Why singularities do not exist

  • Context: Graduate 
  • Thread starter Thread starter Dmitry67
  • Start date Start date
  • Tags Tags
    Singularities
Click For Summary

Discussion Overview

The discussion centers around the nature of singularities in the context of black holes and Hawking radiation, exploring the implications of observer-dependence in general relativity and the behavior of radiation near apparent horizons. The scope includes theoretical considerations and conceptual clarifications related to black hole physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the intensity of Hawking radiation as perceived by a freely falling observer, suggesting that it may be significant despite being red-shifted.
  • Another participant proposes that the singularity is obscured by a 'cloud' of Hawking particles, leading to the idea that the singularity may not exist in a conventional sense due to this blurring effect.
  • There is a discussion about the observer-dependence of the concept of 'particles,' with some participants suggesting that Hawking radiation is not observable by freely falling observers, while others speculate that they may experience a different type of radiation related to their own apparent horizon.
  • One participant challenges the claim that Hawking radiation is invisible to freely falling observers, indicating a disagreement on this point.

Areas of Agreement / Disagreement

Participants express differing views on the visibility of Hawking radiation to freely falling observers, with some asserting it is not observable while others suggest an alternative perspective. The discussion remains unresolved regarding the implications of these differing viewpoints on the existence of singularities.

Contextual Notes

Participants acknowledge the complexity of the concepts involved, including the dependence on the definitions of horizons and the nature of particles, which may contribute to the ongoing debate.

Dmitry67
Messages
2,564
Reaction score
1
I posted it in SR/GR but probably it really belongs here:

I am looking at the way how Hawking radiation is derived:
http://en.wikipedia.org/wiki/Hawking_radiation

Where can I find more info about it? (for amaters like me)

Formula for the Unruh temperature gives an infinite temperature at the horizon.
At the same time AFAIK the apparent horizon recedes in front of the falling observer.
Also, is my assumption correct that observer sees radiation from an apparent horizon, not from an absolute one?
The Hawking radiation looks very intensive but extremely red-shifted by the gravitation. Like almost infinity devided by almost infinity.

So I wonder how intensive the Hawking radiation is for the freely falling observer.

I can explain my motivation. Non red-shifted Hawking radiation is very intense. So when observer approaches the singularity, singularity is always hidden behind the apparent horizon. However, the horizon it covered with a cloud of hawking particles. These particles (in a frame of a falling observer) are emitted from the horizon but then fall back into the singularity together with the observer.

But the singularity of mass M is represented with the mass of the matter inside the apparent horizon S and the 'cloud' C, M=S+C

While C is almost negligible far from the singularity, it is quite possible that C>S close to it. But then singularity itself does not exist because the cloud 'blurs' the singularity and flattens space-time.
 
Physics news on Phys.org
Dmitry67 said:
I posted it in SR/GR but probably it really belongs here:



I can explain my motivation. Non red-shifted Hawking radiation is very intense. So when observer approaches the singularity, singularity is always hidden behind the apparent horizon. However, the horizon it covered with a cloud of hawking particles. These particles (in a frame of a falling observer) are emitted from the horizon but then fall back into the singularity together with the observer.

But the singularity of mass M is represented with the mass of the matter inside the apparent horizon S and the 'cloud' C, M=S+C

While C is almost negligible far from the singularity, it is quite possible that C>S close to it. But then singularity itself does not exist because the cloud 'blurs' the singularity and flattens space-time.

So your saying that for the falling observer the photons in the cloud are not observed as they fall into the singularity? But they remain outside the apparent horizon? I'm confused!
 
No, no.

At first, as it is well known, the very notion of the 'particle' is observer-dependent, for some observers particles can be real, for others they are virtual, for some observers space is vacuum, for others it is not.

For example, Hawking radiation observed for the outside observer is insivible for the freely falling observer.

I speculate that however freely falling observer observer ANOTHER type of hawking radiation - for HIS apparent horizon (different observers do not agree on the position of the apparent horizon).

As observer falls into black hole, apparent horizon recedes in front of him. So for the falling observer horizon is 'smaller' and emits much more radiation then for an observer 'at infinity'
 
Dmitry67 said:
For example, Hawking radiation observed for the outside observer is insivible for the freely falling observer.

This isn't true.
 

Similar threads

  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 42 ·
2
Replies
42
Views
15K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 17 ·
Replies
17
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K