light is either a wave that behaves like a particle or a particle that behaves like a wave. either way, it has wave characteristics.
No matter how we approach this issue we are confronted with the standard conclusions. Namely, Light fro any source in a vacumn will always travel at the same speed.
There is an assumption that is open to challenge in that it is being assumed that vacuum is stationary, while something other than vacuum moves.
Look at the other possibility. Consider that vacuum exists in the form of particle fields that move through 'something' (the vacuum force carrier).
Speed is determined by force carrier density. The vacuun field does not loose momentum it slows down and speeds up according to the density of the force carrier. A photon approaching a black hole slows down. If it escapes it speeds up because vacuum field momentum is conserved. But in current interpretation, because the particle is something momentum is lost during deceleration and cannot be replaced without cause. Whereas a particle size vacuum field obeys the rule v=f/d (v=speed; f=field force; d= background density).
In reality particles (gravitons) form the background and their density is determined by the presence of other particles (mass distorts gravity).
