OSA | Living History

A strontium-ion optical clock, National Physical Laboratory, UK.

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Optical Clock

Atomic clocks based on the elements strontium and ytterbium may prove even more precise than cesium clocks, considered the most accurate time-keepers.

Precise time is especially important for GPS, radio astronomy, financial transactions and identifying changes in fundamental constants. (Photo: National Physical Laboratory)

(Courtesy of National Physical Laboratory)