Marco Bertamini and Andrew Irving : “Once Upon A Time”. UK
How do we know how things are moving? Only by the way that the motion of one object looks compared to other objects. This leads to multiple interpretations of the same motion. In short, all motion is relative (to some frame of reference). This is true in physics and also, for the same reasons, in perception. Each of the motions in the video is the same with respect to one frame (the screen) but each is affected by a different moving frame of reference, thus appearing different.