Clock-watching

Why Time Flies: A Mostly Scientific Investigation. By Alan Burdick. Simon & Schuster; 320 pages; $28.

TIME is such a slippery thing. It ticks away, neutrally, yet it also flies and collapses, and is more often lost than found. Days can feel eternal but a month can gallop past. So, is time ever perceived objectively? Is this experience innate or is it learned? And how long is “now”, anyway? Such questions have puzzled philosophers and scientists for over 2,000 years. They also began to haunt Alan Burdick of the New Yorker. Keen for answers, he set out “on a journey through the world of time”, a lengthy trip that spans everything from Zeno’s paradoxes to the latest neuroscience. Alas, he arrives at a somewhat dispiriting conclusion: “If scientists agree on anything, it’s that nobody knows enough about time.”

Humans are apparently poor judges of the duration of time. Minutes seem to drag when one is bored, tired or sad, yet they flit by for those who are busy, happy or socialising (particularly if alcohol or cocaine is involved). Eventful periods seem, in...