"It's a big deal. How big a deal you have to measure piece by piece but clearly it is the first major change in our health care system since nineteen sixty-five so that's a long time coming."

VOA: special.2010.03.27

It means that the properties of the system, the properties that describe the system, don't change in time or in space.

它的意思是指，用以描述系统的性质，不随时间或空间改变。

麻省理工公开课 - 热力学与动力学课程节选

It means that the properties of the system, the properties that describe the system, don't change in time or in space.

它的意思是指，用以描述系统的性质，不随时间或空间改变。

麻省理工公开课 - 热力学与动力学课程节选