WHAT:
Caesium-133 Primary Standard Atomic Clock
WHERE:
NPL, Hampton Rd, Teddington, TW11 0LW, UK
LOCATION:
WHEN:
1955
WHO:
Louis Essen
DETAILS:
In 1955, the National Physical Laboratory built the world’s first caesium‑133 atomic clock, designed by physicist Louis Essen. This groundbreaking achievement provided an unprecedented level of accuracy in measuring time and became the basis for defining the international standard second. The clock marked a turning point in science and technology, influencing fields such as global navigation, telecommunications, and space exploration. NPL’s work on the atomic clock remains one of its most celebrated contributions, shaping the way time is measured worldwide.
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