Against the Clock

Time travel’s improbable legacy in literature and science

In June 2016, the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, hosted a conference on the subject of “Time in Cosmology.” One of the questions debated by the attendees was the reality of time. Do past, present and future exist in any meaningful sense? Any expectation that physicists might have a comprehensive answer to that venerable question would not have survived exposure to even a single seminar. “If I bang my head against the wall,” physicist Avshalom Elitzur told journalist Dan Falk, “it’s because I hate the future … The future does not exist. It does not! Ontologically, it’s not there.” Others begged to differ.

The nature of time, in other words, remains as mysterious to modern science as it seemed to Aristotle and St. Augustine, and as wonderfully perplexing as it probably still seems to an undergraduate philosophy student after a couple of bong hits. What, then, are we to make of time travel? By all rights...