of time is an ambitious goal. Alas, it turns out that they were not dealing with What is time? but only What is the time? The time in Great Britain, as defined by the act, is Greenwich mean time.^*5

What is time? At the dawn of the written word, Plato struggled with the question. “A moving image of eternity,” he said. He could name the parts of time: “days and nights and months and years.” Moreover:

When we say that what has become is become and what becomes is becoming, and that what will become is about to become and that the nonexistent is nonexistent—all these are inaccurate modes of expression. But perhaps this whole subject will be more suitably discussed on some other occasion.

Here Aristotle, too, found himself in difficulties. “To start, then: the following considerations would make one suspect that it either does not exist at all or barely, and in an obscure way. One part of it has been and is not, while the other is going to be and is not yet.” The past has gone out of existence, the future has not yet been born, and time is made up of these “things which do not exist.” On the other hand, he said—looked at differently—time seems to be a consequence of change, or motion. It is “the measure” of change. Earlier and later, faster and slower—these are words that are “defined by” time. Fast is a lot of motion in a little time, slow is a little motion in a lot of time. As for time itself: “time is not defined by time.”

Later, Augustine, like Plato, contrasted time with eternity. Unlike Plato, he could hardly stop thinking about time. It obsessed him. His way of explaining was to say that he understood time very well, until the moment he tried to explain. Let us reverse Augustine’s process: stop trying to explain and instead take stock of what we know. Time is not defined by time—that needn’t paralyze us. When we leave aside the search for epigrams and definitions, it turns out we know a great deal.^*6

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WE KNOW THAT time is imperceptible. It is immaterial. We cannot see it, hear it, or touch it. If people say they perceive the passing of time, that’s just a figure of speech. They perceive something else—the clock ticking on the mantel, or their own heartbeat, or other manifestations of the many biological rhythms below the level of consciousness—but whatever time is, it lies outside the grasp of our senses. Robert Hooke made this very point to the Royal Society in 1682:

I would query by what Sense it is we come to be informed of Time; for all the Information we have from the senses are momentary, and only last during the Impressions made by the Object. There is therefore yet wanting a Sense to apprehend Time; for such a Notion we have.^*7

Yet we experience time in a way that we do not experience space. Close your eyes, and space disappears: you may be anywhere; you may be big or small. Yet time continues. “I am listening not to Time itself but to the blood current coursing through my brain, and thence through the veins of the neck heartward, back to the seat of private throes which have no relation to Time,” says Nabokov. Cut off from the world, with no sensory perception, we may still count the time. Indeed, we habitually quantify time (“…and yet we conceive of it as a Quantity,” said Hooke). This leads to a plausible definition: Time is what clocks measure. But what is a clock? An instrument for the measurement of time.^*8 The snake swallows its tail again.

Once we conceive of time as a quantity, we can store it up, apparently. We save it, spend it, accumulate it, and bank it. We do all this quite obsessively nowadays, but the notion is at least four hundred years old. Francis Bacon, 1612: “To choose Time, is to save Time.” The corollary of saving time is wasting it. Bacon again: “Prolix and florid Harangues…and other personal Speeches are great Wasters of Time.” No one would have begun thinking about time as a bankable commodity who was not already familiar with money. Time hath, my lord, a wallet at his back, / Wherein he puts alms for oblivion. But is time really a commodity? Or is this just another shabby analogy, along with time the river?