Regular black holes are black holes (regions of spacetime bounded by an event horizon) without any singularity. Black hole spacetime's that allow observers to avoid singularities (because the holes lack them or because they are "timelike") lead to new universes. Such as the Kerr metric , an ideal rotating hole. A regular black hole prison cell? Disclaimer: real black holes are thought to have, for all practice purposes, deadly unavoidable singularities in them, and making a regular hole probably requires non-existent "exotic matter". Can you avoid new universes in regular hole spacetimes? Let's try to build a "black hole Earth" spacetime: Far from Earth/the black hole, gravity is approximately Newtonian. For both Earth and the hole, gravity initially rises when you get closer. As you approach the black hole horizon, the acceleration needed to hover goes to infinity. So you are forced inward once you reach the horizon no matter how strong your rocket is. However, the spacetime stays smooth. Once you get to Earths core, gravity starts decreasing . For the black hole, you would reach an inner horizon. Inside the inner horizon you can again hover. In both cases this happens because you are not in a vacuum; the stress-energy tensor is nonzero. Near the center, gravity smoothly goes to zero for both Earth and the black hole. If you throw a rock at a low speed, and it could go though whatever material was present, it will bounce back and forth. You are trapped with no universe to escape into. Can such a black hole spacetime exist, given the right kind of exotic matter? Or do regular holes need new universes?