The Lorentz transformations are a group of mathematical functions that are central to the special theory of relativity. They express the constancy of the speed of light in all frames of reference and the dependence of space and time measurements on the relative motion of the observer and the system observed.

The transformations describe how the coordinates of an event in one frame of reference compare with the coordinates as measured in another reference frame that is in motion at constant velocity relative to the first frame. Such transformations can be used to test the invariance of physical laws, showing whether the laws apply universally, regardless of the state of motion of the observer. In the Galilean transformations, which predate the Lorentz transformations, it is implicitly assumed that measurements of lengths and time intervals are not affected by the relative motion of the observers, and that...