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Atomic clocks define the standard second using caesium atoms
One second equals over nine billion transition periods of caesium-133 radiation
The fundamental International System second is defined using quantum energy transitions in caesium-133 atoms. Specifically, one second is the duration of over nine billion cycles of microwave radiation corresponding to transition between hyper-fine ground states. Atomic clocks utilizing this principle lose less than one second every hundred million years.
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Tags: measurement, time, atomic clock
Atomic clocks define the standard second using caesium atoms: the short answers
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- One second equals over nine billion transition periods of caesium-133 radiation. The figure is taken from NIST, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
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