Two crucial biconditionals (if-and-only-if propositions):

Biconditional 1: The speed of light is constant as per Einstein IF AND ONLY IF the wavelength of light is variable.

Biconditional 2: The speed of light is variable as per Newton IF AND ONLY IF the wavelength of light is constant for a given emitter.

Both biconditionals are immediate logical consequences of the formula

(frequency) = (speed of light) / (wavelength)

Both the antecedent and the consequent in Biconditional 2 are true. The consequent,

"the wavelength of light is constant for a given emitter",

will become the fundamental axiom of future, Einstein-free physics.

The fundamental axiom of Einstein's physics is "the speed of light is constant", the antecedent in Biconditional 1:

"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

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