Gravitation and Information, BH paradox

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Discussion Overview

The discussion revolves around the relationship between gravitational waves and information, particularly in the context of black hole (BH) information paradoxes. Participants explore whether information emitted through gravitational waves can be considered as part of the information about a system, especially when a body falls into a black hole and during the black hole's evaporation process.

Discussion Character

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

Main Points Raised

  • Some participants question whether information carried by gravitational waves emitted from a system counts as information about that system.
  • There is a proposal that when a body falls into a black hole, it emits gravitational waves that carry information, and a later reply seeks clarification on this point.
  • One participant asks about the maximum amount of information carried away by gravitational waves and whether information can be emitted before the black hole evaporates.
  • Another participant argues that according to classical and semiclassical gravity, once gravitational waves are trapped inside a black hole, they cannot escape, contributing to the information paradox.
  • Some participants express skepticism about the emission of information from a black hole before it evaporates, citing classical and semiclassical gravity principles.
  • There is a comparison made between the BH information paradox and the grandfather paradox, suggesting that both arise from assumptions about the nature of time.
  • One participant discusses the idea that empty space in general relativity can carry information, raising questions about the ratio of information contained in matter versus that in space.
  • Concerns are raised regarding the validity of claims about black holes and the need for rigorous mathematical support for extraordinary claims.
  • There are challenges to the assertion that black holes do not disappear in finite time to observers outside the event horizon, with requests for references to support this claim.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the emission of information from black holes and the implications of gravitational waves. The discussion remains unresolved, with no consensus reached on several key points.

Contextual Notes

Some claims rely on classical and semiclassical gravity frameworks, which may not account for all interpretations of gravitational phenomena. The discussion includes references to specific theories and models, but these are not universally accepted or agreed upon.

Dmitry67
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When (almost any) system emits gravitational waves, does information carried by these waves also 'counted' as an information about a system?

In case of BH informational paradox, when BH dissapears, we get not only Hawking radiation, but also information encoded in the gravitational waves of all bodies fell into BH? Right or wrong?
 
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Ohh, interesting question. I'm interested to see an answer to this as well.
 
Dmitry67 said:
When (almost any) system emits gravitational waves, does information carried by these waves also 'counted' as an information about a system?

Yes.

but also information encoded in the gravitational waves of all bodies fell into BH?

What do you mean by this part? Could you re-word, I'm not entirely sure what you're asking.
 
Say, we throw a body into BH.
The falling body would emit Gwaves.
What maximum amount of information is carried away by these waves?
What amount of information is extracted indirectly (because falling body changes the position of the absolute horizon, so it changes the outcomes for ome events)?
Is it possible that information about a body is emitted (to the external world) even before BH evaporates?
 
Dmitry67 said:
In case of BH informational paradox, when BH dissapears, we get not only Hawking radiation, but also information encoded in the gravitational waves of all bodies fell into BH? Right or wrong?
According to classical and semiclassical gravity, this is wrong. Namely, once the gravitational waves become trapped inside the black hole, these two theories do not allow gravitational waves to escape out of the black hole. And this is why there is an information paradox in the first place.
 
Dmitry67 said:
Is it possible that information about a body is emitted (to the external world) even before BH evaporates?
No, according to classical and semiclassical gravity.
 
In my opinion, the solution of the BH information paradox is essentially the same as the solution of the grandfather paradox (related to closed causal curves). Both paradoxes arise due to a tacit assumption that time is substantially different from space by having a property of "flowing". When, in spirit of the theory of relativity, one explicitly removes that assumption, then both paradoxes disappear trivially. For more details see
http://xxx.lanl.gov/abs/gr-qc/0403121 [Found.Phys.Lett. 19 (2006) 259-267]
http://xxx.lanl.gov/abs/0905.0538 [Phys.Lett.B678:218-221,2009]
http://xxx.lanl.gov/abs/0912.1938
 
Why?
If parts of a body are moving with acceleration (like blood in our veins) then they emit gravitational waves. These waves carry away some information about the body.

