Can't Beat These New Clocks

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Atomic clocks are already the most accurate timepieces in existence, typically losing or gaining a second every 100 million years or so. Now, researchers at the National Institute of Standards and Technology have built a pair of atomic clocks 10 times as precise as their predecessors.

Regular atomic clocks use radio waves to measure the oscillations of cesium atoms, which are far more precise than, say, the swingings of a pendulum. The researchers achieved even greater stability by using lasers that simultaneously trap and measure about 10,000 super-cooled ytterbium atoms to make a so-called optical lattice clock (like the one built this year by researchers at the Paris Observatory). The process yields clock ticks that are stable within less than two parts in one quintillion (1 followed by 18 zeros), meaning that if there were a variation in the clocks' ticking, it would show up at about the 18th decimal place.

"We've seen better stability of the clock than has ever been demonstrated by roughly a factor of 10," said Andrew Ludlow, a physicist at the science institute and an author of the study, which was published in Science.

The scientists made two clocks to test them against each other.

Practical applications for the clocks could extend well beyond timekeeping. Because they are precise enough to show the slightest effect that gravity would have on the oscillation of their atoms, they could be used to test gravitational theories, including Einstein's. Atomic clocks are integral to global positioning systems, which rely on extreme accuracy in timing. 

science

This article originally appeared in The New York Times.


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