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Australia is ready to vote to ditch the leap second at upcoming Paris summit Australia is ready to vote to ditch the leap second at upcoming Paris summit

Australia is ready to vote to ditch the leap second at upcoming Paris summit

Zach Blass

Back in August we covered the idea of a “negative leap second“, in which, due to the record short day lengths a backward leap second may need to be instituted to reconcile time. At the time I thought the subject was done and dusted, as scientists did not believe any alarms needed to be rang just yet. But the leap second has once again made headlines this month, with the Sydney Morning Herald reporting that Australia is primed to vote to ditch the leap second at an upcoming summit in Paris.

Image: Sydney Morning Herald

What challenges do leap seconds pose?

Michael Wouters with Australia’s atomic clock. Image: Ben Rushton

Most people are familiar with the idea of a leap year, which occurs once every four years. But leap seconds are much more inconsistent and on-demand versus scheduled. Since 1972, there have been 27 instances of a leap second being added. While such a small measurement of time, at least from the perspective of the human experience, would seem little to fuss over, from a technology perspective it can pose serious challenges in a world ever more interconnected by computers. In 2012, for example, the social news and discussion platform Reddit went down due to an introduced leap second – leaving the Reddit team scrambling to restore the site for 30 or 40 minutes. Four years later, the last time a leap second was added, major DNS platform Cloudfare went down for 90 minutes due to a picked up negative value. This meant that for 90 minutes, the web properties of a number of small businesses that utilised their hosting services went down, too.

On a larger scale, leap seconds can create even more troublesome issues. The Sydney Morning Herald explains: “The BIPM notes that global navigation satellite systems, telecommunication networks and energy transmission systems could all go down unexpectedly due to the addition of a second.” The Herald also notes how disruptive a leap second can be for an entity like NASA . They explain: “To an organisation such as NASA, time is distance. The American space agency notes that a quartz crystal clock is not stable enough for space travel. After an hour, the best-performed quartz-based clock can be out by a billionth of a second. After six weeks, it estimates such a clock could be out by a full millisecond. The fastest hummingbirds can flap their wings about five times in a millisecond. But in space, that millisecond can equate to about 300 kilometres in distance.”

What motion is on the table at the Paris summit?

leap second
Image: Sydney Morning Herald

What Australian representatives, and others who share the same perspective, are proposing is a 100-year pause. For the next twelve years, under the proposal, additional leap seconds would be permitted. But, beginning in 2035 there would be no additional leap seconds added until 2135. This would give the scientific community a century to better reconcile atomic and astronomical time.

Major platforms such as Meta, which owns Facebook and Instagram, support such a proposal. Ahmad Byagowi, a California-based research scientist at Meta who specialises in areas including time and frequency synchronisation in large networks, explained to The Sydney Morning Herald: “For the foreseeable future, Meta engineers are supporting a larger community push to stop the future introduction of leap seconds and remain at the current level of 27, which we believe will be enough for the next millennium.” Byagowi further explained that it would take a pause of a thousand years, 10 times more than the 100 year pause of the leap second, before would be a noticeable gap between the relative position of the stars in the sky and atomic clock time.

The other concern with further leap seconds being added is that it could lead to the eventual introduction of a “negative leap second”, something Byagowi and others believe would have a much more devastating impact on technological systems than a leap second. It will be interesting to see how this vote pans out, and what effect it will have.