Science & Technology



This new atomic clock is so exact, it could be used to detect dark matter

Deborah Netburn, Los Angeles Times on

Published in Science & Technology News

Scientists have invented a new clock that keeps time more precisely than any that have come before.

The clock is so accurate that it won't gain or lose more than one second in 14 billion years -- roughly the age of the cosmos. Its ticking rate is so stable that it varies by only 0.000000000000000032 percent over the course of a single day.

That level of exactitude is not really necessary for those of us who rely on clocks to get us to a doctor's appointment on time, or to know when to meet up with friends.

But keeping time is just the beginning. This new clock is so exact that it could be used to detect dark matter, measure the gravitational waves that ripple across the universe, and determine the exact shape of Earth's gravitational field with unprecedented precision.

Indeed, these hyper-accurate clocks can help scientists better probe the mysteries of the cosmos, experts said.

"It turns out that if you have all these digits of precision for making a measurement, it can give you a microscope onto our very universe," said physicist Andrew Ludlow of the National Institute of Standards and Technology in Boulder, Colo. Ludlow led the work that produced the new clock, which was described this week in the journal Nature.

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Since the 1960s, time has been measured by so-called atomic clocks that use the natural oscillations of a cesium atom as a pendulum. Think of it as a watch with a hand that ticks just over 9 billion times per second.

The optical lattice clock Ludlow and his colleagues developed measures the much faster oscillations of a ytterbium atom. Its atomic pendulum swings about 10,000 times faster, at a speed of 500 trillion times per second.

"Cesium is a beautiful atomic system, but we have reached the basic limits of how good it can be," Ludlow said. "Ytterbium can break down time into much finer intervals, enhancing the precision with which you can measure it."

Optical lattice clocks have been around for only 15 years, and they are still in the development stage, Ludlow said. Scientists continue to tinker with them, gradually increasing their accuracy with each new adjustment.


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