You can argue that these waves are so weak, that only very small number of gravitons go away, so the information is very limited. But it is based on the assumption that gravity is quantified exactly as all other forces.
 
Dmitry67 said:
Why?
If parts of a body are moving with acceleration (like blood in our veins) then they emit gravitational waves. These waves carry away some information about the body.
Maybe I was not clear. I am not saying that it will not be emitted. I am saying that some of it will be emitted even AFTER BH starts to evaporate.
 
  • #10
Dmitry67 said:
In case of BH informational paradox, when BH dissapears...

A black hold does not disappear in finite time to any observer external to the event horizon much to the disappointment of many. In some circles this means never, in proper time. Given this new found information about information, where does this leave your apparent paradox, and the horn-locked pair of so-callled experts, Hawking and Susskin on something that never happens until hell freezes over and the Universe no longer exists?
 
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  • #11
Understood.

But just thinking - forget about Black Holes... In GR empty space can carry information. Objects emit GR waves since the beginning of the universe. Space is filled with some informational waste - undetectable GR waves with very low amplitudes.

What is a ratio of information contaned in matter vs in space?
 
  • #12
Dmitry67 said:
Understood.

But just thinking - forget about Black Holes... In GR empty space can carry information. Objects emit GR waves since the beginning of the universe. Space is filled with some informational waste - undetectable GR waves with very low amplitudes.
]
I don't know. However, I'm not so sure, as those who are gainfully employed looking for gravitational waves, that gravity waves should contain classical information---stuff measurable without interference measurement such as found in the Bohm-Arharanov effect. They've failed for several decades in this endeavor. That is, I think they need to find real jobs at mc donalds flipping burgers. Poor saps.

If they had a super-massive star dancing around we could have seen some positive reports on gravitational wave interference phenomena--maybe.
 
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  • #13
Phrak said:
A black hold does not disappear in finite time to any observer external to the event horizon
Do you have an argument for that strong claim?
 
  • #14
Phrak said:
A black hold does not disappear in finite time to any observer external to the event horizon much to the disappointment of many

Demystifier said:
Do you have an argument for that strong claim?

This is a fair challenge. You might help out in deciding this if you like. If we are interested in objectivity, rather than winning arguments, we might decide my odd-sounding claim one way or the other. This claim, which seems obvious to me--which I've only concluded without mathematical rigor--might be found false.

Rather then deciding this for the entire class of black holes, I suggest first looking first at the Schwarzschild metric to see what can be said of Hawking radiation propagating to finite distance in this reduced subset of black holes, to see what can be learned.

To this end, I've been looking at the path integral in the Schwarzschild.
 
  • #15
Phrak said:
This is a fair challenge. You might help out in deciding this if you like. If we are interested in objectivity, rather than winning arguments, we might decide my odd-sounding claim one way or the other. This claim, which seems obvious to me--which I've only concluded without mathematical rigor--might be found false.

Rather then deciding this for the entire class of black holes, I suggest first looking first at the Schwarzschild metric to see what can be said of Hawking radiation propagating to finite distance in this reduced subset of black holes, to see what can be learned.

To this end, I've been looking at the path integral in the Schwarzschild.
Let me just quote Carl Sagan:
"Extraordinary claims require extraordinary evidence."
 
  • #16
Demystifier said:
Let me just quote Carl Sagan:
"Extraordinary claims require extraordinary evidence."

I agree. I find the common class of claims made of black holes extraordinarily reckless. These, traded both on this forum and swapped nearly everywhere, have been proffered without support, but with extraordinary faith, comforted from criticism by a like-minded audience.
 
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  • #17
Phrak said:
A black hold does not disappear in finite time to any observer external to the event horizon much to the disappointment of many.

I don't think this is true. Can you provide a reference to a book or paper that makes an argument to this effect?
 
  • #18
Bcrowell, have you noticed that I asked him the same question? And he answered it. It's up to you to see if his answer will satisfy you or not, but there is no point in asking him the same question again.
 

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