The best clock in the world has no hands, no pendulum, no face or digital display. It’s a jumble of lasers, wires and strontium atoms in Jun Ye’s lab at the National Institute of Standards and Technology (NIST) in Boulder, Colo. He keeps it cooled to about three millionths of a degree above absolute zero.
The clock, described by Ye in the Feb. 6 Nature, is so precise that had it begun ticking when Earth formed 4.5 billion years ago, it would not yet have gained or lost a second. Over that span, a Swiss quartz watch would stray at least a few thousand years.
Ye’s atomic, or optical, clock is impressive, but it’s just one step toward an ambitious timekeeping goal. He and his colleagues at JILA, a joint institute of NIST and the University of Colorado Boulder, envision 10 or more atomic clocks, installed in satellites and international labs, and intricately connected to form the equivalent of one global superclock. Whenever Ye checked the time with the atom-probing laser in his Colorado laboratory, his clock would be connected with every other clock on the network — instantaneously, regardless of distance — and deliver a reading hundreds of times as accurate as those produced by today’s atomic clocks.
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