Michelson, Albert Abraham
Michelson, Albert Abraham (1852-1931), a United States physicist. Michelson was the first United States scientist to receive a Nobel Prize. He was awarded the 1907 prize in physics for measurements of the speed of light and for inventing optical instruments.
An experiment made by Michelson with Edward W. Morley in 1887 profoundly affected physics. They tried to determine the velocity of the earth in relation to a hypothetical substance called the ether. The ether was believed to be a medium through which light travels and to occupy all space not occupied by matter. The experiment showed that the velocity of light was the same in all directions, regardless of the motion of the earth, leading physicists to abandon the ether theory. The fact that the speed of light is the same regardless of the motion of the observer is a basic principle in Albert Einstein's special theory of relativity.
The Michelson-Morley experiment was made possible by Michelson's invention of the interferometer, an extremely sensitive instrument used for measuring differences of length. He used the interferometer to determine the length of the standard meter in terms of a particular wavelength in the spectrum of cadmium. The instrument was also used by Michelson to confirm theories of the rigidity and viscosity of the earth and in 1920, to make the first accurate measurement of the diameter of a star.
Michelson was born in Strelno, Prussia. He was brought to California at the age of two. Michelson graduated from the U.S. Naval Academy in 1873 and was a physics and chemistry instructor there, 1875-79.
While at the academy he developed a revolving mirror apparatus that improved upon earlier methods for determining the speed of light.
After resigning from the navy, Michelson served as professor of physics at the Case School of Applied Sciences (now Case Western Reserve University), 1883-89. He was a professor at Clark University, 1889-92, and at the University of Chicago, 1892-1931, heading the physics department until 1929. Michelson was president of the National Academy of Sciences, 1923-27. He was named to the Hall of Fame for Great Americans in 1970.