The Michelson–Morley experiment was performed in 1887 by Albert A. Michelson and Edward W. Morley at what is nowCase Western Reserve University in Cleveland, Ohio. It attempted to detect the relative motion of matter through the stationary luminiferous aether (“aether wind”). The negative results are generally considered to be the first strong evidence against the then prevalent aether theory, and initiated a line of research that eventually led to special relativity, in which the stationary aether concept has no role. The experiment has been referred to as “the moving-off point for the theoretical aspects of the Second Scientific Revolution”.
Michelson–Morley type experiments have been repeated many times with steadily increasing sensitivity. These include experiments from 1902 to 1905, and a series of experiments in the 1920s. In addition, recent resonator experiments have confirmed the absence of any aether wind at the 10−17 level. Together with the Ives–Stilwell and Kennedy–Thorndike experiments, the Michelson–Morley experiment forms one of the fundamental tests of special relativity theory.