[skipwords]UPDATED, JAN. 19: The decision to keep or abandon the "leap second" has been pushed back for another three years, the BBC reports. Delegates at the U.N.'s International Telecommunication Union reportedly couldn't reach a consensus on the issue, so they have punted to a future meeting in 2015. The next leap second is currently scheduled to take place June 30.
Unlike leap years — which deal with Earth's 365.24-day orbit by adding an extra day to the calendar every four years — leap seconds exist because Earth's rotation periodically changes speeds, which makes it an inherently inaccurate way to keep track of the time.
Leap seconds were introduced 40 years ago in response to atomic clocks, which are the most accurate timepieces known. Since atomic clocks rely on atomic radiation rather than sunlight to tell time, they inevitably outpace the gradually lengthening solar day. A leap second, therefore, simply "pauses" all atomic clocks whenever they start getting too far ahead.
The U.S. and several other U.N. countries support scrapping the leap second, since it handicaps our most precise clocks to accomodate our relatively imprecise planet. "This would be an important decision because the problem of introducing the leap second would disappear, and we would have a more steady time than we have today," ITU official Vincent Meens tells the Associated Press.
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According to Judah Levine, a physicist at the U.S. National Institute of Standards and Technology, "most of the people who operate time services favor discontinuing leap seconds," including operators of cellphone networks, financial markets, airports and spaceports. "The main problem is that the leap second is usually implemented by stopping the clock for one second," he tells the AP. "However, the world doesn't stop."
Not everyone wants to nix leap seconds, though, which became clear during this week's ITU meeting in Geneva. China warns the move could make it hard for astronomers to compare long-term data, while the U.K. says it could render Greenwich Mean Time (GMT) meaningless. Canada also has reservations, and even some U.S. officials seem hesitant. "Leap seconds are an inconvenience to the telecommunications people, but there are many other users of time who should be considered," says Ken Seidelmann of the U.S. Naval Observatory.
Without the leap second, atomic clocks would outpace the solar day by about 90 seconds per century, or roughly one hour every 4,000 years. And after a few dozen millennia, that means atomic clocks would say it's afternoon before the sun has risen.
"We have to have some means of making a correction, but at the moment no one knows how that's going to be done" if leap seconds are eventually abolished, Peter Whibberley of the U.K.'s National Physical Laboratory tells CNN.
But, speaking to the BBC on Thursday, Whibberley expressed relief the decision is now delayed. "This result achieves the U.K.'s aims of securing much broader debate and understanding of the consequences of ending the link between UTC [Coordinated Universal Time] and solar time before a final decision is taken," he says. Delegates still plan to discuss the issue at another ITU meeting next week, the AP reports, but no formal decision is expected until 2015.[/skipwords]
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