Science: Slowdown at Sunrise

Slowdown at Sunrise Governed by the natural rhythm of an isotope of the cesium atom—which vibrates exactly 9,192,631,770 times per second—the atomic clock has long been considered man's most accurate timekeeper. Calculated to gain or lose less than a second over a period of 6,000 years, it was adopted by the 1967 General Conference of Weights and Measures as the international time standard. Despite those impressive credentials, which are accepted by most scientists, the reliability of the clock has now been questioned by two experimenters at the U.S. Naval Research Laboratory.

When the sun rises, Physicists Dror...

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