[burzum]

One typical such “thought experiment” was called the “mirror clock experiment”. Thought experiments are not a rational basis for physics. There are any number of huge problems with relativity not least of which is the instantaneous propagation of gravity, and there are other more plausible explanations for the non additivity of light.

Well here is a piece of experimental evidence for you: I have personally measured muons with a scintillation detector. They travel at a extremely high speed and would decay before reaching the surface of the earth if it wasn't for relativistic time dilation.

[jeddavis]

Gravity propagates instantaneously to within our ability to measure it and that has been known for several centuries. Every time you take five steps you are sending a gravitational message out into the cosmos and somebody on the far side of our galaxy with a sensitive enough instrument could read that message and it wouldn’t take him thousands of years to do it; he’d probably be able to read it inside of a second.

[Paul Ross]

Bump. Good point.