100 million ball mushroom billiard is (not) chaotic

The Bunimovich mushroom billiard is chaotic for some initial conditions and integrable/non-chaotic for some other, which is perhaps not too surprising considering the geometry of the domain. 1. Starting in the foot is always chaotic, regardless of the initial velocities. 2. Starting high in the hat is typically non-chaotic depending on the initial velocities. Here is shown a non-chaotic time evolution. 3. Here the initial conditions are such that half of the point distribution exhibits chaos (orange/yellow) whereas the cyan part is non-chaotic. Music by ‪@gpcbass‬ . The song is called Alhambra and used on this channel before. Visuals in Python and FFmpeg. Matplotlib was used in 1. and 2., whereas PIL was used in 3.