Nothing can travel faster than the speed of light. As such, perceptions of objects and time change as they approach light speed, but the laws of physics remain consistent regardless of speed. Objects will appear shortened and time will appear to slow down around an observer approaching near light speeds, but all quantities still exist as they did before and all causality is preserved, even if observers in different points or traveling at different speeds will report different things.
Inertial frames of reference are at rest or move at constant speed unlike non-inertial frames of reference which are accelerating frames of reference.
According to first postulate of the special theory of relativity, all the laws of physics hold true in all the inertial frames of reference. According to the second postulate, the speed of light (<em>c</em>) is constant everywhere and is independent of the relative motion of the source of light.
