The Michelson and Morley experiment always seems to be the experiment that caused the dismissal of the aether and that lead to special relativity. I cannot see why this is, granted it contributed to these two points but in no more away then say the Fizeau experiments or experiments into stellar aberration. In fact, I think it was the contradiction between the results of these three experiments that lead to the dismal of the aether (as they thought of it at the time). So here is my question: Why is the Michelson and Morley experiment seen as the most important of these (and other experiments like them)? And how did this lead to the special theory of relativity?

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    $\begingroup$ See this answer hsm.stackexchange.com/questions/622/… $\endgroup$
    – Conifold
    Mar 23, 2015 at 19:30
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    $\begingroup$ You seem to be assuming that the MM experiment was important as a clue leading to SR. This is basically not true, or at best debatable; it may be depicted that way in textbook presentations of the subject, but textbook presentations generally do not give accurate accounts of the history. For a more careful historical account, see van Dongen, arxiv.org/abs/0908.1545 . Einstein's motivation for SR was a theorist's motivation: he looked at the structure of Maxwell's equations and said that they didn't fit the structure of Galilean relativity. $\endgroup$
    – user466
    Mar 27, 2015 at 4:07

2 Answers 2


The crucial thing to dismissal of the aether was not this experiment but the special relativity. There were alternative theories explaining the outcome of this experiment. The main base of the special relativity was not this experiment but Maxwell's theory of electromagnetism, from which it is a logical consequence. (And Maxwell's theory of magnetism was very well established, not only by experiments but by many practical applications.) But the experiment nicely confirms it, of course.

Michelson-Morley experiment, unlike the earlier experiments measures the speed of light with very high accuracy, due to the novel technology based on interference.


Experimentul M-M a demonstrat ca densitatea masica a luminii s-a insumat cu densitatea masei emanata din substanta pamantului. La descifrarea constantei de actiune h s-a gasit ca fotonul, cuanta de lumina are volum, densitate, masa, presiune, inertie, impuls si energie cinetica. Si deci este graunte de substanta. In continuare s-a gasit ca densitatea masei este data de patratul inductiei magnetice de la nivelul fiecarei semilungimi de unda a nucleonului sau a fotonului. Campul densitatii masice, emanat din substanta pamantului, nu se anuleaza, nu dispare la suprafata pamantului, ci emana in spatiu cu atenuare exponentiala. Existenta campului de densitate, emanat din substanta pamantului, face sa functioneze principiul relativitatii, care nu permite determinarea starii de miscare, a unui sistem, prin experimente din interiorul sistemului.

The M-M experiment showed that the mass density of light was added to the density of the mass emanating from the earth's substance. When deciphering the action constant h it was found that the photon, the amount of light has volume, density, mass, pressure, inertia, momentum and kinetic energy. And so it is a grain of substance. It was further found that the density of the mass is given by the square of the magnetic induction at each wavelength of the nucleon or photon. The field of mass density, emanating from the substance of the earth, does not cancel out, does not disappear at the surface of the earth, but emanates in space with exponential attenuation. The existence of the density field, emanating from the substance of the earth, makes the principle of relativity work, which does not allow the determination of the state of motion of a system, through experiments inside the system.


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