Near Versailles, vote to abolish leap seconds — ABC News Australia

The governing body of the International Bureau of Weights and Measures (BIPM) will vote at a meeting near Versailles, France, on October 12–15 on ending the practice of adding leap seconds to Coordinated Universal Time (UTC). Such seconds were introduced to synchronize ultra-precise atomic time with the uneven rotation of the Earth, ABC News Australia reports.

Leap seconds have been used since 1972. During that time, they have been added 27 times, most recently at the end of 2016. The Earth’s rotation is generally slowing, including because of the Moon’s influence, but over short periods the planet can rotate faster. Since around 2020, the Earth’s rotation speed has increased.

A problem for software

UTC is based on atomic clocks, while the length of an Earth day can differ by milliseconds. For satellite navigation and other technologies that require measurements of fractions of a millisecond, the traditional definition of a second as 1/86,400 of a day is not precise enough.

More current news is available on the UA.News Telegram channel Telegram.

Adding a leap second creates difficulties for computer systems because software usually assumes that time only moves forward and that a minute always has 60 seconds. In the past, such adjustments caused disruptions, including on the Cloudflare platform and the Reddit website. Leap seconds are irregular, and they are planned only six months before the adjustment.

A possible leap hour

In 2022, the BIPM governing body decided to abandon leap seconds by 2035 and discuss another way to align UTC with the Earth’s rotation. The need to accelerate this timetable was linked to the possibility of the first negative leap second in history, under which time would have to jump forward by one second. This option has not yet been used, so the relevant software has not been tested.

The main proposal is to allow UTC to gradually drift away from time linked to the Earth’s rotation until the difference reaches one hour. A “leap hour” would then be introduced. The Earth currently loses less than one second per year, so the need for such an adjustment may arise more than a thousand years from now.