[wyhqwyhd] Spherical pool

Consider playing pool on the surface of a sphere.  Balls travel along great circles, geodesics.

Place some barriers on the sphere for the balls to bounce off of, and some pockets in which to sink.

Ambitiously, build it for real: only one ball is possible, which balances exactly on top of the spherical "table".  When the ball rolls, the table rolls the opposite direction underneath keeping the ball balanced precisely on top.  This continues until friction brings the ball to a stop.  There needs to be some precise tracking.  We need some way of imparting initial rotation to the billiard ball: I think hitting it with a traditional cue will simply knock the ball off.