PeterDonis
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Speady said:Inferring something based on an assumption is different from a measurement or hard evidence.
True, but irrelevant, since we have plenty of measurements and hard evidence regarding the speed of light. It seems as though you do not understand what this evidence means, physically.
Speady said:Since a speed is a length divided by a time duration at all times, I cannot avoid different speeds if I divide the same length by different durations.
Which is not what is going on with the relativistic Doppler shift. @Ibix has already explained what is going on and why it is perfectly consistent with an invariant speed of light.