For example, can we really know or prove that the speed of light is constant?
All the evidence we have from the past 100 years of testing and retesting says yes lightspeed is constant. Without any exception.
Do you have any evidence to put forth that challenges this?
that the redshift is entirely due to recessional speed and not due to gravity or some other source of energy decay?
Again, all the evidence we have from literally tens of thousands of observations and lab tests says yes redshift we seen from galaxies is entirely due to recessional speed (expansion of spacetime) and not due to gravity or some other source of energy decay. Explain Andromeda's blue shift.
Do you have any evidence to put forth that challenges this?
Edited by AZPaul3, : No reason given.
Edited by AZPaul3, : clarity
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