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When a black hole destroys things until they are smaller than molecules, where does it go and what happens when it clogs up?

Qmechanic
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Dru Crichton
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  • I think this needs a simple explanation of black holes, Hawking radiation and possibly the information loss paradox. – innisfree Apr 29 '13 at 21:07
  • What happens with the matter after it went into a black hole? Well, we never see it falling in. From the reference of the infalling matter, no one knows. – Calmarius Apr 29 '13 at 21:21
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    I think this is a duplicate of http://physics.stackexchange.com/q/26704/22494 and we just don't know. What general relativity tells us doesn't jive with what Quantum Mechanics tells us. – Brandon Enright Apr 29 '13 at 21:35

2 Answers2

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where does it go and what happens when it clogs up?

In the context of an ideal, static black hole in general relativity, world lines end at the singularity. Consider the diagram below:

enter image description here

This is the Schwarzschild geometry in Kruskal–Szekeres coordinates. In these coordinates, it is clear that there is no place or time that the entities falling into the black hole go; the matter and energy that fall into the hole cannot avoid the singularity, i.e., the end of existence.

The regions of the diagram "above" the upper zigzag curve (the future singularity) and "below" the lower zigzag curve (the past singularity) are not part of the spacetime; there are no events in those regions of the diagram.

Alfred Centauri
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Your question touches on the quantum behaviour of black holes, a subject with fundamental, unsolved problems.

Classically, black holes cannot emit light, because light cannot escape their strong gravitational fields. The gravity is so strong that any matter that fell into a black hole would be torn into fundamental particles, and become part of the black hole. The black hole would become more massive and bigger.

Remarkably, Hawking showed that at the quantum level, black holes were like objects with a temperature that cooled by emitting light (electromagnetic radiation). Formally, he recognized an analogy between black holes and thermodynamics. Hawking showed that particle-antiparticle pairs would produced on the edge (event-horizon) of black holes. The particle would escape the black hole; the antiparticle would remain trapped. This escaping particle is Hawking radiation.

An important insight was that this Hawking radiation has no information content; if you throw an encyclopedia into a black hole, you cannot find any of its information from the Hawking radiation. In contrast, if you burn an encyclopedia, you can in principle find its contents from the distribution of the smoke etc. Black holes appear to destroy information.

This is considered to be a paradox, because information ought not to be destroyed. The ultimate fate of black hole is that it will radiate away via this Hawking radiation. Some believe that the information of, say, any encyclopedias thrown into the black hole would remain in the black hole until this moment but one problem is indeed that the black hole would be clogged up; it wouldn't have any room for more information.

Others say that information is irreversibly destroyed by the black hole. Others that there is a firewall at the edges of black holes. But no one knows for sure.

innisfree
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