Scientists and government officials meeting at a conference in France voted on Friday to end the transition by 2035, the world’s watchdog said.
As with leap years, leap seconds are periodically added to clocks over the years to make up for the difference between actual atomic time and the slow rotation of the Earth.
Although leap seconds pass unnoticed by most people, they can cause problems for various systems that require real, uninterrupted time, such as satellite navigation, software, telecommunications, commerce, and even space travel.
It has caused a stir at the International Bureau of Weights and Measures (BIPM), which is responsible for Coordinated Universal Time (UTC) – the internationally agreed standard by which the world sets its clocks.
The decision to stop adding seconds by 2035 was made by the 59 member states of the BIPM and other parties at the General Conference on Weights and Measures, which is held approximately every four years at the Versailles Palace west of Paris.
The head of the BIPM’s time department, Patrizia Tavella, told AFP that the “historic decision” will allow “continuous movement of the seconds without the interruptions caused by leap seconds”.
“The change will be effective by 2035 or earlier,” he said via email.
He added that Russia voted against the resolution, “not on principle”, but because Moscow wants to push the date of entry into force to 2040.
Some countries called for a faster deadline such as 2025 or 2030, so the “best compromise” was 2035, he said.
The United States and France were among the countries that led the revolution.
Tavella stressed that “the connection between UTC and the rotation of the Earth has not been lost”.
“Nothing will change” for the people, he added.
A leap moment?
Seconds have long been measured by astronomers who analyzed the rotation of the Earth, but the advent of atomic clocks – which use atoms at regular intervals like tick-tock machines – brought more precise timekeeping.
But the slow rotation of the Earth means that these two times are out of sync.
To bridge the gap, leap seconds were introduced in 1972, and 27 have been added at intervals since – the last in 2016.
Under the assumption, leap seconds will continue to be added as normal for now.
But by 2035, the gap between atomic and cosmic time will be allowed to grow to a value greater than one second, Judah Levine, a physicist at the US National Institute of Standards and Technology, told AFP.
“The significance is still unknown,” said Levine, who spent years helping draft the resolution along with Tavella.
Discussions will be held to get ideas by 2035 to determine its value and how it will be used, according to the decision.
Levine said it is important to protect UTC time because it is controlled by “global operations” in the BIPM.
GPS time, which would be UTC’s competitor to atomic clocks, is controlled by the US military “without global oversight”, Levine said.
The solution would be to allow the difference between the rotation of the earth and the atomic time to make one minute.
It’s hard to say exactly how long that would take, but Levine estimated anywhere between 50 and 100 years.
Instead of gradually adding to the clocks, Levine proposed a “smear type”, in which the last minute of the day lasts two minutes.
“The advance of the clock slows down, but it does not stop,” he said.
© Agence France-Presse
