Japan clocks keep time for 16 billion years

February 23, 2015
'Cryogenic optical lattice clocks' are not pretty—they look more like giant stripped-down desktop computers than ordinary wall clocks—but they are so precise that current technology cannot even measure them

Japanese researchers have built a pair of clocks which they say are so accurate they will lose a second only every 16 billion years—longer than the Earth has been around.

"Cryogenic clocks" are not pretty—they look more like giant stripped-down desktop computers than ordinary wall clocks—but they are so precise that current technology cannot even measure them.

The research team led by Hidetoshi Katori, a professor at the University of Tokyo, believes it has taken the technology way beyond the that are currently used to define the "second".

The new clock uses special lasers to trap strontium atoms in tiny grid-like structures, according to the team, which published the study this month in the journal Nature Photonics.

It then measures the frequency of the vibration of the atoms, using them like "the atomic pendulum," according to the study.

The system is so delicate that it must operate in a cold environment, around -180 Celsius (-292 Fahrenheit), to reduce the impact of the surrounding electromagnetic waves and to maintain the machine's accuracy, the team said.

Researchers connected the two clocks for a month, and estimated that it would take some 16 billion years for them to develop a one-second gap.

That is significantly more accurate than the caesium atom clock, used to define "one second", which can develop a one second error every 30 million years, they said.

The technology could be applied to satellite-based global positioning systems and communications networks, while also serving as a foundation for various precision technologies, the team said in a statement.

"Through improved precision, we hold high hopes for accelerated discussions on redefinition of the 'second'," the statement said.

Explore further: A centimeter of time: Cryogenic clocks pave the way to new measurements

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tadchem
5 / 5 (1) Feb 23, 2015
My dad used to tell me "A man with two clocks can never be certain what time it is." I'll bet if you placed one above the other (establishing a differential in the gravitational field) you could tell pretty quickly that they were keeping time at different rates. At that point the question becomes "Which one is right?"
ab3a
5 / 5 (1) Feb 23, 2015
Tadchem, it occurs to me that if the clocks are that good, one could measure gravitational fields with quite a bit of precision.
RobertKarlStonjek
5 / 5 (1) Feb 23, 2015
Japanese researchers have built a pair of clocks which they say are so accurate they will lose a second only every 16 billion years..


No doubt we'll have more accurate clocks before the need to add a leap second arises...
OceanDeep
5 / 5 (2) Feb 23, 2015
Last one out of the solar system, don't forget to take the clocks with you!!
ermesy
5 / 5 (4) Feb 24, 2015
Tadchem, they'd both be right in their respective frames of reference. Remember there is no such thing as absolute time.
antialias_physorg
5 / 5 (2) Feb 24, 2015
At that point the question becomes "Which one is right?"

Both are right. Time isn't a fixed coordinate. It's called spacetime not 'space and time' for a reason.

The point of these clocks is not to measure what time it is, which is (see above) a pointless question.
The point, however, is to put them in two different situations and see the differential that occurs (e.g. put them in the path of a gravity wave. Or use them for satellite positioning as the article suggests). If you know that the clocks are in sync when they are in the same position (and stably so) then you can be sure that the difference due to the experimental setup is only due to the thing you want to measure.
The better the clocks the lower your error bars on your measurements.
antigoracle
1 / 5 (1) Feb 24, 2015
put them in the path of a gravity wave

They would, if they could find one.
antialias_physorg
5 / 5 (1) Feb 25, 2015
They would, if they could find one.

Well, that's the point, isn't it? To get a measurement device that is adequately sensitive to tell us whether they exist or not.

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