You know, if you want to measure the potential energy of something in a gravitational field, you have to define the zero somewhere, right, because it's arbitrary. You can set it anywhere you want. It's the same with enthalpy.

你知道，如果你想测量重力场,中某种东西的势能，你需要，在某处定义一个零点，对吧？,因为势能的值是任意的,你可以把它设定在。

麻省理工公开课 - 热力学与动力学课程节选

So what we do is we pick an origin, call it zero, we put some markers there to measure distance, and we say this guy is sitting at 1,2,3,4,5.

我们现在选择一个原点,称其为零点,我们做一些标记来测量距离,这个点在五个单位长度的地方

耶鲁公开课 - 基础物理课程节选