where r 0 and t 0 represent shifts in the origin of space and time, and v is the relative velocity of the two inertial reference frames. Under Galilean transformations, the time t 2 − t 1 between two events is the same for all reference frames and the distance between two simultaneous events (or, equivalently, the length of any object, | r 2 − r 1 |) is also the same.