Sec­ond thoughts: Is a tiny ad­di­tion in time too much?

The China Post - - LIFE - BY PAS­CALE MOL­LARD

Ques­tion: When is a minute not a minute?

The an­swer: At 2359 Green­wich Mean Time (GMT) on June 30, when the world will ex­pe­ri­ence a minute that will last 61 sec­onds.

The rea­son for the weird event is some­thing called the leap sec­ond.

That’s when time­keep­ers ad­just high-pre­ci­sion clocks so that they are in sync with Earth’s ro­ta­tion, which is af­fected by the grav­i­ta­tional tug of the Sun and the Moon.

Few of the planet’s 7.25 bil­lion peo­ple are likely to be aware of the change ... and even fewer will have set plans for how they will spend the ex­tra mo­ment.

But for horologists, the ad­di­tional sec­ond is a big deal, and there is a wran­gle as to whether it is vi­tal or should be scrapped.

“There is a down­side,” ad­mits Daniel Gam­bis, di­rec­tor of the Ser­vice of the Ro­ta­tion of the Earth — the po­et­i­cally named branch of the In­ter­na­tional Earth Ro­ta­tion and Ref­er­ence Sys­tems Ser­vice (IERS), in charge of say­ing when the sec­ond should be added.

To be clear, the leap sec­ond is not some­thing that needs to be added to that old clock on your man­tel­piece.

In­stead, its im­por­tance is for su­per-duper time­pieces, es­pe­cially those us­ing the fre­quency of atoms as their tick-tock mech­a­nism.

At the top of the atomic-clock range are “op­ti­cal lat­tices” us­ing stron­tium atoms, the latest ex­am­ple of which, un­veiled in April, is ac­cu­rate to 15 bil­lion years — longer than the Uni­verse has ex­isted.

Out­side the lab, ce­sium and ru- bid­ium clocks are the work­horses of Global Po­si­tion­ing Sys­tem (GPS) satel­lites, which have to send syn­chro­nized sig­nals so that sat-nav re­ceivers can tri­an­gu­late their po­si­tion on Earth.

On Earth, big-data com­put­ers may be less manic than atomic clocks but still need highly pre­cise in­ter­nal timers.

The In­ter­net, for in­stance, sends data around the world in tiny pack­ets that are then stitched to­gether in mi­cro-sec­onds. Some al­go­rithms in fi­nan­cial trad­ing count on gain­ing a tiny slice of a sec­ond over ri­vals to make a profit.

There have been 25 oc­ca­sions since 1971 when the leap sec­ond was added in an ef­fort to sim­plify Co­or­di­nated Uni­ver­sal Time (UTC), the of­fi­cial moniker for GMT.

Time to Go?

But over the last 15 years, a de- bate has in­ten­si­fied about whether the change should be made, given the has­sle.

“The ar­gu­ment of crit­ics is that it’s be­come more and more dif­fi­cult to man­age these days, as so much equip­ment has in­ter­nal clocks,” says Roland Le­houcq of France’s Atomic Energy Com­mis­sion (CEA).

“The prob­lem is syn­chro­niza­tion be­tween com­put­ers. They do sort things out, but some­times it can take sev­eral days.”

The last mod­i­fi­ca­tion, on June 30, 2012, was dis­rup­tive for many In­ter­net servers — the online reser­va­tion sys­tem for the Aus­tralian air­line Qan­tas “went down for sev­eral hours,” says Gam­bis.

“It’s time to get rid of the leap sec­ond. It causes com­pli­ca­tions and bugs,” ar­gues Se­bastien Bize, a spe­cial­ist in atomic clocks at the SYRTE Lab­o­ra­tory — it means Time-Space Ref­er­ence Sys­tem — at the Paris Ob­ser­va­tory.

Gam­bis de­fends the change on the grounds of prin­ci­ple.

“Should Man be the ser­vant of tech­nol­ogy? Or should tech­nol­ogy be the ser­vant of Man?” he asks rhetor­i­cally.

Af­ter all, if the world got rid of the leap sec­ond, time as counted by mankind would no longer be cou­pled to the ex­act ro­ta­tion of the planet it lives on.

“That would mean in 2000 years, there would be an hour’s dif­fer­ence be­tween UTC and the time it takes for the Earth to com­plete one com­plete turn,” notes Gam­bis.

“It would mean that, on a scale of tens of thou­sands of years, peo­ple will be hav­ing their break­fast at two o’clock in the morn­ing.”


Michel Ab­grall, head of na­tional ref­er­ence ser­vice time at the “Lab­o­ra­toire Na­tional de Metrolo­gie et d’Es­sais” (LNE -SYRTE, Time-Space Ref­er­ence Sys­tems), part of the Paris Ob­ser­va­tory re­spon­si­ble for de­vel­op­ing ref­er­ence stan­dards in the time­fre­quency, mon­i­tors a bank of equip­ment on Fri­day, June 12.

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