Hippolyte Fizeau

Revolutionary physicist who made first terrestrial measurement of light speed

Armand Hippolyte Louis Fizeau (1819-1896) achieved what was considered impossible in 1849 - measuring light's speed on Earth's surface. Before his experiment, scientists only attempted astronomical measurements like those by Ole Rømer. Fizeau's ingenious apparatus used a rotating toothed wheel and distant mirror, calculating light velocity within 5% accuracy of modern values.

This Parisian physicist also made crucial contributions to Doppler effect understanding in light waves (1848) and took the first detailed photographs of the Sun using Daguerre's process. His Fizeau experiment (1851) demonstrating light drag in moving water directly influenced Einstein's special relativity.

What made Fizeau's work extraordinary was his ability to measure the immeasurable through mechanical ingenuity. As Albert Einstein later noted: Fizeau's experiment provided crucial confirmation for special relativity theory. His terrestrial measurement method became standard in physics laboratories worldwide, fundamentally changing experimental optics.