Time Travel. A History

Augustine was right all along. The modern philosopher J. R. Lucas, in his Treatise on Time and Space, comes back around: “We cannot say what time is, because we know already, and our saying could never match up to all that we already know.” So was the Buddha (as translated via Borges): “The man of a past moment has lived, but he does not live nor will he live; the man of a future moment will live, but he has not lived nor does he now live; the man of the present moment lives, but he has not lived nor will he live.” We know that the past is gone—it is finished, done, signed, sealed, and delivered. Our access to it is compromised, limited by memories and physical evidence—fossils, paintings in attics, mummies, and old ledgers. We know that eyewitnesses are unreliable and records can be tampered with or misread. The unrecorded past no longer exists. Still, experience persuades us that the past happened and keeps happening. The future is different. The future is yet to come; it is open; not everything can happen but many things can. The world is still under construction.

What is time? Things change, and time is how we keep track.

*1 Die Zeit ist nicht. But he adds, Es gibt Zeit. Time is given.

*2 Beth Gleick, Time Is When (Chicago: Rand McNally, 1960). The present author’s mother.

*3 “Time!”

*4 “By a curious caprice,” wrote the astronomer Charles Nordmann in 1924, “the French language, different from others, designates by a single word, the word temps, two very different things: the time which goes by and the weather, or state of the atmosphere. This is one of the peculiarities which give to our language its hermetic elegance, its concentrated sobriety, its elliptic charm.”

*5 Even this attempt at definition proved tricky. A test case came on August 19, 1898, at 8:15 p.m. (Greenwich mean time), when a man named Gordon was nicked by the police in Bristol for riding his bicycle without a lamp. The local law clearly stated that every person riding a bicycle (which fell under the definition of “carriage”) shall carry a lamp, so lighted as to afford adequate means of signaling the approach of the bicycle, during the period between one hour after sunset and one hour before sunrise. On the evening in question, sunset in Greenwich had occurred at 7:13 p.m., so Gordon was caught riding lampless a full hour and two minutes after sunset.

This did not sit well with the accused man, because the sun set ten minutes later in Bristol than in Greenwich: 7:23, not 7:13. Nonetheless, the justices of the city of Bristol, relying on the Statutes (Definition of Time) Act, found him guilty. After all, they reasoned, everyone would benefit by having “a readily ascertained time of lighting up.”

With the help of his solicitors, Darley & Cumberland, poor Gordon appealed. The question before the Court of Appeals was described as “an astronomical one.” The appellate court saw it his way. They ruled that sunset is not a “period of time” but a physical fact. Justice Channell was insistent: “According to the decision of the Justices, as it stands, a man on an unlighted bicycle may be looking at the sun in the heavens, and yet be liable to be convicted of the offence of not having his lamp lighted an hour after sunset.”

*6 “If you stop, in dealing with such words, with their definition, thinking that to be an intellectual finality, where are you? Stupidly staring at a pretentious sham! ‘Deus est Ens, a se, extra et supra omne genus, necessarium, unum, infinite perfectum, simplex, immutabile, immensum, aeternum, intelligens,’ etc.,—wherein is such a definition really instructive? It means less than nothing, in its pompous robe of adjectives.”—William James

*7 Hooke proceeded to dig himself into a hole. “I say, we shall find a necessity of supposing some other Organ to apprehend the Impression that is made by Time.” What organ? “That which we generally call Memory, which Memory I suppose to be as much an Organ as the Eye, Ear or Nose.” Where is this organ, then? “Somewhere near the Place where the Nerves from the other Senses meet.”

*8 Lee Smolin tries to escape the circularity in Time Reborn by redefining “clock”: “For our purposes, a clock is any device that reads out a sequence of increasing numbers.” Then again, a person counting to one hundred is not a clock.

*9 McTaggart’s name bears explaining. He was christened (by his parents, the Ellises of Wiltshire) John McTaggart Ellis, after his father’s uncle, Sir John McTaggart, a childless Scottish baronet. Sir John then bequeathed a considerable fortune to the Ellises on the condition that they take his surname. In the case of young John, this led to a redundancy. The double dose of “McTaggart” never seems to have bothered him, and he, not the baronet, is the McTaggart most remembered today.