Consider this:
"Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887...The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)." https://en.wikipedia.org/wiki/Emission_theory
So in 1887 the null result of the Michelson-Morley experiment was compatible with variable (dependent on the speed of the emitter, c'=c±v) speed of light. The following question is forbidden (let alone the answer):
Was the null result simultaneously (in 1887) compatible with constant (independent of the speed of the emitter, c'=c) speed of light?
Why is the situation so dramatic? The answer 'yes' is obviously idiotic. The answer 'no' is suicidal for physicists. The texts below imply that, if the speed of light is variable, modern physics, predicated on Einstein's 1905 constant-speed-of-light falsehood, is long dead (exists in a zombie state):
Bryan Wallace: "Einstein's special relativity theory with his second postulate that the speed of light in space is constant is the linchpin that holds the whole range of modern physics theories together. Shatter this postulate, and modern physics becomes an elaborate farce!...The speed of light is c+v." http://www.kritik-relativitaetstheorie.de/2013/02/the-farce-of-physics-2/ Note: Bryan Wallace wrote "The Farce of Physics" on his deathbed so one should not judge him too severely for (numerous) imperfections.
Joao Magueijo, Niayesh Afshordi: "The whole of physics is predicated on the constancy of the speed of light...So we had to find ways to change the speed of light without wrecking the whole thing too much." https://motherboard.vice.com/en_us/article/8q87gk/light-speed-slowed
"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
"If there's one thing every schoolboy knows about Einstein and his theory of relativity, it is that the speed of light in vacuum is constant. No matter what the circumstances, light in vacuum travels at the same speed...The speed of light is the very keystone of physics, the seemingly sure foundation upon which every modern cosmological theory is built, the yardstick by which everything in the universe is measured...The constancy of the speed of light has been woven into the very fabric of physics, into the way physics equations are written, even into the notation used. Nowadays, to "vary" the speed of light is not even a swear word: It is simply not present in the vocabulary of physics." https://www.amazon.com/Faster-Than-Speed-Light-Speculation/dp/0738205257
"Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887...The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)." https://en.wikipedia.org/wiki/Emission_theory
So in 1887 the null result of the Michelson-Morley experiment was compatible with variable (dependent on the speed of the emitter, c'=c±v) speed of light. The following question is forbidden (let alone the answer):
Was the null result simultaneously (in 1887) compatible with constant (independent of the speed of the emitter, c'=c) speed of light?
Why is the situation so dramatic? The answer 'yes' is obviously idiotic. The answer 'no' is suicidal for physicists. The texts below imply that, if the speed of light is variable, modern physics, predicated on Einstein's 1905 constant-speed-of-light falsehood, is long dead (exists in a zombie state):
Bryan Wallace: "Einstein's special relativity theory with his second postulate that the speed of light in space is constant is the linchpin that holds the whole range of modern physics theories together. Shatter this postulate, and modern physics becomes an elaborate farce!...The speed of light is c+v." http://www.kritik-relativitaetstheorie.de/2013/02/the-farce-of-physics-2/ Note: Bryan Wallace wrote "The Farce of Physics" on his deathbed so one should not judge him too severely for (numerous) imperfections.
Joao Magueijo, Niayesh Afshordi: "The whole of physics is predicated on the constancy of the speed of light...So we had to find ways to change the speed of light without wrecking the whole thing too much." https://motherboard.vice.com/en_us/article/8q87gk/light-speed-slowed
"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
"If there's one thing every schoolboy knows about Einstein and his theory of relativity, it is that the speed of light in vacuum is constant. No matter what the circumstances, light in vacuum travels at the same speed...The speed of light is the very keystone of physics, the seemingly sure foundation upon which every modern cosmological theory is built, the yardstick by which everything in the universe is measured...The constancy of the speed of light has been woven into the very fabric of physics, into the way physics equations are written, even into the notation used. Nowadays, to "vary" the speed of light is not even a swear word: It is simply not present in the vocabulary of physics." https://www.amazon.com/Faster-Than-Speed-Light-Speculation/dp/0738205257