Home / Topics / Relativity
Michelson–Morley experiment
Beginner
Found no evidence of an ether wind.
In 1887 Michelson and Morley split light into two perpendicular beams to detect Earth's motion through the supposed ether. They saw no fringe shift, to high precision. The null result undermined ether theories and prepared the ground for relativity.
Expected shift ≈ 0.4 fringe; observed < 0.01.
The result concerns the speed of light being the same in all directions.
In more detail
The Michelson-Morley experiment searched for a stationary aether by comparing light speeds in perpendicular directions. It found no difference, which challenged the idea of a medium for light.
Real-world uses
- It helped motivate special relativity.
- It is a classic example of a precise null experiment.
- The Michelson–Morley result was one of the clues that led Einstein to abandon the idea of a fixed ether and build special relativity.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
What was the aether?
A hypothetical medium thought to carry light, which the experiment failed to detect.
When was it performed?
In 1887 by Albert Michelson and Edward Morley.
What was the ether?
A hypothetical medium thought to carry light waves, which the experiment failed to detect.
Related topics in Relativity
Postulates of special relativity · Relativity of simultaneity · Time dilation