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

This simulation has a duration of 512 time steps. Between t=256 and t=257, all velocities are reversed. Unfortunately, the system state a t=512 is very different from the previous 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).

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