Does time have a future? Yes, but how much of a future depends on what the ultimate fate of the cosmos turns out to be.
What Einstein had shown was that there is no universal “now.” Whether two events are simultaneous is relative to the observer. And once simultaneity goes by the board, the very division of moments into “past,” “present,” and “future” becomes meaningless. Events judged to be in the past by one observer may still lie in the future of another; therefore, past and present must be equally definite, equally “real.” In place of the fleeting present, we are left with a vast frozen timescape—a four-dimensional “block universe.”
.. In 1949, on the occasion of Einstein’s seventieth birthday, Gödel presented him with an unexpected gift: a proof of the nonexistence of time. And this was not a mere verbal proof, of the sort that philosophers like Parmenides, Immanuel Kant, and J. M. E. McTaggart had come up with over the centuries; it was a rigorous mathematical proof.
.. Hawking says that asking what came before the Big Bang is as silly as asking what’s north of the North Pole.
.. Arthur Eddington, one of the first physicists to grasp Einstein’s relativity theory, declared that our intuitive sense of time’s passage is so powerful that it must correspond to something in the objective world. If science cannot get a purchase on it, one might say: Well, so much the worse for science!
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. John Archibald Wheeler, one of the great physicists of the twentieth century, took to quoting this in a scientific paper: “Time is nature’s way to keep everything from happening all at once.” In a footnote, Wheeler writes that he discovered this quote among graffiti in the men’s room at the Pecan Street Café in Austin, Texas. That such an eminent thinker would resort to quoting from a men’s-room wall isn’t surprising if you consider the contemporary free-for-all among physicists and philosophers and philosophers of physics over the nature of time. Some maintain that time is a basic ingredient of the universe; others say, no, it emerges from deeper features of physical reality. Some insist that time has a built-in direction; others deny this. (Stephen Hawking once claimed that time could eventually reverse itself and run backward, only to realize later that there had been a mistake in his calculations.) Most physicists and philosophers today agree with Einstein that time’s passage is an illusion; they are eternalists. But a minority—who call themselves “presentists”—think that now is a special moment that really advances, like a little light moving along the line of history; this would still be true, they believe, even if there were no observers like us in the universe.
If there is one proposition about time that all scientifically inclined thinkers can agree on, it might be one due to the nonscientist Hector Berlioz, who is reputed to have quipped, “Time is a great teacher, but unfortunately it kills all its pupils.”