Hawking Radiation

Discussion in 'Physics & Math' started by The God, Mar 10, 2017.

  1. karenmansker HSIRI Banned

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    RJB: IMHO (H = humorous here): The anti-particle would surely traverse the EH via an 'anti-tunnel'! (HAHAHA!
     
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  3. The God Valued Senior Member

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    My opinion about HR is......there is no BH at all, so the question of HR does not arise.

    Having said that...you and exchemist raised two points....one is you were talking about export of energy from inside of EH, that does not happen even under HR regime. Other point was about why anti particle falls inside EH, some kind of preferential treatment. I stated that it is all probabilistic under QM. But you missed to note the finer and subtle difference, there is no preferential treatment to anti particle. Exchemist also raised the issue of energy release but that does not happen as the negative energy of particle reduces the equivalent mass.
     
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  5. RJBeery Natural Philosopher Valued Senior Member

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    This is a matter of interpretation. The escaping particle represents the exported information because the anti-particle presumably annihilates with a particle within the EH. It's not a sticking point for me, we can drop it, I just want a plausible explanation of the next:
    You appear to be hand-waving here. Just using the phrase "probabilistic under QM" does not resolve the issue. If there is no preferential treatment to the anti-particle then roughly 1/2 of the time the black hole will lose energy because an anti-particle has tunneled into it and the other half of the time the black hole will gain energy because a particle has tunneled into it and the pair-production anti-particle will escape to infinity.
     
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  7. The God Valued Senior Member

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    Good at least first point is covered.

    On the second point......the objection is so obvious, but what is being missed is probably the subtle point which Hawking is trying to make in his paper. Hawking gave this explanation to resolve the apparent contradiction with BH Area Theorem, he goes on to saying that particle-antiparticle scenario is not to be taken as literally happening. I take it differently QM fluctuations happen almost everywhere, but Hawking is associating it with BH gravity and thermodynamics of BH, so it is more than random creation of particle, specific to scenario near EH. You are trying to dismiss HR/BH/Paradox based on improbability of simplistic particle/anti particle functioning as suggested by him with a caution, with a purpose of understanding.

    I do not understand what his main theme is (because this particle antiparticle treatment or description is stated as quite sloppy and for lay people, even hawking warns that it is not to be taken literally), so first we must understand his real argument and then find fault. Since Rpenner is fan of this HR thing, may be he can better explain the real physics behind it with least use of semantics.
     
  8. Q-reeus Valued Senior Member

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    In an earlier thread by the same name, I raised a number issues wrt HR that never got a sensible response:

    1: For a typical stellar mass BH, standard picture has (eventually, after CMBR has enormously diluted from current ~ 2.7 K) a net outward flow of EM radiation i.e. photons - for the overwhelming portion of it's lifetime and mass. Only the tiniest final fraction of mass/lifetime is there appreciable massive particle/anti-particle generation. So, as photons are their own anti-particle, and always have positive energy E = hf, from whence this notion of negative energy quanta being swallowed so as to reduce the BH mass? An influx of always positive energy photons can only increase BH mass.

    2: Let's for now ignore 1 above, and suppose negative energy particles exist and are generated copiously just exterior to the BH EH. How could such negative mass/energy quanta do anything but be preferentially expelled, with only the positive quanta being gravitationally trapped and drawn in? Basically, a BH will appear to be a 'white hole' to negative energy quanta. Impossible to enter.

    For case 1, BH mass grows not shrinks, and simultaneously positive energy is radiated out. A kind of astrophysical perpetuum mobile. For case 2, BH mass again grows, but negative mass/energy is radiated out. Which 'balances the books' but in opposite sense to standard picture. Logically though, 2 can never kick in given 1. Or only by starting with a very low mass BH.

    Contrary to GR, gravity theories where horizons never form have no such conundrums to fret over.
     
  9. RJBeery Natural Philosopher Valued Senior Member

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    Praise the Lord! That makes three of us in this thread...

    Please Register or Log in to view the hidden image!

     
  10. Q-reeus Valued Senior Member

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    Right, but see my next post.
     
