Introduction to Special Relativity

Abstract

Maxwell equations in vacuum space describe the propagation of electromagnetic signals with speed $c \equiv 1/\sqrt {\mu _0 \in _{0 \cdot } }$ . Since, according to Galilean relativity principle, velocities must be added like vectors when going from one inertial reference frame to another, the vector corresponding to the velocity of a luminous signal in one inertial reference frame O can be added to the velocity of O with respect to a new inertial frame O′ to obtain the velocity of the luminous signal as measured in O′. For a generic value of the relative velocity, the speed of the signal in O′ will be different, implying that, if Maxwell equations are valid in O, they are not valid in a generic inertial reference frame O′.