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The Future of Leap Seconds
@10u8 writes "Since 1972 precision clocks around the world have ticked using atomic seconds, but earth rotation is slowing down. Leap seconds have been inserted in order to keep noon happening at noon, but they upset some timekeepers. Recent discussions have considered
discontinuing leap seconds in UTC, and a colloquium in Torino next month will present results. It is a matter of international significance."
And why do we care?
Read the article!
It's important for systems programmers, and lots of folks here are at least systems programming fanboys.
It's important for navigation. Yeah, that includes your GPS toys.
It's important for a number of scientific disciplines, including a number of subdisciplines of radio astronomy.
It's also really interesting that the change in the Earth's rotation can't yet be predicted with enough accuracy to set a schedule in advance for adding leap seconds, but must be measured. This is relatively prosaic stuff that's nonetheless at the limits of our current understanding. Doesn't anyone get excited or curious about science anymore?
And just think, if no leap seconds were added since 1972, you'd be having your Noon Lunch at 11:59:38!
:)
Oh the horror...
Accuracy isn't everything...
"Can of worms? The can is open... the worms are everywhere."
The concept of leap years is because the ratio of the length of a year divided by the length of an earth day is not an iteger. No calendar can get around that fact. You either add intercalation days whenever the remainders of your divisions exceed 1, or you keep track of huge numbers and cycles that greatly complicate your timekeeping.
The Julian roman calendar did suck because they didn't get the ratios quite right and it drifted. (The Gregorian calendar fixed this for all practical purposes.) However, prior to Julius Caesar, it sucked even more because there was no mathematical formula. Instead, priests were supposed to observe the sun each year and decide when leap days were needed.
The priests were also involved in politics, so they chose to shorten political terms more often than not by omitting leap days. IIRC, by the time the Julian calendar was instituted, the Romans were off by several months due to these partisan shenanigans.
The stated problem with leap seconds is that some software gets confused by them. Guess what? That same software probably gets confused if the time zone changes, or when it moves into daylight savings time.
The Right Way to solve this problem is for computers to work with TAI internally, and treat the difference introduced by leap seconds as part of the time zone, for human consumption only. Instead of defining PST to be UTC - 08:00, define PST = TAI - 08:00:22.
Computers can keep their straightforward time system, humans can keep our astronomically synchronized system. No need to lose either of those qualities.
Tarsnap: Online backups for the truly paranoid
With a manned mission to Mars possibly less than 20 years away, shouldn't we start looking at timekeeping systems that aren't tied to this rock?