Einstein wrestled with his conscience "over a lengthy period of time, to the point of despair" before introducing the constant-speed-of-light nonsense:

John Stachel: "But this seems to be nonsense. How can it happen that the speed of light relative to an observer cannot be increased or decreased if that observer moves towards or away from a light beam? Einstein states that he wrestled with this problem over a lengthy period of time, to the point of despair." http://www.aip.org/history/exhibits/...relativity.htm

The nonsense proved highly malignant - it gradually permeated the whole of physics and killed this branch of science (converted it into an insane ideology):

"He opened by explaining how Einstein's theory of relativity is the foundation of every other theory in modern physics and that the assumption that the speed of light is constant is the foundation of that theory. Thus a constant speed of light is embedded in all of modern physics and to propose a varying speed of light (VSL) is worse than swearing! It is like proposing a language without vowels." http://www.thegreatdebate.org.uk/VSLRevPrnt.html

John Stachel's "seems to be nonsense" is a euphemism. The constancy of the speed of light is OBVIOUS NONSENSE:

https://www.youtube.com/watch?v=bg7O4rtlwEE

The speed of the light pulses as measured by the stationary observer is

c = df

where d is the distance between the pulses and f is the frequency measured by the stationary observer. The speed of the pulses as measured by the moving observer is

c'= df' c

where f' f is the frequency measured by the moving observer.

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