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How Long Is One Second, Really?


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 Physics   |   Psychology   |   Science
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Do we really know how long a second is? The science behind how time is actually measured may prove you wrong.

Who Came Up With Days, Hours, Minutes and Seconds? -
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Scientists want to change the way a second is defined
"A new optical clock ticks so consistently that if it had started at the dawn of the universe, it would have lost less than two minutes"

How does one arrive at the exact number of cycles of radiation a cesium-133 atom makes in order to define one second?
"When the cesium second was defined in 1967, it was based on a measurement of the number of cycles of the radiation from a particular cesium-133 transition with reference to the second commonly used in civilian timekeeping, which at that time was based on astronomical observations."

How Atomic Clocks Work
"In the United States, the standard of time is regulated by the US Naval Observatory's Master Clock (USNO), the official source of time for the Department of Defense. The effects of these mechanisms are felt by all of us in the f­orm of alarm clocks, computers, answering machines and meeting schedules."

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