World’s timekeepers upend how they adjust time to avoid catastrophic ‘negative second’

On 15 October, member states of the General Conference on Weights and Measures (CGPM) voted to scrap the ‘leap second’ — periodic adjustments to the world’s clocks to align time given by the sun’s position in the sky, with the more stable ticking of atomic clocks, known as Universal Coordinated Time. The CGPM had previously voted to ditch leap seconds by 2035, but yesterday’s decision had immediate effect. The leap second’s replacement — the ‘leap hour’ — probably won’t be needed for thousands of years, effectively pushing the issue onto future generations.