Michelson-Morley Experiment
Physics: AQA A Level, topic 12.3.1
Michelson-Morley Experiment
The Michelson-Morley experiment disproved absolute motion.
Absolute motion
- In the past, there was no concept of relative motion.
- Scientists believed that everything must move relative to a fixed object or origin.
- This fixed object was called the ether.
Michelson-Morley experiment
- Michelson and Morley tried to find the absolute speed of the Earth using an interferometer.
- They used two mirrors and a partial reflector to send a beam of light in two perpendicular directions.
- These beams are reflected back, and recombined to form an interference pattern.
- Based on the shift in the interference patterns when the experiment is run in different orientations, the speed of the Earth should have been calculated.
Results
- Michelson and Morley repeated the experiment, but could never find any results from their interference patterns.
- They concluded that:
- Absolute motion is impossible to detect.
- The speed of light is equal for all observers.
Test yourself on Michelson-Morley Experiment
What was the name of the fixed reference that people believed that everything moved relative to?
Michelson-Morley Experiment