# stationary

Roughly speaking, in relativity, a situation or a spacetime is stationary if there is no change over time.

To be more precise, one has to take into account that, in general relativity, time can be defined in many different ways, all of them equally valid for formulating the laws of physics. This leads to a modified definition: A situation or a spacetime is stationary if it is possible to define time in a way so that there is no change over time - if you follow the properties of a given region of space over time, they will not change.