Richard Feynman: "I want to emphasize that light comes in this form - particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you probably learned something about light behaving like waves. I'm telling you the way it does behave - like particles. You might say that it's just the photomultiplier that detects light as particles, but no, every instrument that has been designed to be sensitive enough to detect weak light has always ended up discovering the same thing: light is made of particles." QED: The Strange Theory of Light and Matter p. 15 https://www.amazon.com/QED-Strange-T.../dp/0691024170

Needless to say, elsewhere Feynman says different things but still let us take the above words at face value and draw two implications. The first implication is obvious - the speed of light is variable as per Newton, as originally (prior to FitzGerald and Lorentz introducing, ad hoc, contracting lengths) proved by the Michelson-Morley experiment:

"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

"The Michelson-Morley experiment is fully compatible with an emission theory of light that CONTRADICTS THE LIGHT POSTULATE." http://philsci-archive.pitt.edu/1743/2/Norton.pdf

The second implication of Feynman's text sounds strained but I have already shown that it can be justified independently of the light-is-made-of-particles assumption. Nothing in a flying particle would become longer or shorter if the emitter (or receiver) starts moving, or if the particle falls in a gravitational field. So the wavelength of light, no matter how it relates to the particle model of light, remains constant (for a given emitter).

Hence the fundamental axiom of future, Einstein-free physics:

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

Combined with the formula

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

the axiom provides the fundamental law of Einstein-free physics:

"Any frequency shift entails (is caused by) a proportional speed-of-light shift"

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