We all know about that. Surely? No I don't. All I need to do is refer to The Other Meaning of Special Relativity by Robert Close. He refers to the wave nature of matter, and explains that when waves are all there is, you calibrate your rods and clocks using the motion of waves, then use them to measure the motion of waves. Hence you have the tautology described by Magueijo and Moffat in http://arxiv.org/abs/0705.4507 : "Following Ellis , let us first consider c as the speed of the photon. Can c vary? Could such a variation be measured? As correctly pointed out by Ellis, within the current protocol for measuring time and space the answer is no. The unit of time is defined by an oscillating system or the frequency of an atomic transition, and the unit of space is defined in terms of the distance travelled by light in the unit of time. We therefore have a situation akin to saying that the speed of light is “one light-year per year”, i.e. its constancy has become a tautology or a definition." I'm not abandoning experiment. I've referred to the Shapiro delay and NIST optical clocks and the GPS clock adjustment. Er no, I'm the guy who points out the evidence. You're the one who ignores it. And the OP and Ned Wright and Don Koks and Einstein. Only I do comprehend basic math. You're clutching at straws.