Time Travel. A History

Heraclitus was saying something important: namely, that things change. The world is in flux. That may seem self-evident, but his approximate contemporary Parmenides took a different view: change is an illusion of our senses; beneath the transitory world of appearances lies the true reality—stable, timeless, eternal. This was the view that appealed to Plato.

Notice that no one so far is saying that time is like a river. The universe is like a river. It flows. (Or it doesn’t, if you’re Plato.)

Alfred Jarry, constructing his time machine in 1899, said it had already become “a banal poetic figure to compare Time to a flowing stream.”^*2 Banality didn’t stop anyone. “Time, that impalpable and fatal river,” the Parisian astronomer Charles Nordmann said in 1924, “strewn with dead leaves, our wistful hours carried down stream.” Where are we in this picture—we, the conscious observer? We are merely a bump in the viscosity, said the absurdist Jarry. The Christian hymn says, “Time, like an ever rolling stream / Bears all its sons away.” The river carries us toward eternity, which is to say past death. Miguel de Unamuno wrote, “Nocturno el río de las horas fluye…”—though he imagined it flowing from the future,

“el mañana eterno.” Marcus Aurelius, Stoic philosopher and emperor, said that time is a river because everything rushes by, while we watch. “No sooner has anything appeared than it is past, and now another thing is passing, and that yonder will presently be here.”

If time is a river, can we ask how fast it flows? That seems a natural question to ask about a river, but it’s not a good question to ask about time itself. How fast does time flow? Measured how? We have plunged into a tautology. It’s no better to ask, How fast are we advancing through time?

Riverine flow can be complicated. Can temporal flow? “There is a theory,” explains Spock in a classic episode of Star Trek. “There could be some logic to the belief that time is fluid, like a river, with currents, eddies, backwash.”

If time is a river, does it have tributaries? Whence does it spring? From the big bang, or are we now mixing metaphors? If time is a river, where are the banks that contain it? W. G. Sebald asked that question in his last novel, Austerlitz:

Where, seen in those terms, where are the banks of time? What would be this river’s qualities, qualities perhaps corresponding to those of water, which is fluid, rather heavy, and translucent?

Sebald also asked, “In what way do objects immersed in time differ from those left untouched by it?” This was a nice conceit: that some parts of our world, like dusty, shuttered rooms, may stand outside of time, may be cut off from time, immune to the flow.

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IN POINT OF FACT, time is not a river. We possess a great metaphorical tool kit with utensils for every occasion. We say that time passes, time goes by, and time flows, and all those are metaphors. “Time is a fluid medium for the culture of metaphors,” writes Nabokov metaphorically. We also think of time as a medium in which we exist. And as a quantity that we can possess, waste, or

save. Time is like money, it is like a road, a path, a maze (Borges again, of course), a thread, a tide, a ladder, and an arrow. All at once.

“The idea that Time ‘flows’ as naturally as an apple thuds down on a garden table implies that it flows in and through something else,” says Nabokov, “and if we take that ‘something’ to be Space then we have only a metaphor flowing along a yardstick.”

Is it even possible to talk about time without using metaphors? Perhaps:

Time present and time past

Are both perhaps present in time future,

And time future contained in time past.

Although, if that isn’t metaphor, what trope is it? Pregnant words: “present in…”; “contained in…” In the same poem T. S. Eliot also had some words about words.

Words strain,

Crack and sometimes break, under the burden,

Under the tension, slip, slide, perish,

Decay with imprecision, will not stay in place,

Will not stay still.

Everything was so unsettled about time. Philosophers, physicists, poets, and pulp writers all struggled. They were using the same word bag. They drew their tiles and moved them around the playing board. (Slip, slide, perish, decay with imprecision.) Philosophers’ words alluded to the philosophers’ words that came before. Physicists’ words were special, more precisely defined, and anyway they were mostly numbers. Physicists don’t generally call time a river. They don’t generally depend on metaphor; at least, they don’t like to admit it. Even “arrow of time” is not so much a metaphor as a catchphrase.