If I place my container of gas on the table here, and I come back an hour later, the pressure needs to be the same when I come back Otherwise it's not equilibrium.

如果我把装气体的容器放在桌子上，一小时以后我再回来时,气体的压强应该是不变的,否则它就不是平衡的。

麻省理工公开课 - 热力学与动力学课程节选