It is possible for the electron beam in a television picture tube to move across the screen at a speed faster then the speed of light Why does this not contradict special relativity?

Answer 1

Because nothing physical is actually moving faster than light. All that is moving faster than light is the intersection/impact point of the beam with the phosphor on the CRT face.

The same effect can be observed in a thought experiment using a giant scissors hundreds of lightyears in length. Closing the blades, even though no physical part of the scissors ever moves faster than light, at some distance away from the fulcrum the point at which the two blades intersect will be moving away from the fulcrum at the speed of light with points beyond it intersecting even faster. Of course one could not do this experiment in practice as any physical scissors of these dimensions would be under enormous stress to bend and it would shatter. The electron beam bends with no stress as it is not solid but is a moving stream, like water from a hose..