Can someone give me a good plausible answer

[ZapperZ]

Why do physicists consider that the vacuum between the Earth and the sun is different to the vacuum between a nucleus and an electron?
They must think there is a difference because theory treats the two cases differently. What we observe when light passes from air to water is the same as what happens when light passes from the earth, grazes the solar surface and is reflected by a target beyond the sun.
Accepted theory says that light slows down when passing from air to a denser medium such as water, but accepted theory says that light has to travel a "longer spacetime distance" and has nothing to do with light being "slowed down" in the solar case. This is pure double talk whether you like it or not.

Note that, if you had read our FAQ, you would have noticed that even in a dense medium, the speed of photons do not slow down. This is a common misconception one has when the idea of WHAT is being measured is never considered. "god" is in the details, and this is especially true on when we consider the speed of a light pulse, which is what is commonly measured, and what is measured in a dense medium.

There is no double talk here if one has understood beyond just the superficial level of light transport.

Zz.

 

[rewebster]

z:

'"god" is in the details'

now where (or how) did you get that one?--(I've heard it differently before)-

-that's pretty funny, there, Z, (I like it)

 

[rbj]

As long as your distances are short enough, acceleration doesn't really matter, as George points out. I probably overspecified things a bit by stating that the rulers should be in free fall.

no, no! i thought you were being nicely conservative (which was persuasive to me). certainly, at least for the observer in free-fall, the speed of propagation (EM, whatever) would still be the constant c around a gravitational mass, if we accept the postulates of GR. i got it, and then tried to extrapolate that to the guy standing on the cliff and not in free fall. then applying the equivalence principle again, if it's the same c for the guy standing on the cliff, it's the same c for the guy in the rocket accelerating at the same rate, g.

But on the other hand there's a whole can of worms about "distance in the large" that one can sidestep by this sort of specification. This could probably start a whole new thread, this thread is probably confused enough without hijacking it in that direction.

i just thought that the direction it was in, regarding the OP, was a little icky.