Hippolyte Fizeau

French physicist.

His earliest work was concerned with improvements in photographic processes. 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 red shifting of electromagnetic waves. In 1849, Fizeau calculated a value for the speed of light more precise than the previous value determined by Ole Rømer in 1676. He used a beam of light reflected from a mirror eight 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.

Fizeau made the first suggestion in 1864 that the "length of a light wave be used as a length standard".

Fizeau was involved in the discovery of the Doppler effect.

In 1853, Fizeau described the use of the capacitor (sometimes called a "condenser") as a means to increase the efficiency of the induction coil. Later on, he studied the thermal expansion of solids, and applied the phenomenon of interference of light to the measurement of the dilatations of crystals. He became a member of the Académie des Sciences in 1860 and a member of the Bureau des Longitudes in 1878.

He died at Venteuil on 18 September 1896.

"Fizeau" is one of the 72 names inscribed at the base of Eiffel Tower.