The Michelson-Morley experiment (here MM-experiment) might be the main experiment, which has influenced Albert Einstein for his Theory of Special Relativity. In public it is often stated that this experiment has proved Special Relativity, although physicists know that this is not the case.
Michelson and Morley wanted to prove by an interferometer the existence of an absolute constant reference frame for light speed. At that time the corresponding medium of the reference frame was called ether, now it is called dark matter.
Result of MM-Experiment:
The difference in light speed to different directions is less than 8 km/s, which is in the range of the accuracy of the MM-experiment.
Questions to answer:
1) Which of the statements below are scientific conclusions from MM-experiment?
2) Which of the statements below are not possible (independently from MM-experiment)?
Choice of test answers:
A) As the absolute velocity of the equipment of MM-experiment (i.e. earth surface) is not known, the speed of light is independent from speed of source and speed of detector.
B) Speed of light might vary up to 8 km/s, but not more.
C) All reference frames, which have velocities of more than 8km/s relative to earth, can be excluded to be reference frames for light speed; these are for example an absolute constant universal reference, the center of the milky way and the sun.
D) As there are other experiments (Sagnac effect experiments), which show that the earth surface and all matter can also be excluded as reference frame for light speed, the relative speed of light is constant to all frames of reference.