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[Chicago Astronomer - Astro Joe]

Why the US wants to end link between time and sun

Time to change the way we measure time, according to a U.S. government proposal that businesses favor, astronomers abominate and Britain sees as a threat to its venerable standard, Greenwich Mean Time.

Word of the U.S. proposal, made secretly to a United Nations body, began leaking to scientists earlier this month. The plan would simplify the world's timekeeping by making each day last exactly 24 hours. Right now, that's not always the case.

Because the moon's gravity has been slowing down the Earth, it takes slightly longer than 24 hours for the world to rotate completely on its axis. The difference is tiny, but every few years a group that helps regulate global timekeeping, the International Earth Rotation and Reference Systems Service, tells governments, telecom companies, satellite operators and others to add in an extra second to all clocks to keep them in sync. The adjustment is made on New Year's Eve or the last day of June.

But adding these ad hoc "leap seconds" -- the last one was tacked on in 1998 -- can be a big hassle for computers operating with software programs that never allowed for a 61-second minute, leading to glitches when the extra second passes. "It's a huge deal," said John Yuzdepski, an executive at Symmetricom Inc., of San Jose, Calif., which makes ultraprecise clocks for telecommunications, space and military use.

More here: www.post-gazette.com/pg/05210/545823.stm
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I'm saving my seconds for future use.

[Centaur]

Interesting - thanks for the post. The leap-second system could not go on forever. As a celestial mechanic who requires a proper time argument for his software, I would easily be able to make the adjustment if a new system were implemented that continuously accounts for changes in the rotational speed of the Earth. BTW, in recent years that speed has actually been increasing, although over the long-run it has been decreasing.

[Maddad]

It's supposed to be a huge deal, but in truth it's only a software deal. A tiny bit of extra code and the problem goes away.

I read a science fiction book once in which some people traveled to the future, fifty million years I think. By then the Earth had twenty-five hours in a day from the drag by the Moon. They still used the 24 hour clock, but added a leap hour every night that they called the witching hour.

[Chicago Astronomer - Astro Joe]

I understand that the Moon is also orbiting away from the Earth as well.

So, as in the sci-fi book you were reading...would the drag be as great, considering the extended distance, as to slow the rotation of the Earth by an hour?

If so, I'm resetting all my clocks now.

[Maddad]

No, the drag would be less if the distance were greater because drag is a function of gravity, and that decreases with increasing distance. The drag during a year now is more than the drag during a year fifty million years in the future.