# Things that do not depend on the choice of Cauchy surface

1. Nov 6, 2015

### naima

A Cauchy surface is a 3d spacelike slice of spacetime.
Could you read the definition (17) p18
the author says that "one can proove that $\sigma$ does not depend on the choice of the Cauchy surface because the functions obey the law of motion."
Could you elaborate?
Thanks

Could any one add "h" in the title (choice)?

2. Nov 7, 2015

### naima

Sorry
I found the proof several lines below!