Thanx for the link to Tom Roberts' & Siegmar Schleif's website re What Is The Experimental Basis of Special Relativity.
I refer to their wording in their Section 3 re Einstein's second postulate......... Any speed of light moves in the "stationary" system of coordinates with determined velocity c, whether the ray be emitted by a stationary or by a moving body.
I like this wording (compared to other wordings that i have seen). It is of course itself made up of two postulates, hencely we should talk of three postulates not two, the third being that the velocity of the emitter does not affect the determined velocity c.
But i want to mention the second postulate -- which now becomes simply.......
Any speed of light moves in the "stationary" system of coordinates with determined velocity c.
Here it is clear to me that Einstein doesn't say that light moves with velocity c -- he says that light moves with determined velocity c.
That makes sense to me.
SR & GR are models, & in these models u have rules for determining the velocity of c (& other things). Then u continue to follow the rules & u determine other numbers. And u relate these numbers to numbers determined by others using the same model. And everyone lives happily ever after.
Re the real velocity of c -- who cares?? It is unlikely to worry anyone unless they have a very accurate clock.
Edited by madmac, 22 February 2017 - 08:24 AM.