The discussion centers around the constancy of the speed of light (c) in the context of changing distance and time, exploring the implications of Lorentz transformations and the relativity of simultaneity. Participants question how to prove the equality of c and c' without relying on c in their reasoning.
Participants express differing views on how to approach the proof of the constancy of c, indicating that the discussion remains unresolved with multiple competing perspectives.
Some assumptions regarding the definitions of distance, time, and simultaneity may be implicit in the discussion, and the mathematical steps involved in the arguments are not fully resolved.
If you're talking about the speed of light in a single direction (as opposed to measuring the two-way speed by sending a light beam away from a clock, having it bounce off a mirror and return to the clock, and using that time interval to divide the distance from the clock to the mirror and back), you can't derive it from length contraction and time dilation alone, you also have to take into account the relativity of simultaneity. I gave a numerical example of how it all works out in post #7 of this thread.ChristianKing said:If distance and time can change then how can c be constant? I guess what I'm asking is how can someone prove that c=c' without relying on c in a solution such as setting the Lorentz space contraction over the Lorentz time dilation?