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That's not quite right, we do know what black holes are made up of: the remains of a star. Well, if they are reasonably small they are made out of the remains o
by SiempreViernes 7y ago
That's not quite right, we do know what black holes are made up of: the remains of a star. Well, if they are reasonably small they are made out of the remains of a star, if they are too big they can contain the remains of lots of stars and also gas, dust and maybe bits of planets, but exactly how we get the biggest black holes isn't clear.
The issue is rather that we don't know what all that star stuff becomes once it goes into the black hole, though there are theories. The problem is that the defining feature of a black hole, its even horizon, by necessity means there is no way of knowing what theory is correct since nothing happening inside is supposed to matter to us.
So before we can make any real progress on the interior of black holes we thus need to figure out exactly in what sense the event horizon leaks information, if it does.
In contrast, while we don't really know what happens to matter inside a neutron star, its surface remains visible to us and so we have been able to discard many different theories about what goes inside it. There is still debate about the precise equation of state, which correspond to different internal structure the various models represent and so different ideas of how a neutron star is made up.
Honestly, I don't know how much difference there are between the various models, but pretty crazy sounding ideas are still popping up, so there must be at least some space left.
- sidcool 7y agoThanks, this was informative. There are a lot of unknowns about black holes, and perhaps far in the future we will come to know as we fly by one such.
- posterboy 7y agoI once figured, could most massive stars have a black hole at the center? With thr crazy time dilations around a BH, I imagine the implosion would capture the escaping image of the prior star. I imagine a microscopic black hole at the core of thessun that immediately evaporates, but immediately looks like an eternity for us
- SiempreViernes 7y agoNo, you need something releasing a lot of energy in the middle of a star, otherwise it collapses down on itself and stops being a star, the event horizon doesn't provide any supporting pressure. Also, the process that compresses matter to the point it collapses to a black hole is very destructive; there is no reasonable way to form a black hole in the middle of the star.
- yaks_hairbrush 7y ago> The issue is rather that we don't know what all that star stuff becomes once it goes into the black hole, though there are theories. The problem is that the defining feature of a black hole, its even horizon, by necessity means there is no way of knowing what theory is correct since nothing happening inside is supposed to matter to us. Right. As far as "an observer at infinity" is concerned, all that in-falling matter gets asymptotically closer to the event horizon and never crosses it. One way to reframe the situation which I quite like: Black holes have no insides.
- theandrewbailey 7y ago> So before we can make any real progress on the interior of black holes we thus need to figure out exactly in what sense the event horizon leaks information, if it does. So we need to find the Meltdown/Specter-like vulnerabilities of black holes? I wonder how many problems that would cause the universe.