Special relativity to a first observer O, and frame S′ (pronounced "S prime") belongs to a second observer O′. Since there is no absolute reference frame in relativity theory, a concept of 'moving' doesn't strictly exist, as everything is always moving with respect to some other reference frame. Instead, any two frames that move at the same speed in the same direction are said to be "comoving". Therefore, "S" and "S"′ are not "comoving". The principle of relativity, which states that physical laws have the same form in each inertial reference frame, dates back to Galileo, and was incorporated into Newtonian physics.
Postulates of special relativity are not consistent with Galilean relativity unless one postulates the existence of a physical aether. In a surprising number of cases, the laws of physics in special relativity (such as the famous equation formula_28) can be deduced by combining the postulates of special relativity with the hypothesis that the laws of special relativity approach the laws of classical mechanics in the non-relativistic limit. Postulates of special relativity 1. First postulate (principle of relativity) 2. Second postulate (invariance of "c") The two-postulate basis for special relativity is the one historically used by Einstein, and it remains the starting point today. As