I meter is one meter only in inertial frames. As E put it "Special principle of relativity: If a system of coordinates K is chosen so that, in relation to it, physical laws hold good in their simplest form, the same laws hold good in relation to any other system of coordinates K' moving in uniform translation relatively to K."
Only those objects moving in uniform translation (the same approximate speed) relatively (in relation) to each other, can the same laws of physics be applied. You can not shrink your ruler and still call it a meter and get the correct results for the speed of c. The ruler shrinks in proportion to energy gained. As your speed increases, the distance you measure for light becomes less as your ruler shrinks. Because it IS traveling at a constant speed, slower or faster in relationship to your velocity - which is proportional to energy content.
It only "appears" c in all frames because in every frame the ruler is longer or shorter depending on energy gained from speed of motion. And you still call that longer or shorter ruler a meter, regardless if it is shorter or longer than what you define as a meter in this frame.
You are shrinking or enlarging rulers through transformations, yet insist they are the same length. If they were the same length, no transformation would be required because the same laws of physics would hold good in both frames. In every frame of reference that is not inertial - every single measuring device that exists in that frame changes and measures a new measurement - proportional - to the energy gained or lost. But because you still call what is now different, the same name - you have blinded yourself willingly to the truth and don't even see it.
No wonder relativists think nothing is bending!!!
