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Time to skip leap seconds?

By Jim Boulden
CNN Correspondent


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GREENWICH, England (CNN) -- Remember the Y2K scare, when it was feared that computers couldn't read dates after 1999?

Now there is a growing concern that computer software can't handle the addition of leap seconds when clocks are continually adjusted.

Once upon a time, the world got along quite happily with local time, based on the Earth's rotation and its movement around the Sun.

Then international shipping forced the need for a universal clock to start somewhere, so Greenwich Mean Time -- GMT -- was born near London in 1884.

Greenwich is still where the Prime Meridian exists -- the line that separates the Eastern Hemisphere from the Western Hemisphere.

But few people officially use GMT anymore. It died in the 1970s, when governments adopted Coordinated Universal Time, or UTC.

The only problem with UTC is that it's too accurate -- and the unpredictable Earth won't play along.

"When you get to the milliseconds, you run into the major problem -- that the great timekeeper of the universe, or at least so we thought, in other words the rotation of the Earth, isn't accurate to the millisecond level," says Robin Catchpole of the Greenwich Royal Observatory.

When the Earth slows down, scientists add leap seconds to our clocks. There have been 22 such changes in last 30 years.

But satellite phones, computers, lasers and almost anything with a computer chip doesn't add these leap seconds, unless someone re-writes the software each time. So now, many such devices are running behind our watches.

"You might have a financial transaction being timed at a resolution at better than one second," says John Laverty of the National Physical Laboratory.

"And you get some kind of trade that could be confused because somebody would think they are ahead, and they were behind. So, its because of that theoretical possibility that some people think it may be better to change (the way we tell time)."

GPS
Handheld Global Positioning System (GPS) units are on a different clock than Universal Coordinated Time.

Forget leap seconds, say some few academics, and let our descendants sort it out later.

That way, at least for now, computers, satellite phones, atomic clocks and people would all be on the same time -- although we will all be out of synch with the Earth itself.

Says Catchpole: "We will be a second out after a few years, and you know after a hundred years or so we might be 30 seconds out of kilter with the actual rotation of the Earth."


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