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Longest measured Time Dilation

Longest measured Time Dilation
Who
US Naval Observatory
Where
Not Applicable
When
October 1971
In October 1971 four caesium atomic clocks were flown around the world after being synchronized with reference clocks at the US Naval Observatory, in order to measure the effects predicted by Einstein's Theory of Special Relativity. When flown westwards, the clocks gained 273 +/- 7 nanoseconds and, when flown eastwards, the clocks lost 59 +/- 10 nanoseconds. The difference is due to the Earth’s rotation.