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Air Apparent

Ummm, don't they have that backwards?

Wired informs us that human-made clocks are now more precise than the rotation of the earth around the sun.

International Atomic Time — kept by ultraprecise clocks — is gradually out-pacing astronomical time, which is determined by our planet's rotation. (Earth's spin is slowing — what a drag.) So in 1972, the International Earth Rotation and Reference Systems Service began adding occasional leap seconds. They've done it 23 times, most recently adding an extra "one-Mississippi" on December 31, 2005.

I'm sorry, but doesn't this just mean that all the scientists agreed to a system of time that just wasn't accurate, and now they are having to fix it up?

Now there's a legacy software problem for you. Programmers just love to tell you it's all the previous programmers' fault that the software doesn't work. Now they are blaming God for making the earth rotate around the sun imprecisely?


Steve Allen

Scientists have agreed to quite a number of systems of time, each of which serves its own purpose. The question is, what do you want time to tell you? If there can be only one time, then you're in trouble automatically. The time that physical processes want is necessarily very precise yet relative to each observer, so somebody has to manage a conventional and therefore political scheme for calculating an agreeable version. The time for people who want to know when to hold an outdoor soccer game on a field without lights is far more dependent on the actions of politicians making daylight time decrees than it is on the rotation of the earth. POSIX has the mechanisms to implement both via zoneinfo, but that scheme will not work right for everyone unless the leap seconds are moved from the system time_t into the zoneinfo files, and that means getting all the rest of the time hierarchy to agree to renaming things and deciding who is in charge of what.

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