  11. Q-reeus Valued Senior Member

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    That first line in #45 looks to be repeated here. Evidently an intelligent and focused response to the glaringly obvious issues raised is asking too much of SF folks.
     
  12. The God Valued Senior Member

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    This preferential treatment part. I was looking around for the argument in favor of HR on this issue. The closest I came was...that for a standard uncharged non spinning BH the time becomes spatial inside the EH and tunnelling blah blah...I do not know how it helps in sucking (preferentially or with higher probability) the negative energy particle.
     
  13. Q-reeus Valued Senior Member

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    That is considered by GR specialists as nothing more than an artifact of formally extending Schwarzschild coordinates to beneath the EH and is absent in other coordinate charts e.g. Kruskal–Szekeres: https://en.wikipedia.org/wiki/Kruskal–Szekeres_coordinates

    An anomaly free theory e.g. Yilmaz gravity needs no such fancy transformation tricks and is regular everywhere (except for a very graceful asymptotic ride to a singularity without curvature blowup). Using a standard coordinate chart derived directly from the associated metric line element. But getting back to your bit about 'preferential treatment' of -ve energy particles - it's rendered moot by the content of #45 which you quoted in full but made no comment on my specific claims there.
     
  14. The God Valued Senior Member

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    Thats fine but..
    Then why the reference to this aspect in explaining negative energy particle getting sucked in?
     
  15. Q-reeus Valued Senior Member

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    What?! Entirely separate issues were being addressed. My explaining why your reference in #49 to time and space coordinates swapping inside EH is of no significance, such is purely a mathematical *artifact* of using Schwarzschild coordinates outside their generally accepted domain. Physics doesn't actually turn weird(er) than outside EH. Comprehende Amigo? If you wish to discuss what I was actually on about in #45 feel free to give it a try.
     
  16. The God Valued Senior Member

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    On the face of it, appears unrelated but please see the reference to the same by Hawking in his original paper, as linked by me in previous posts.


    Also please refer to....https://arxiv.org/pdf/1410.1486.pdf....this paper was supplied by Rpenner in Quantum Fluctuation thread (http://sciforums.com/threads/quantum-fluctuation-causal.159052/page-4) to justify his stand that Trans Planckian issue is settled. The extract of the paper is below..


    So this time like coordinate becoming a spatial coordinate inside EH appears to me a key for so what
    called preferential treatment to negative energy particle.
     
  17. Q-reeus Valued Senior Member

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    Well imo the entire reasoning in the last two passages quoted in #53 is erroneous and a consequence of accepting the GR mandated notion of a BH EH. Hawking's appeal to tunneling seems like a way to get around the fact that a locally positive 'particle' (photon overwhelmingly) just outside of EH cannot magically become negative energy wrt far outside simply by falling in. Since the trade between PE and KE is a conservative one at any elevation. Otherwise, one should expect any potential BH's mass to vanish in the process of forming. But collapsed stars don't wink out of existence.

    Stop working from the basic assumption of a Schwarzschild metric BH, and nonsensical arguments and conclusions that follow such will nicely vanish.
     
    Last edited: Mar 26, 2017
  18. The God Valued Senior Member

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    Well Hawking is pro GR.
    And mind you the paper has 9000+ citations
     
  19. Q-reeus Valued Senior Member

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    Do you think that means it should be trusted as Truth?
     
  20. The God Valued Senior Member

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    Not at all. But 9000+ ayes to a paper calls for some introspection not only on the physics around but on the herd mentality, if it is not a truth.

    As I said I am anti BH, so question of my supporting HR does not arise. I was just referring to what mainstream is.
     
  21. RJBeery Natural Philosopher Valued Senior Member

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    The God, I've had the impression that you've been defending Hawking radiation and black holes with event horizons. Was your defense simply based on the fact that it's the consensus view rather than something you agreed with personally?
     
  22. The God Valued Senior Member

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    No, I neither support BH nor HR.
    But unfortunately I am not agreeing with your reasoning against HR.
     
    Last edited: Mar 28, 2017
  23. RJBeery Natural Philosopher Valued Senior Member

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    Can you be more specific? I'd like to know where the disagreement lies. Perhaps you can tell me what you believe my reasoning is?
     

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