- #1
berra
- 21
- 0
I am wondering how big the local coordinate charts in a coordinate atlas of General Relativity can be. Is it just a few nanometres or all the way to the furthest stars? Also I wonder how the speed of light is defined in GR. Is the velocity defined as the differential with respect to coordinate time? Is the coordinate time only defined with respect to an observer, so a coordinate time is always (a diffeomorphism away from) a proper time?