Can spacetime slows down and ultimately stops constant light?
The answer is yes. Spacetime has skein, fabric which completely occupies all of outer space. Though light is constant at 186,000 miles per/sec. at vacuum outer space, it does not mean light is all the way at such constant speed from beginning without end.. Pure light is interference or wave on frictionless skein of spacetime. The normal state of such skein is non-interference, thus ultimately light waves will ultimately settle down and rest..no more ripple on spacetime.
Light at underwater or glass is interferred by such body of water or glass, respectively, thus, light is slowed. Light at electrical wires depends on strength on source of light. Also, light is affected by strong gravitational field, such as in black hole.
The effect on light, due to its interference on spacetime,, has not been considered in the computation of speed of light., has further implication to the making of red-shifting.
Jsaldea12
4.18.10