Albert Einstein: "...I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz's theory of the stationary luminiferous ether..."
https://en.wikipedia.org/wiki/Lorentz_ether_theory

Albert Einstein: "In view of this dilemma there appears to be nothing else for it than to abandon either the principle of relativity or the simple law of the propagation of light in vacuo. Those of you who have carefully followed the preceding discussion are almost sure to expect that we should retain the principle of relativity, which appeals so convincingly to the intellect because it is so natural and simple. The law of the propagation of light in vacuo would then have to be replaced by a more complicated law conformable to the principle of relativity. The development of theoretical physics shows, however, that we cannot pursue this course. The epoch-making theoretical investigations of H. A. Lorentz on the electrodynamical and optical phenomena connected with moving bodies show that experience in this domain leads conclusively to a theory of electromagnetic phenomena, of which the law of the constancy of the velocity of light in vacuo is a necessary consequence."
http://www.bartleby.com/173/7.html

So Einstein did not abandon the constancy of the speed of light because ... Lorentz's ether theory had shown that the constancy is correct! The fundamentals of Einstein's relativity are extremely solid, aren't they, Einsteinians?

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