I'm not a physicist, I'm just repeating something I read
somewhere (I cant even remember where).
As far as I know, general relativity relies on the existence of a finite speed upper bound. It appears that this bound is equal to the speed of light, but any higher speed would do.
I understand that, although my own explanation is more along the lines that c represents a fundamental constant describing the geometry of space, and that the reason no physical object can travel faster than light is that the speed of light represents the shortest distance in space-time between any two points.
As far as I know, general relativity relies on the existence of a finite speed upper bound. It appears that this bound is equal to the speed of light, but any higher speed would do.