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There is a treatment of lowering a string through a Rindler horizon here, (which contains a brief discussion on the extent to which the approximation is representative).


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Yes, you are taking the reversal thing too seriously. If you used Kruskal-Szekeres coordinates then those coordinates don't flip from timelike to spacelike. The flip is just because you chose bad coordinates. If you had flat boring Minkowski spacetime you could pick a coordinate system where a coordinate flips from spacelike to timelike across some surface. ...


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Density here is a bit misleading. For example density of galaxy cluster is low because there is so much space between it. It does not mean all the material inside has low density.. We cannot observe beyond Event horizon, so we use diameter of event horizon to measure volume. Actual matter will be in a smaller volume. To understand why large objects need ...


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You have to consider the singularity and event horizon. By observing the orbits of nearby planets and such, we can calculate the approximate mass of the black hole, and thus where the singularity is. This then further gives us the Schwarzschild radius; $R_{Schwarzschild}=\frac{2GM}{c^{2}}$ This defines the event horizon, thus allowing us to then calculate ...


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No, and certainly not by the mechanism you describe. The "orbits" of electrons around nuclei are structures created by the electromagnetic force. This force is mediated by photons, which cannot pass out of the event horizon by definition of the event horizon. So even in the highly implausible scenario in which an atomic structure existed within a black ...


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The field of quantum black holes is an hot topic of research right now, and the firewall proposal is still being debated. I have the feeling that no one really take the proposal seriously. By saying this I don't mean that it was a bad paper, on the contrary it's a nice thought experiment that forced us to think even more about the black hole information ...


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According to the cosmic censorship hypothesis all singularities are assumed to be behind horizons. This is not the same as saying "all horizons contain a singularity". The black hole solutions to Einstein's equations (which contain singularities) are all stationary, vacuum spacetimes. Stationary means that the spacetime does not explicitly depend on time. ...


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Technically/mathematically correct answer Here's an example of a black hole that is technically inside another black hole: the maximally extended Reissner-Nordstrom solution. In this case, what we mean by being "inside" the black hole is that the event horizon for one black hole is completely to the future of the other (see below for why this isn't ...



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