June 16, 2005 8:07 AM Subscribe
PhysicsFilter: Suppose I'm looking straight ahead at somebody's head, but can't see their eyes because they are obstructed by a wall or railing. Under what physical circumstances can that person see my eyes? Assume that there are no mirrors, cameras, or other visual trickery. Also assume that both people are sitting on chairs at floor level, though they may be of different heights.