§2 the postulates 1. the relativity postulate: the laws of physics are the same for observers in all inertial reference frames, no frames is preFerred 2. the speed postulate: the speed of light in vacuum has the same value c in all direction and in all inertial reference frames discussion Einstein relativity develop Newton theory physIcs Mechanics rule rue1.the relativity postulate:the laws of physics are the same for observers in all inertial reference frames.no frames is preferred 2.the speed postulate:the speed of light in vacuum has the same value c in all direction and in all inertial reference frames Einstein relativity develop Newton’s theory discussion physics rule Mechanics rule §2 the postulates