a French physicist, best known for measuring the speed of light in the namesake Fizeau experiment. Following suggestions by François Arago, Léon Foucault and Fizeau collaborated in a series of investigations on the interference of light and heat. In 1848, he predicted the redshifting of electromagnetic waves. In 1849, Fizeau calculated a value for the speed of light to a better precision than the previous value determined by Ole Christensen Romer in 1676. He used a beam of light reflected from a mirror 8 kilometers away. The beam passed through the gaps between teeth of a rapidly rotating wheel. The speed of the wheel was increased until the returning light passed through the next gap and could be seen.
