33 Incredible Shadows Which Will Make You Look Twice

Although the edge of a shadow appears to "move" along a wall, in actuality the increase of a shadow's length is part of a new projection which propagates at the speed of light from the object of interference. Since there is no actual communication between points in a shadow (except for reflection or interference of light, at the speed of light), a shadow that projects over a surface of large distances (light years) cannot convey information between those distances with the shadow's edge.