Dynamical billiards

Summary

A dynamical billiard is the motion of a point particle in a region, called the table. The particle moves in straight lines at constant speed. At the boundary it bounces, with angle of reflection equal to angle of incidence. The shape of the table alone decides the behaviour: some tables give regular, integrable motion, others give chaotic, ergodic motion. Billiards are model systems for the ergodic hypothesis of statistical mechanics and for quantum chaos. The Sinai billiard and the Bunimovich stadium are the classical chaotic examples.