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The numerical irreversibility of the bidimensional billiard [L'irréversibilité numérique du billard bidimensionnel].

This simulation has a duration of 512 time steps. At t=0 just one particle starts moving (at the center). Between t=255 and t=256, all velocities are reversed. Unfortunately, the system state at time t=512 is very different from the initial state (at time t=1). In actuality, this system is very sensitive to initial conditions and therefore, it is sensitive to rounding-off errors; this phenomenon can be seen on this picture The same bidimensional rectangular billiard with 41x56 random particles studied on two different computers -the Green one and the Red one- where the same computation is done on two different computers: the Green one (a PC under Linux) and the Red one (a SGI O200 under IRIX 6.5).

See a related picture:

The numerical irreversibility of the bidimensional billiard -1376 particles-

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