Why singularities and not exclusion?

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Discussion Overview

The discussion centers around the nature of singularities in black holes and the implications of quantum mechanics (QM) versus general relativity (GR). Participants explore the tension between these theories, particularly in the context of the Pauli exclusion principle and the behavior of matter under extreme gravitational conditions.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants question the assumption that gravity can create infinitely dense mass, suggesting that the Pauli exclusion principle should prevent this.
  • Others argue that the singularity in black holes is a result of applying only general relativity and that incorporating quantum theory leads to unresolved questions about what occurs inside a black hole.
  • A participant expresses skepticism about singularities and wormholes, advocating for a quantum explanation instead, and references a recent paper by Leonardo Modesto that claims singularities do not exist in a quantized version of GR.
  • One participant notes that the term singularity indicates a breakdown in the mathematical model rather than a definitive statement about physical reality.
  • Another participant mentions that degeneracy pressure, a consequence of the exclusion principle, is accounted for in the equations of state for compact objects, but acknowledges that gravity can ultimately dominate in massive objects leading to black holes.

Areas of Agreement / Disagreement

Participants express differing views on the validity and implications of singularities in black holes, with no consensus reached on the resolution of these issues. Some support the idea that quantum mechanics may provide alternative explanations, while others uphold the traditional view based on general relativity.

Contextual Notes

There are unresolved questions regarding the integration of quantum mechanics with general relativity, particularly in extreme conditions such as those found in black holes. The discussion highlights the limitations of current models and the need for further exploration of these concepts.

Gonzolo
Hi, everybody always talks about black holes being singularities, but why does everyone always take GR's side and neglect Pauli's exclusion principle? Why do people assume gravity is stronger?

Suppose I decide that gravity can't make mass infinitely dense because particles can't have the same state. What's wrong with that?
 
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The singularity inside a black hole is a result of using only general relativity. When quantum theory is taken into account, there is no known sensible solution. In other words nobody really knows what happens inside a black hole.
 
I know no one knows, but people still always talk about singularities. Those are the answers that are seen everywhere, and I understand that, but for the time being, I choose that singularities, and wormholes etc. are completely absurd, non-satisfactory, old news, and that there has to be a quantum explanation. What I do not see is what exactly happens when we take into account QM inside a black hole, how does QM fail? What are the non-sensible solutions?
 
Gonzolo said:
I know no one knows, but people still always talk about singularities. Those are the answers that are seen everywhere, and I understand that, but for the time being, I choose that singularities, and wormholes etc. are completely absurd, non-satisfactory, old news, and that there has to be a quantum explanation. What I do not see is what exactly happens when we take into account QM inside a black hole, how does QM fail? What are the non-sensible solutions?

this year Leonardo Modesto, a student of Rovelli at Univ. Marseille, applied QM to black holes and saw that the singularity goes away.
it is not real.
in a quantized version of GR it does not exist.
Modesto paper is online at arxiv, just search by name Modesto

http://arxiv.org/

http://arxiv.org/find/grp_physics/1/au:+modesto/0/1/0/all/0/1
 
Last edited:
okay...here's a clue.


Look for the jets :confused: :smile:
 
marcus said:
this year Leonardo Modesto, a student of Rovelli at Univ. Marseille, applied QM to black holes and saw that the singularity goes away.
it is not real.
in a quantized version of GR it does not exist.
Modesto paper is online at arxiv, just search by name Modesto

http://arxiv.org/

http://arxiv.org/find/grp_physics/1/au:+modesto/0/1/0/all/0/1

Good! I hope Modesto is right! I'm rooting for QM! Woohoo!
 
Gonzolo said:
Hi, everybody always talks about black holes being singularities, but why does everyone always take GR's side and neglect Pauli's exclusion principle? Why do people assume gravity is stronger?

Suppose I decide that gravity can't make mass infinitely dense because particles can't have the same state. What's wrong with that?

The exclusion principle is not neglected, it is taken into account in the equation of state, leading to degeneracy pressure. This has been understood since the work of Chandrasekar in th 1930's and is central to the calculation of the properties of compact objects such as white dwarves or neutron stars. However, given a sufficiently massive object gravity will always win out in the end, leading to a black hole.
 
Thank you very much, Chronon. I will have to review this degeneracy pressure. It does ring a bell.
 
Permit me to add that the term singularity is used to describe where the mathematical model breaks down. Physical reality does not always respect our version of the laws of mathematics.
 

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