This follows up the Single Time Zone on a spherical planet.

Suppose now we have many habitual planets in a Solar system or in a Galaxy.

How does it work to set up a Universal Time? Will it be feasible to set up a Single Time Zone in a Solar system or in a Galaxy?

Obviously, if the spatial scales are beyond the Solar system,

  • the special relativity +spacetime+kinematics) and

  • general relativity (+gravity)

  • synchronization of clocks when we have high speed travelers,

may be involved.