An Etymological Dictionary of Astronomy and Astrophysics
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An apparatus that produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. It is used to measure very precise lengths, such as the wavelength of light, and for high-resolution spectroscopy.

Named after Albert Abraham Michelson (1852-1931), German-American physicist, who built the interferometer for the → Michelson-Morley experiment of 1887; → interferometer.

Andarzanešsanj, → interferometer.

An experiment performed in 1887 to establish the presence or absence of an → ether, a medium through which light was supposed to travel. The experiment aimed to measure the speed of light coming from different directions. However no → ether drift was found. The null results obtained showed that the ether hypothesis was incorrect. Consequently, the theory of → special relativity, with its hypothesis that the speed of light is the same in all → inertial frames, reconciled the results of the Michelson-Morley experiment with the rest of physics.

→ Michelson interferometer; Michelson received the Nobel Prize in 1907 for his work, the first American to receive the Prize in science. Edward Williams Morley (1838-1923), an American chemist; → experiment.