Atomic Scientists Set 'Doomsday Clock'
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For many years, cesium atomic clocks have been reliably keeping time around the world. But the future belongs to even more accurate clocks: optical atomic clocks. In a few years' time, they could change the definition of the base unit second in the International System of Units (SI).
USA TODAY asked Alexandra Bell, the president and CEO of the Bulletin of the Atomic Scientists, a few questions about the Doomsday Clock.