Black Holes and Quantum Field Theory

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Discussion Overview

The discussion revolves around the relationship between black holes and quantum field theory (QFT), particularly focusing on concepts such as the No Hair Theorem, spin quantization, and the nature of black holes at quantum scales. Participants explore theoretical implications and classifications of black holes in the context of both general relativity (GR) and quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that the No Hair Theorem implies a connection between quantum particles and black holes, particularly in the context of microscopic black holes being quantized by mass (M), charge (Q), and angular momentum (L).
  • Another participant clarifies that the Schwarzschild solution is a GR solution and does not imply a quantum-mechanical solution, though acknowledges the mathematical aspect of a black hole having zero angular momentum.
  • There is a discussion about the possibility of black holes being classified as bosonic due to their ability to have zero angular momentum, with a suggestion to associate angular momentum with spin.
  • One participant raises the issue of whether the metric used in GR is applicable at quantum scales, questioning the relevance of classical solutions in quantum contexts.
  • Another participant points out that black holes typically form with some angular momentum, making the existence of a zero angular momentum black hole highly unlikely, thus suggesting they would more likely be Kerr black holes.
  • There is a mention of the potential for black holes to be classified as fermionic or bosonic, depending on additional particles that might be added to them.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the No Hair Theorem, the applicability of GR metrics at quantum scales, and the classification of black holes as bosonic or fermionic. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants note limitations regarding the applicability of classical solutions to quantum scenarios and the uncertainty surrounding the existence of black holes with zero angular momentum.

jbcool
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Now, I must preface this by saying that my understanding of QFT is limited, and my understanding of GR is even more so. Nevertheless, I was reading about the No Hair Theorem, and it seemed to me to be suggestive of the indiscernibility of Quantum Particles. Obviously, for a macroscopic black hole, this is merely analogy, but for a microscopic black hole, this isn't necessarily true. If a black hole can be quantized solely by M, Q, and L, then, on the microscopic level, it would make sense to have Q at the very least quantized. It also wouldn't be entirely out of the question to associate L with spin, since they are both intrinsic angular momenta. This would lead one to conclude that black holes must be bosonic since they can have 0 angular momenta (Schwarzschild BH). If it were some how possible to attribute a bosonic field to a black hole, it would make sense to describe it by the two coupling constants Q and M, and have a spin L. Is this logical, or is it too speculative.
 
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The Schwarzschild solution is a solution for GR, it does not imply that it is a quantum-mechanical solution.

Spin quantisation of black holes... I am sure there are publications about it, but I don't know any.
This is about charge
 
Thanks. I wasn't saying that the Schwarzschild solution was also a QM solution, merely that it shows a black hole can have 0 angular momentum.
 
It shows that there is a spacetime geometry with 0 angular momentum. But that is just a mathematical thing. We don't know if this solution (in GR) can exist in the universe.

I wouldn't expect BH to be fermions, but maybe they are? Or even something completely different, as the classification gets more complicated once we leave the classical 3 dimensions.
 
True. I guess a more pressing issue is whether the metric even applies at quantum scales. Still, it seems that the No Hair theorem is suggestive of a link between QM and GR.
 
In real life, black holes form from collapsing objects, and the odds of producing a hole with zero angular momentum is just that, essentially zero. In fact every black hole will have at least some angular momentum and therefore be Kerr rather than Schwarschild.

And as far as a black hole being bosonic or fermionic, all you have to do is drop one additional electron into the hole to make it the other one.
 

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