A. A. Michelson

Albert Abraham Michelson was an American physicist renowned for his precision in measuring light's speed. He is most famous for designing the Michelson-Morley experiment in 1887, which tested the idea of a luminiferous ether—a supposed medium through which light was thought to travel. The experiment's null result provided strong evidence that light speed is constant, regardless of Earth's motion, laying the groundwork for Einstein's theory of relativity. Michelson's meticulous techniques in interferometry profoundly advanced experimental physics, earning him the Nobel Prize in Physics in 1907.