Consider the system of n identical hard balls in ${\mathbb {R}}^3$ moving freely and colliding elastically. We show that there exist initial conditions such that the number of collisions is exponential in n.

中文翻译：

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硬球系统中指数级多次碰撞的示例

考虑系统n相同的硬球${\mathbb {R}}^3$自由移动和弹性碰撞。我们证明存在初始条件使得碰撞次数在n.