Neglecting evaporation, it's a lot closer to Yen Chin Ong's results (and those he cites, especially Christodoulou and Rovelli [2]) than most of the comments thr

Neglecting evaporation, it's a lot closer to Yen Chin Ong's results (and those he cites, especially Christodoulou and Rovelli [2]) than most of the comments throughout this discussion, in that with a careful choice of time coordinate a spacelike spherical sector of a Schwarzschild black hole could evolve roughly similarly. Of course, one has enormous freedom to choose spacelike hypersurfaces through a Schwarzschild black hole, so such a result is not especially interesting without some sort of uniqueness proof for the idea, and I don't think that's achievable. (cf [2]). I'm also not sure this is what GP has in mind. - -- [1] https://arxiv.org/abs/1503.08245 https://arxiv.org/abs/1503.08245 (§ 2) (simpler overview: https://www.kth.se/profile/ycong/page/the-interior-volumes-of-black-holes https://www.kth.se/profile/ycong/page/the-interior-volumes-o... ) [2] https://arxiv.org/abs/1411.2854 https://arxiv.org/abs/1411.2854 (§ IV)