Black hole - between horizon and singularity

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SUMMARY

The discussion centers on the nature of the space between a black hole's event horizon and its singularity. It is established that this region is predominantly a vacuum, although some participants argue that there may be non-vacuum regions occupied by matter falling into the black hole. The conversation touches on concepts such as vacuum energy and the fuzzball string theory, highlighting the complexity of understanding what occurs beyond the event horizon. Participants emphasize that while light can enter a black hole, it cannot escape, complicating our understanding of the internal dynamics.

PREREQUISITES
  • Understanding of black hole physics, specifically event horizons and singularities
  • Familiarity with vacuum energy concepts in quantum physics
  • Basic knowledge of string theory, particularly the fuzzball proposal
  • Awareness of quantum gravity models and their implications on spacetime geometry
NEXT STEPS
  • Research the implications of vacuum energy in black hole physics
  • Study the fuzzball string theory and its relevance to black hole information paradox
  • Explore quantum gravity models and how they relate to spacetime geometry
  • Investigate the observational limits of black holes and the nature of light within them
USEFUL FOR

Astronomers, physicists, and anyone interested in advanced concepts of black holes and quantum mechanics, particularly those with a foundational understanding of physics and mathematics.

arlesterc
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What occupies the space between a black hole's event horizon and the singularity? Stuff hurtling to the singularity? Vacuum?
 
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arlesterc said:
What occupies the space between a black hole's event horizon and the singularity? Stuff hurtling to the singularity? Vacuum?
Actually, nobody really knows. What goes on beyond the event horizon stays beyond the event horizon.
 
arlesterc said:
What occupies the space between a black hole's event horizon and the singularity?

Nothing. A black hole is a vacuum, i.e., it is empty space everywhere.
 
We can't see into a black hole. Whatever is in the black hole can't see us. That part seems to be clear to me. However as the surface of a black hole is conjectured to have all the bits in the black hole - in fact is the limit of the bits in the black hole - it seems there is something in the black hole other than vacuum. Stuff goes into and disappears to us but that doesn't mean it isn't there in some form. And it falls toward the singularity from my understanding. As the black hole is constantly absorbing stuff it seems a lot of stuff is making this trip. So even though the form this stuff takes as it hurtles to the singularity is not observable to us it seems to be something. So the black hole doesn't seem to be merely vacuum. I can see however that the black hole could have vacuum and vacuum energy - I don't see a reason why not - feel free to give me theories for or against this proposition. And given that,I can see that the stuff going into it could add energy to the vacuum. That it would do only that however is a little harder for me to understand as I feel from all that I have read that something is hurtling to the singularity/adding to the mass of the black hole. Again feel free to persuade me otherwise. Links are good as direct explanation - but they need to be at 'interested laymen with some physics and math background' level. Thanks for any further time with this.
 
arlesterc said:
We can't see into a black hole.

Correct.

arlesterc said:
Whatever is in the black hole can't see us.

Incorrect. Light can travel into the black hole just fine, so observers inside can see things outside. They just can't send light signals back out.

arlesterc said:
as the surface of a black hole is conjectured to have all the bits in the black hole - in fact is the limit of the bits in the black hole - it seems there is something in the black hole other than vacuum.

If something falls into the hole, obviously there is a tiny non-vacuum region occupied by that something. But the rest of the inside is still vacuum.

The (speculative) point you seem to be unaware of is that, in the quantum gravity models you are referring to, spacetime geometry itself has bits of information associated with it, even if it is vacuum, i.e., even if there is no matter or energy present. So the "bits" stored at the horizon are storing information about the (vacuum) spacetime geometry inside.
 

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