Relativity, Physics, Math, Einstein, Spacetime.
arisen. — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Furthermore, the principle of relativity teaches us that, as judged from K, the length of a unit measuring-rod which is at rest with reference to K’ must be exactly the same as the length, as judged from K’, of a