Albert Michelson

Albert Michelson (1852-1931), German-born American physicist, known for his famous experiment to measure the velocity of the Earth through the ether, a substance that scientists believed filled the universe. This experiment helped prove that the ether does not exist. In 1907 he was awarded the Nobel Prize for Physics for developing extremely precise instruments and conducting important investigations with them, becoming the first American citizen to earn a Nobel Prize.

Michelson was born in Strelno (now Strzelno, Poland), taken to the United States as a child, and educated at the United States Naval Academy and at the universities of Berlin, Heidelberg, and Paris. He was Professor of Physics at Clark University from 1889 to 1892, and from 1892 to 1929 was head of the Department of Physics at the University of Chicago. He determined the velocity of light with a high degree of accuracy, using instruments of his own design.

In 1887 Michelson invented the interferometer, which he used in the famous experiment, performed with the American chemist Edward Williams Morley. At that time, most scientists believed that light travelled as waves through the ether. They also believed that the Earth travelled through the ether. The Michelson-Morley experiment showed that two beams of light sent in different directions from the Earth were reflected at the same speed. According to the ether theory, the beams would have been reflected in waves of different speeds, in relation to the velocity of the Earth. In this way the experiment proved that the ether did not exist. The negative results of the experiment were also useful in the development of the theory of relativity. Michelson's major works include The Velocity of Light (1902) and Studies in Optics (1927).