Question

Explain how the Michelson-Morley experiment works, what the data looks like and what it means, and how the results impacted Modern Physics.

Answer 1

Michelson and Morely experiment was deviced to see if the ether is persistent everywhere in the universe. Initially it was thought that light can not travel with out a medium and the hypothesis was put forward that ether is the omni present medium, which is not visible but pervades the entire space. To prove this theory Michelson Morely experiment was performed.

The idea is to have a beam of light fall on a partially reflecting mirror which is at 45 degrees angle with respect to the incident beam, since the mirror is partially reflecting, a fraction will be reflected at 90 degrees on to a mirror and a fraction would be transmitted to another mirror. Since these two beams which are split will travel unequal distance in space, the resulting beam when mixed into a telescope would show some fringe shift due to the path difference. This experiment was conducted in many places, and many directions just to see if the light speed will be affected by the relative motion between the source and the observer.

Every instance, they would record the fringe shift and try to correlate it with the speed with which the apparatus was moved and etc. They always it would prove that the light is not affected by the movement or relative motion and the speed of light is a constant. So this experiment kind of disapproved the existence of ether pervasion.

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