Be vewy, vewy, caweful wif cesium.
Posted on 02/18/2006 1:38:11 PM PST by Loyalist
An Ottawa researcher says it's about time the world had a better clock, and he is spending most of his waking hours creating it.
He's working with the National Research Council of Canada to build the world's most accurate clock -- a cesium fountain clock, which would be 100 times more accurate.
"We have to be very, very careful in building it, because it has to be perfect," he says.
He says the clock would better meet the demands of scientists around the world who need such precision for their work.
Marmet works for the National Research Council's Institute for National Measurement Standards. Surrounded by atomic clocks at work, he never wears a watch.
"Why should I wear a watch?" says Marmet. "It's not the right time anyway."
Most atomic clocks work by measuring the oscillations of cesium atoms, which always move at the same speed. But cesium atoms are tough to measure because they move so quickly. The best atomic clocks can only measure cesium atoms for a split second.
That's not good enough for Marmet and his team, which includes University of Ottawa physics professor Christian Gigault.
While it may seem trivial to measure time by fractions of nanoseconds, Marmet says such
accuracy has useful benefits. He says the blackout that struck Ontario and parts of the U.S. in August 2003 could have been prevented if the atomic clocks were as precise as the fountain clock. If technicians could pinpoint the exact fraction of a second that a circuit failed on the power grid, he says, they'd be able to narrow in on the problem areas more quickly.
The fountain clock would also be useful in global positioning systems, satellites and other devices that increasingly depend on greater degrees of precision to operate.
A standard atomic clock shoots cesium atoms through a horizontal chamber. As the atoms zip by, sensors briefly scan them before they eventually spew out of the chamber.
The fountain clock, however, uses lasers to first cool the atoms, reducing the speed at which they travel. The cooled atoms are then shot upwards into the fountain clock's chamber, so sensors have more time to measure them.
Think of an atomic clock like a tuning fork. The longer you listen to a tuning fork, the more time you have to get a perfect pitch. So, the longer you monitor the oscillations of cesium atoms, the more time you will have to get a more precise reading.
Because the fountain clock's chamber stands upright, gravity pulls the atoms back down into the chamber, where the clock's sensors scan them a second time, producing a far more precise reading. "It's like making the master tuning fork that will tune all the orchestras in Canada," says Gigault.
The fountain clock takes up most of a lab at the NRC. A big, black snooker table-sized box covered with lenses, lasers and other gadgets floats a few feet from the floor, held up by high-pressure air jets. This is done so even the slightest ground vibration doesn't affect the clock.
Next to the table sits a four-metre silver box, which scans the atoms as they pass through.
The NRC sends the official time from its standard atomic clocks to the International Bureau of Weights and Measures in Paris. The French organization gathers official times from countries around the world and takes a weighted average to produce the planet's official time. The NRC has been working on the fountain clock for 13 years, at a cost of between $500,000 and $600,000, not including staff salaries.
© The Edmonton Journal 2006
I'm always running late for work too. Where can I get a new cesium alarm clock?
Be vewy, vewy, caweful wif cesium.
BUMP!
100 times more accurate than WHAT?
Yes, compared to what? And . . . how do lasers "cool" the atoms down? Is this lousy reporting? hmmmmmm
Being retired I was thrilled to threw all my clocks away. When the Sun is up, it's day time. When it's dark out, it's night. :-)
Well, if this fantastic clock is off by 1 trillionth of a second, and it is EXACTLY correct today, it will not be EXACTLY correct again for 1 trillion seconds, or 16,666,666,666.67 minutes, or 277,777,777.78 hours, or 11,574,074.07 days, or 31,688.09 years, or 316.88 centuries.
Heck, I ran over my $9.95 Timex with my truck last week, and I'll be darned if it isn't EXACTLY correct two times a day now!!!
Do I have a great memory, or what: http://www.nist.gov/public_affairs/releases/miniclock.htm
Doesn't exactly tell you where or when to buy it, but it may be coming to a swatch near you.
From Yellow Submarine:
"Maybe time's on strike."
"What for?"
"Shorter hours..."
Who was it that split the second, anyway?
One second was defined originally as 1/86,400 of the time between local noon events for the planet Earth which is IIRC about about 1/86,637 of its rotational period. Although atomic clocks have wonderful consistency, they don't quite match the original standard. If a conventional atomic clock and this one were both used to time 3,155,673,600 seconds when the Sun was directly south of Greenwich Observatory on February 20, 2006, I think the difference between when they finished and when the Sun passed south of Greenwich on February 20, 2106 would be greater than the difference between them.
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