- Sometimes I see people say that region IV describes a whitehole, as if it's separate physical object, some even say that there are two objects in this spacetime - a whitehole and a blackhole. Is this a possible interpretation?
To me it seems incorrect because for any (time-like) observer, there is no way to have both regions II and IV inside the same half of his light-cone or in space-like section orthogonal to the light-cone.
- Although it seems clear that there is no unique way to link time-orientation between regions I and III (because no observer can travel from I to III), I still wonder what would happen in the following scenario:
- imagine there already exists a singularity of mass M.
- in region I there is a spherically-symmetric shell of small (but non-negligible!) mass radially falling into the blackhole
- in finite proper time it reaches singularity via region II
- say, we neglect gravitational waves
What's going to happen in region III in this case? Since I and III are connected via singularity in I and IV, it would seem that perturbation of singularity by the infalling shell should "propagate" (not casually, ofcourse!) to III. So for every motion in I there should be a corresponding motion in III meaning these regions are not independent?