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Armand Hippolyte Louis Fizeau

1819-1896

French physicist who in 1849 was the first to measure the speed of light on Earth. Fizeau was also the first to use the Doppler principle to measure the speed of stars moving toward or away from the observer. This principle is still used quite extensively in astronomy to measure the velocity of galaxies, the motion of gas swirling into black holes, and the expansion of the universe.

Armand Hippolyte Louis Fizeau

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