The apparent arrow of time emerges as a property of the macroscopic system, but it's not there in the laws that govern the individual particle interactions.

很显然时间箭头成为了宏观系统的一种性质，但没有定律来控制单个原子间的相互作用。

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The nonequilibrium statistical operator (NSO) of the system is constructed and a series of macroscopic equations for its particle number, momentum, energy, force aad entropy etc. are derived.

构成了此体系的非平衡统计算符，进而导出其粒子数、动量、能量、力和熵等一系列宏观方程。

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After reflection, the average particle velocity near free surface is equal to twice the piston velocity approximately, which agrees with macroscopic phenomena.

激波在自由面反射后，自由表面附近的粒子速度为活塞速度的二倍，这和宏观力学结果相同。

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