The Leap Second Is No More

“There are continuing problems with positive leap seconds even after 50 years, and the concern was that the negative leap second would be much more serious because its effects had never been tested,” Levine says.

BIPM time department director Patrizia Tavella confirmed those concerns in an email to WIRED. “The probability of a negative leap second convinced us [to] set the application date in 2027,” she wrote, adding that there was added urgency following tests by an industry standards group that “showed several failures with a negative leap.”

Tavella says the group is waiting until May 20 2027 to implement it because it’s the anniversary of 1875 signing of the Metre Convention, creating BIPM, as well as Metrology Day. In other words, it’s the perfect time to mark the passing of time—or more accurately, the lack thereof.

The death of the leap second makes life easier for everyone now. “The nice fact is that we have nothing to do!” Tavella says. “Just continue to accumulate second[s] and ‘normal’ minutes of 60 seconds.”

Levine concurs, writing that “life will have one less hassle.”

But kicking the can on adding leap seconds doesn’t mean atomic time and astronomical time won’t continue to drift apart. That’s why BIPM also agreed to create a leap hour. Given how long it takes leap seconds to add up, a leap hour is millennia away. (There are, after all, 3,600 seconds in an hour.)

“We do not speak of leap hour yet,” Tavella says. “If systems rely on UTC, they have nothing to do. If they rely on UT1, they have to be able to use the information UT1-UTC which, in [the] future, will be larger than 1 second.”

In other words, not our problem, and good luck to future generations!