The special theory of relativity explores the consequences of the invariance of c with the assumption that the laws of physics are the same in all inertial frames of reference.
Einstein's first postulate says that the laws of physics are the same and can be stated in their simplest form in all inertial frames of reference. It means that there is no preferred frame and, therefore, no absolute motion.
The speed of light in vacuum c (299792458 m/s) is so enormous that we do not notice a delay between the transmission and reception of electromagnetic waves under normal circumstances. the second postulate is a consequence of the first, since if the speed of light depended on the motion of its source the laws of electrodynamics (which determine the speed of freely propagating electromagnetic waves) would depend on the inertial frame of the source, which contradicts the first postulate.
Go to index page