The first accurate atomic clock was built in 1955.
This led to the internationally agreed definition of
the second being based on atomic time.

Under the International System of Units, the
second is currently defined as the duration of 9 192
631 770 periods of the radiation corresponding to the
transition between the two hyperfine levels of the
ground state of the caesium atom.

Feel the rhythm of the Universe's symphony with
the Atomic Clock screensaver and always know the
accurate time!

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