Signing you in

Listen 00:00 0.5x 0.75x 1x 1.25x 1.5x 2x AI Narration This audio is AI generated.

Time”, remarked Ford Prefect in The Hitchhiker’s Guide to the Galaxy, “is an illusion. And lunchtime doubly so.” The line from Douglas Adams’s masterpiece has been quoted by generations of young people, as they discover the joys of philosophy, science and the philosophy of science through a sci-fi comedy. Even if Prefect was right, the illusion is powerful. Getting the “real time” wrong can have pretty serious consequences. In the quest for temporal accuracy, the time lords have decided to grant the world a “leap hour”.

The quest for accuracy in measuring time is not merely the province of obsessive bosses. For the physicist and the computer engineer, the difference of even a few fractions of a second can cause problems for experiments and software that the digital world runs on. Subtle shifts in the Earth’s rotation have, since at least 1955 and the advent of atomic clocks, caused scientists to introduce ad hoc “leap seconds” — the more common “leap day/year” is more than two millennia old. Last week, delegates from 69 countries to the International Bureau of Weights and Measures voted in France to do away with leap seconds and collect wayward moments into a “leap hour”.

There are sound reasons for the shift: The risk to computer systems is lower. That said, there was something mystical about the uncertainty of the most certain measuring devices, the drama of a second gained and lost. Fortunately, lunchtime, at least, remains an illusion more subject to appetite than the clock.