Differences Between the Galilean Principle of Relativity and Einstein's Special Principle of Relativity As just described, the Galilean principle of relativity indicates that Newtonian mechanics apply across inertial frames when linked with the Galilean transformation. On the other hand, the assumption that the speed of light is constant in any reference frame forced scientists to reformulate the Galilean transformation to be consistent with rela- tivity. This new transformation is called the Lorentz transformation. The Lorentz transformation is shown by the equations below, which show the relation- ship between coordinates from a coordinate system at rest and a coordinate system moving at a constant velocity v relative to the coordinate system at rest. The variables with the prime symbol () attached represent coordinates observed from the coordinate system at rest; the variables without the prime symbol represent coordinates observed from the system in motion. Note that the speed of light c appears in the equations here. Another point to notice is that time t is transformed in a manner similar to that of length; time does not exist independently but must be considered to be unified with space. x = x - vt v 1 - c t - 2 v x c 2 t = 2