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If a black hole isn't "fed" by attracted matter, it disappears someday. But how is that even possible? What happens with the mass at its singularity? It can't just disappear or am I wrong with something? Where does the mass disappear to and how is it possible?

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The mass (equivalently energy) is radiated away as Hawking radiation.

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  • $\begingroup$ But what happens with the matter from the singularity? $\endgroup$
    – user30007
    Feb 6, 2020 at 16:28
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    $\begingroup$ @user30007 Hypothetically, it's converted to energy and radiated away, as this answer says. I wrote "hypothetically" because Hawking radiation has never been observed. $\endgroup$ Feb 6, 2020 at 16:50
  • $\begingroup$ @DavidHammen, shouldn't that be, "Theoretically,...?" $\endgroup$ Feb 6, 2020 at 18:18
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    $\begingroup$ @user30007 The black hole singularity is also theoretical, and (hopefully) a quantum gravity theory will replace it. But in standard GR, a black hole singularity isn't like an object in space. Firstly, a singularity never exists in the past of any observer. And as described here "A singularity in GR is like a piece that has been cut out of the manifold. It's not a point or point-set at all". $\endgroup$
    – PM 2Ring
    Feb 6, 2020 at 23:54
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    $\begingroup$ @SolomonSlow - No, it should not. People abuse the word theory so much that it now has come to mean "a wild guess made after having chugged one too many margaritas." A scientific theory is the pinnacle of science. A hypothesis: Not so much, and least not yet. Hawking radiation is a scientific hypothesis rather than a scientific theory. This hypothesis that has a solid basis in both general relativity and quantum mechanics, but it remains hypothetical. $\endgroup$ Feb 7, 2020 at 4:31

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