Jeppe Hein’s big mirror ball is a polished steel ball that’s 30 inches in diameter and moves about the room whenever anyone enters the room. it moves fairly slow and in random directions. it bumps into people, walls, or whatever gets in its way. when it hits something it takes a short pause and then begins to go again. this provokes the publics reaction because they can make it move but they don’t have complete control over the ball.