This exhibit is based on the principle used to make the first 3-D movies. Hanging objects are illuminated by two projectors. One projector has a red filter, the other has a green filter. On the screen, each object produces two shadows-one from each projector. Where an object blocks the red light, there is a green shadow; where an object blocks the red light, there is a green shadow. The viewers contain red and green filters: the left eye looks through a red filter, the right eye looks through a green filter. Through the red filter, the red shadow looks dark; through the green filter, the green shadow looks dark. Each eye sees a differently placed shadow of an object. The brain combines these two shadows and sees a single, fused image in 3-D space. Thus, all the objects between the projectors and the screen are reproduced as shadows floating in space between the viewer and the screen.