Hawking Radiation Inside a Black Hole: Theory & Possibilities

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Discussion Overview

The discussion revolves around the concept of Hawking radiation and its implications within black holes, particularly focusing on the nature of event horizons and the possibility of radiation emission from regions inside the event horizon. Participants explore theoretical predictions, analogies, and the conditions under which Hawking-like radiation might occur.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant suggests that black holes could emit Hawking radiation from within their event horizons, proposing that as one approaches the singularity, the temperature of this radiation could approach infinity.
  • Another participant counters that the definition of a black hole inherently includes the presence of an event horizon, arguing that the initial premise is flawed.
  • A different viewpoint introduces the idea of Hawking-like radiation produced by spinning black holes due to quantum fluctuations outside the event horizon, referencing earlier theoretical work by Zeldovich.
  • Some participants challenge the assertion that a boundary (event horizon) is unnecessary for the emission of radiation, arguing that Zeldovich's predictions rely on the presence of a horizon.
  • There is a discussion about the analogy between a spinning black hole and a spinning metal sphere, with some participants asserting that the analogy necessitates the existence of an event horizon.
  • One participant emphasizes the role of tidal forces and gravitational differentials within a black hole, suggesting these could contribute to radiation emission as one approaches the center.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the necessity of an event horizon for Hawking radiation and the validity of conjectures about radiation emission from within black holes. The discussion remains unresolved, with no consensus reached on these points.

Contextual Notes

Participants highlight limitations in the arguments presented, including the dependence on definitions of black holes and the speculative nature of some claims regarding radiation emission from inside black holes.

PSR1257II
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TL;DR
Can Hawking radiation be emitted inside Event Horizon and prevent point-singularity?
It is known theoretical prediction that Black Holes must emit radiation "... its temperature and surface gravity are proportional to its mass divided by its area" (Kip Thorne). This is applied to Event Horizon (rg).

But one can imagine inner Black Hole (e.g. inside r' < rg), it does not have Event Horizon in common sense (e.g. radiation created at r' must inevitably fall back) but still can? emit Hawking radiation. As r'->0 this radiation must have Temperature -> infinity (see above), therefore making superhot and finite (not point) singularity.

?
 
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PSR1257II said:
one can imagine inner Black Hole (e.g. inside r' < rg), it does not have Event Horizon in common sense

No, one can't. The definition of a black hole is that it has an event horizon.

Your question is meaningless because it is based on a mistaken premise.
 
I believe it is important to note that there is another type of Hawking-like radiation - emission made by spinning Black Hole out of quantum fluctuations outside of Event Horizon. E.g. there is no particular need for "boundary" (Horizon) to split particle-antiparticle.

This theoretical prediction was made prior Hawking's discovery in 1973 by Zeldovich.
 
PSR1257II said:
. E.g. there is no particular need for "boundary" (Horizon) to split particle-antiparticle

Have you read Hawing's paper? That is not his argument.
 
PSR1257II said:
emission made by spinning Black Hole out of quantum fluctuations outside of Event Horizon. E.g. there is no particular need for "boundary" (Horizon) to split particle-antiparticle.

You are incorrect that there is no need for a "boundary" (Horizon). Zeldovich's prediction does depend on the presence of a horizon. His discovery amounted to the claim that a spinning black hole emitting gravitational waves due to quantum fluctuations is analogous to a spinning metal sphere emitting electromagnetic waves due to quantum fluctuations. The hole's horizon is analogous to the boundary of the metal sphere.

https://en.wikipedia.org/wiki/Superradiance
 
PeterDonis said:
You are incorrect that there is no need for a "boundary" (Horizon). Zeldovich's prediction does depend on the presence of a horizon. His discovery amounted to the claim that a spinning black hole emitting gravitational waves due to quantum fluctuations is analogous to a spinning metal sphere emitting electromagnetic waves due to quantum fluctuations. ...

https://en.wikipedia.org/wiki/Superradiance

"It is also sometimes described as the consequence of an "effective" field differential around the body (e.g. the effect of tidal forces)." (c) Wiki

Can you please be exact about where the need for boundary (Horizon) raises? I do see only need for differential (tidal force) and strong gravitational field.

Back to original conjecture - inside Black Hole there is differential between different points respect to center (tidal force) and it just grows as r -> 0.
 
PSR1257II said:
Can you please be exact about where the need for boundary (Horizon) raises?

Zeldovich's argument wasn't exact. He was just drawing an analogy between a spinning metal sphere and a spinning black hole. In the analogy, the hole's horizon was analogous to the surface of the sphere. Since the analogy is all we have, we can't just eliminate the hole's horizon because then there is no analogy.
 
PSR1257II said:
inside Black Hole there is differential between different points respect to center (tidal force) and it just grows as r -> 0

And in the spacetime where this is the case, there is an event horizon. The two things go together.

PSR1257II said:
Back to original conjecture

Your conjecture is personal speculation and is off limits for PF discussion. Thread closed.
 

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