This is something that you're going to prove in statistical mechanics, and so we're not going to worry about where this comes from.

我们会在统计力学中,证明这一结论，现在不需要去,操心这一结论的由来。

麻省理工公开课 - 热力学与动力学课程节选

You'd learn about statistical mechanics, and how the atomistic concepts rationalize thermodynamics.

你会学到在统计力学中，是如何用原子论的概念,阐释热力学的。

麻省理工公开课 - 热力学与动力学课程节选

Now, the reason this condition always holds in ordinary mechanics is because you're never, in that case, concerned with a huge statistical population of particles where the disorder among them is an issue.

这个条件在力学中总是成立,这是因为在力学中,我们从来没有关注过大量粒子的统计行为，而对这些系统来说,无序是很重要的。

麻省理工公开课 - 热力学与动力学课程节选