The Michelson–Morley experiment was first performed in 1887 by Albert A. Michelson and Edward W. Morley. Its purpose was to compare the speed of light in perpendicular directions, in an attempt to detect the relative motion of matter through the stationary luminiferous aether and use the rotation of the earth to shift the light for study.

The surprising result of this experiment is that the earth did not measurably rotate at all, in contradiction to all expectations. Michelson and Morley repeated the experiment many times, and in many different positions and configurations, all with a null result. The earth was seen to be motionless. The experiment has been referred to as "the moving-off point for the theoretical aspects of the Second Scientific Revolution" and directly influenced the creation of Albert Einstein's theory of General Relativity. General Relativity subsequently found favor among many scientific circles because the model of space of GR was designed to seemingly explain the motionless earth result of the Michelson-Morley experiment, allowing the theory of the earth's rotation to survive contradicting experimental evidence.

http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/mmhist.html

"Although repeated over the next 40 years with ever greater precision and the same negative result, this 1887 experiment is pointed to as one of the experimental foundations of relativity, and earned Michelson the Nobel Prize in 1907."

York University Slideshow

Material from a York University course provides a good summary of the Michelson-Morley experiment and its results. Below are selected slides.

Class Description
Full Slideshow

Peer Review and Repetitions

Since 1887 the Michelson-Morley experiment has been repeated and verified on a number of occasions.

2009 Repetition in Germany

https://physicsworld.com/a/michelson-morley-experiment-is-best-yet/

Michelson–Morley experiment is best yet

"Physicists in Germany have performed the most precise Michelson-Morley experiment to date, confirming that the speed of light is the same in all directions. The experiment, which involves rotating two optical cavities, is about 10 times more precise than previous experiments – and a hundred million times more precise than Michelson and Morley’s 1887 measurement."