MichelsonMorleykísérlet

The Michelson–Morley experiment, conducted in 1887 by Albert A. Michelson and Edward W. Morley, was a foundational test of the then-accepted idea of a luminiferous aether and of the isotropy of the speed of light. The central question was whether Earth’s motion through the hypothetical aether would produce a detectable difference in the speed of light along different directions.

The experiment used a Michelson interferometer, an optical instrument that splits a beam of light into two perpendicular paths, reflects the beams back, and recombines them to produce an interference pattern. If the Earth moved through the aether, light traveling with or against the ether wind along each path would take slightly different times to traverse the two arms, causing a measurable fringe shift when the apparatus was rotated.

Michelson and Morley rotated the device and searched for any systematic fringe shifts that would indicate anisotropy in the speed of light. The result, within the precision of the apparatus, was a null one: no significant fringe shifts were observed. The speed of light appeared isotropic and independent of the apparatus’s orientation or the Earth’s motion through space, within the experiment’s limits of accuracy.

The null result challenged the prevailing aether concept and prompted further theoretical and experimental work. It contributed to the development of Lorentz–FitzGerald contraction ideas and, more broadly, laid important groundwork for Einstein’s theory of special relativity, which postulates the constancy of the speed of light in all inertial frames. The experiment remains a landmark in the history of physics for shaping the understanding of space, time, and light.