Is Time Running Out for the Leap Second?

The destiny of the leap second is extra than simply the destiny of the leap second. At stake is Coordinated Common Time, the worldwide customary for timekeeping, which the continued existence of the leap second is slowly undermining.

Coordinated Common Time, or U.T.C., is tenderly constructed from readings made by atomic clocks stored at nationwide laboratories around the globe. These clocks tick off, or “understand,” their finest seconds and ship the measurements to the B.I.P.M. There, timekeepers painstakingly assemble the readings — averaging, weighting, adjusting for discrepancies — into a great second for everybody in every single place to agree on and make use of, sometimes including leap seconds as wanted. This meeting course of takes time. And so as soon as a month the Bureau publishes the right time within the type of a publication, known as Round T, that tells every nationwide clock how a lot it diverges from the worldwide customary, to assist it enhance its goal the next month.

Coordinated Common Time is the world’s official time scale, and can proceed to be whether or not or not it incorporates leap seconds. International time zones are described in reference to it. (New York time presently is U.T.C. minus 5 hours.) And the beating coronary heart, the second, is crucial within the constellation of ordinary measurements overseen by the B.I.P.M., alongside the meter (size), kilogram (weight), kelvin (temperature), candela (depth of sunshine), ampere (electrical present) and mole (quantity of substance).

The thought, formalized a century and a half in the past by nationwide signatories to a world treaty known as the Meter Conference, is that every unit of measurement must be similar in every single place on this planet; one meter in Spain is exactly one meter in Singapore. The seven customary models are integral to honest commerce, reproducible science and dependable know-how. The second is extra-special as a result of it underpins all the opposite models besides the mole. As an illustration, the meter is outlined as the space mild travels in a vacuum throughout one-299,792,458ths of a second, and the kilogram was lately redefined when it comes to the second.

As well as, the second is tethered to a time scale, or movement of seconds. A key tenet of contemporary life is that not solely should the unit of time be similar regardless of the place it’s measured, so should the movement of seconds of which the one is a component.

However the leap second is placing that tenet is in danger. The kludge is so technically troublesome for digital know-how to include that different, ersatz strategies of timekeeping — unofficial, however freed from leap seconds and simpler to implement — have begun to displace U.T.C., in keeping with a current article within the journal Metrologia. To supporters of Decision D, eradicating the leap second from U.T.C. would make the usual time scale friendlier to fashionable digital know-how, a minimum of within the century following 2035. Coordinated Common Time would nonetheless be common, simply not coordinated with Earth time.