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"It is better to be drunk with loss and to beat the ground, than to let the deeper things gradually escape."

- I. Compton-Burnett, letter to Francis King (1969)

"Cynical realism – it is the intelligent man’s best excuse for doing nothing in an intolerable situation."

- Aldous Huxley, "Time Must Have a Stop"

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Friday, 29 July 2005

Topic: Science

Basic Science: Counting the Seconds, or Not

Much has been said, again and again, about the "ugly American" trying to make the whole world over to be just like us, and offending others who don't much want to go along - but this?

Why the U.S. Wants To End the Link Between Time and Sun
Astronomers Say Wait a Sec, Sundials Would Be Passé; Mean Blow to Greenwich
Keith J. Winstein, The Wall Street Journal, July 29, 2005; Page A1

Okay, it was on the front page of the newspaper-of-record for the captains of industry here in America, but is it news or, perhaps, just a giggle?

What's the deal?

It seems the WSJ has a scoop here, that we made a secret proposal at the UN and the word is leaking out -
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.
Ah! It's these ad hoc "leap seconds" that are the problem. The last one was added in 1998 and we may be due again. And it seems this is going to create no end of problems for a subset of computers that cannot tolerate even one 61-second minute. And we are told of Symmetricom, an outfit out here in San Jose, that makes really, really, really precise clocks for telecommunications and the military – and for the space program. One of their executives is quoted as saying this is a "huge deal."

And it's not just the guys up north. It seems at the start of 1998, the last time an extra second was added, Associated Press Radio crashed - or at least started sending out the wrong tapes. The year before the Russian global positioning system (Glonass) was down for twenty hours when they uploaded an extra second and everything went bad. And we're told that in 2003 a leap-second bug made GPS receivers from Motorola briefly show customers the time as half past 62 o'clock - and no extra second was even added.

Well, it's not Y2K but it is a problem.
"A lot of people encounter problems with their software going over a leap second," said Dennis D. McCarthy, who drafted the U.S. leap-second proposal while serving as the Navy's "Director of Time." Because of these problems, the U.S. government last year quietly proposed abolishing leap seconds to the International Telecommunications Union (ITU), the U.N. body that tells the Earth Rotation Service how to keep time.

"Safety of life is an issue," said William Klepczynski, a senior analyst at the State Department in favor of the U.S. proposal, who asserts that programmers who ignore the need to add leap seconds present a "risk to air travel in the future" because a glitch might shut down traffic-control systems.

Eliminating leap seconds will make sextants and sundials slowly become inaccurate, but supporters say that's OK now that the satellite-supported GPS can give exact longitude and latitude bearings to anyone with a receiver. Sailors "don't navigate with the stars any longer," said Dr. McCarthy.
So what's the problem? (And our Navy has a "Director of Time?" Cool.)

One problem is the French, specifically the Earth Rotation Service's leap-second head, one Daniel Gambis, of the Paris Observatory. To wit: "As an astronomer, I think time should follow the Earth."

Don't we all?

He calls the American effort a "coup de force," and an "intrusion on the scientific dialogue." And he say ninety percent of the subscribers to his service are quite happy with the extra seconds now and then. And some of them?
"We should not so blithely discard the ties between our clocks and the rotation of the Earth," wrote Rob Seaman, a programmer at the National Optical Astronomy Observatories in Tucson, Arizona. Jean Meeus, an influential Belgian astronomer, called the U.S. proposal "a disaster for classical astronomy" and a "dirty trick."
A dirty trick?

Well, ask the British about this. They want none of it. From 1884 to 1961 the world set its official clocks to Greenwich Mean Time, based on the actual rise and set of the stars as seen from the Royal Observatory in Greenwich, just outside London. Well, now everyone uses Coordinated Universal Time - atomic clocks and all that - and everyone agreed to insert leap seconds in order to keep the official time within one second of the old Greenwich time.


It seems BBC and Big Ben now follow Coordinated Universal Time, but Parliament has just refused to change the country's official standard away from Greenwich time. It's a matter of national pride, after all. But if getting rid of the "leap seconds" may be necessary, so much for GMT - it slowly becomes just another quaint and utterly useless British custom.

But the WSJ reports that Britain's science minister, Lord Sainsbury of Turville, decided in April, during Tony Blair's re-election campaign, to oppose the U.S. proposal. "It could have been used to attack the government," said Peter Whibberley, a scientist who represents Britain to the ITU. "People regard GMT with some sensitivity," he said. "It gets tied up with the general anti-Europe feeling."

Many of us missed all that in the reports on the recent British elections.

But you see the real problem with dropping "leap seconds," don't you? Do that and the sun starts rising later and later by the clock - a few seconds later each decade.

But we have an answer! We're proposing adding a "leap hour" every five hundred years or so. After all, the Earth's rotation is expected to slow down further. You have to do something. It seems Ronald Beard of the Naval Research Laboratory - our man who chairs the ITU special committee on leap seconds (and favors their abolishment) - thinks this is no big deal. Think of the shift to Daylight Saving Time each year. "It's not like someone's going to be going to school at four in the afternoon or something."

But this whole "abolish leap seconds" proposal is, as noted, secret. The WSJ couldn't get any top US officials to comment. They called the head of our delegation - D. Wayne Hanson of the National Institute of Standards and Technology - but he won't talk. Through a spokeswoman, he said that our proposal "is a private matter internal to the ITU and not for public discussion."

Still the astronomers are ticked - do the extra seconds get dropped and do the upgrades to the telescopes have to be made - or not? They want some openness here.

Well, maybe it just has to be done, if only to coordinate air traffic control. That's what our State Department is saying (see above). It's a matter of safety. (But don't forget the military and space programs.)

The WSJ ends with this:
Deep down, though, the opposition is more about philosophy than cost. Should the convenience of lazy computer programmers triumph over the rising of the sun? To the government, which worries about safety more than astronomy, the answer is yes.
But then there's the one astronomer they quote: "Time has basically always really meant what you measure when you put a stick in the ground and look at its shadow."

Really? Not these days.

Posted by Alan at 20:26 PDT | Post Comment | Permalink
Updated: Friday, 29 July 2005 20:29 PDT home

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