Well, no, actually they don’t.
I get really annoyed by the 3-5 minute difference between my computer and the time display on my office phone. But that’s just annoyance.
The real trouble comes between trying to impose digital accuracy on an analog world — or trying to make a constant (vibrational frequency of atoms, the foundation for atomic clocks) match up to a variable (the rotation of the Earth). We use atomic clocks instead of the rotation because it is a variable — over time it’s slowing down, and not even at a constant rate — but as atomic timekeeping is becoming more widespread, that discrepency is becoming more of a problem.
The problem arises because the Earth cannot keep time as accurately as modern atomic clocks, which count the steady shaking of atoms. These atomic clocks replaced the motion of the Earth as the world’s official timekeeper in 1967. The pull of the moon is gradually slowing our planet down, so every now and then our clocks are halted for a second to let it catch up.
The first of these “leap seconds” was introduced in 1972, mainly as a favour to astronomers and others who still relied on the old-style celestial time. A further 31 leap seconds have been added since, most recently on December 31 1998.
And that would be that, were it not for the fact that the precise timekeeping offered by atomic clocks is now becoming widely available – most commonly through the satellite global positioning system used for navigation. To add to the confusion, GPS uses yet another timescale.
It includes the leap seconds added until the GPS clock was set in 1980, but has ignored those added since. This means GPS time is now running 13 seconds ahead of coordinated universal time – which includes all added leap seconds and to which most clocks on Earth are set – but is some 19 seconds behind international atomic time, which is based on atomic clocks and ignores leap seconds.
If you consider how far a jet aircraft can move in 13-19 seconds, you can catch a glimpse of some of the problems.
And, of course, the Europeans are (unilaterally) going to have a different system/benchmark when they launch their own GPS system.
Naturally, the real threat is the lawyers getting involved.
“We face possible problems in the timestamping of electronic documents,” [Dennis McCarthy of the US Naval Observatory] says. This is because a leap second is usually added at the end of the day, by asking clocks to change from 23:59,59 to 23:59,60 before going on to 00:00,00. But as most clocks don’t permit the number 60, they show 23:59,59 for two seconds instead.
“I suspect it will happen eventually that someone says their 23:59,59 refers to a different 23:59,59 and lawyers will become involved,” Mr McCarthy says. This could be important for legal or financial documents detailing the sale of bonds and securities at a specific time.
The techies are looking at a simple answer — banning leap seconds. Then everything is nice and neat and simple — except for trivial matters like the real world. Not only would it throw astronomical observations for a loop, but eventually you’d have a discrepency between when the sun rises and when the almancs say it should rise. Ultimately, day and night on the clock would fail to correlate with the sun in the sky.
To stop this happening, we would need to introduce a leap hour every 700 years or so, in a similar way to how we change our clocks to account for summertime.
I suspect that worrying about what folks 700 years from now will have to do will be a non-starter for the wonks who figure this out.
(via BoingBoing)