Timekeeping bodies meet at Versailles to vote on ending the leap second

Left · 2Delegates of the International Bureau of Weights and Measures (BIPM), which standardises the world's measurements, are meeting at Versailles, near Paris, to vote on whether to abandon the leap second. 1 2 Left · 2ABC News (Australia) says the BIPM's governing body will vote at its meeting on 12–15 October, while Al Jazeera describes the debate and vote as taking place on Thursday 15 October. 1 2 Left · 2Leap seconds are added to Coordinated Universal Time (UTC), which is based on atomic clocks, to keep it aligned with Earth's rotation, which is irregular and generally slowing. 27 have been added since 1972, the last on 31 December 2016. 1 2

Left · 2Both outlets say leap seconds cause trouble for computer systems. Al Jazeera cites 2012 crashes at LinkedIn and Reddit and a collapse of Qantas bookings, and ABC says they have previously crashed Cloudflare and Reddit; Darryl Veitch of the University of Technology Sydney said they break software assumptions that time only moves forwards and a minute has 60 seconds. 2 1 Left · 2In 2022 the BIPM voted to abandon the leap second by 2035. ABC says the decision was fast-tracked because Earth has sped up since about 2020, which could require the first "negative" leap second, a move Veitch warned has never been tested in software, while Michael Wouters of Australia's National Measurement Institute considers it less likely to cause problems. 1 2 Left · 1Al Jazeera reports that the resolution before the member states would scrap the leap second by 2027, with accepted proposals expected to take effect on 20 May 2027, and that Russia has wanted to push the date back to 2040 because its GLONASS satellite-navigation system incorporates leap seconds. 2

Left · 1Al Jazeera adds that the BIPM will consider two other proposals: redefining the second using optical frequencies, which are now more precise than atomic clocks, and aligning Earth timekeeping with a time standard NASA is developing for the Moon. 2 Left · 2ABC says the leading proposal is to let UTC drift until it is an hour out of sync and then observe a "leap hour", which could take more than a millennium to become necessary; Al Jazeera notes that the gap would reach about 54 seconds by 2100 and several hours in two millennia, putting sunrise and sunset out of step with clocks. 1 2 Left · 1Wouters said some people object philosophically because it disconnects how time is counted from experience of it, while ABC also quotes Lucia McCallum of the University of Tasmania saying it does not matter if UTC is seconds behind Earth's days. 1