Crystal Ball

This ball is cannot tell you your future and it doesn’t drop to signal the beginning of a new year.  No, this ball illustrates the physics concept of refraction.  When you peer through the curved glass it appears as though the image on the other side is upside down.  This occurs because of how the curved glass refracts, or bends, the light as it passes through the ball.

For more information:

http://www.physicscentral.com/experiment/physicsathome/reversing-arrows.cfm