MichelsonMorleyexperimentet

The Michelson–Morley experiment, conducted in 1887 by Albert A. Michelson and Edward W. Morley, sought to detect the luminiferous aether by measuring the relative motion of Earth through this presumed medium. The central idea was that light traveling in the direction of Earth’s motion through the aether would have a different travel time than light traveling perpendicular to that motion, producing a measurable shift in an interference pattern.

The researchers built a Michelson interferometer, which splits a single light beam into two perpendicular paths using a half-silvered mirror. Each path reflects off a mirror and then recombines at the beam splitter to produce an interference pattern. By rotating the apparatus, the orientation of the paths with respect to the supposed aether wind would change, and any resulting fringe shifts would indicate a difference in light speed along the two directions.

The result of the experiment was a null outcome: no significant fringe shifts were observed as the apparatus was rotated. The measured interference pattern remained effectively constant, providing strong evidence against the existence of the aether wind in the forms proposed at the time. This null result challenged the prevailing ether theory and was later reconciled within the framework of Einstein’s special relativity, which postulates the constancy of the speed of light in all inertial frames.

The Michelson–Morley experiment is regarded as a foundational milestone in physics. It motivated further high-precision tests of Lorentz invariance and contributed to the shift away from the luminiferous aether toward modern theories of space, time, and light.