Michelson–Morley experiment — attempt to detect the relative motion of matter through the stationary luminiferous aether
The 1887 experiment found no evidence of an aether wind, providing the first strong empirical challenge to aether theory and helping lay groundwork for special relativity.
Key Facts
- Experiment period
- April to July 1887
- Published
- November 1887
- Performed by
- Albert A. Michelson and Edward W. Morley
- Institution
- Case Western Reserve University, Cleveland, Ohio
- Result
- No significant difference in speed of light across directions
- Modern confirmation (2009)
- Absence of aether wind confirmed at 10⁻¹⁷ level
By the Numbers
Location
Cause → Event → Consequence
Nineteenth-century physics held that light waves required a medium called the luminiferous aether to propagate through space, just as sound requires air. Scientists expected Earth's motion through this stationary aether to produce a detectable 'aether wind' that would cause measurable differences in the speed of light in different directions.
Between April and July 1887, Michelson and Morley used a highly sensitive interferometer at what is now Case Western Reserve University to compare the speed of light in perpendicular directions. Their measurements found no significant difference in light speed regardless of orientation, producing a null result that contradicted aether theory predictions.
The null result became the first strong evidence against prevailing aether theories and prompted further experiments over subsequent decades. It initiated a line of inquiry that contributed directly to Einstein's development of special relativity, which dispenses entirely with the concept of a stationary aether. Repeated modern experiments have continued to confirm the original finding with ever-greater precision.