Movies illustrating special relativity

The nature of light signals A light pulse This movie shows a light pulse expanding spherically outwards.

The Lorentz contraction Dependence on relative velocity of frames This movie shows the world lines of the ends of two identical measuring rods in an inertial frame, one (red) at rest and the other (blue) moving with constant velocity. As the movie goes on, the velocity of the moving rod varies. This illustrates how the Lorentz contraction of the moving rod depends on the rod's velocity.