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Hawking radiation weirdness

  1. Sep 17, 2014 #1
    The way I understand Hawking radiation is that black holes decay by sucking in anti particles from the virtual particle pairs that are created right at its event horizon. I also understand that these anti particles reduce the mass of the black hole instantly when crossing the event horizon? And that these things are so in Hawkings theory because it is the consequence of the laws of entropy and the information conservation law. Is this correctly understood?
     
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  3. Sep 17, 2014 #2

    mfb

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    Particles and antiparticles alike.

    There is no "instantly", especially for black holes where time passes at completely different rates for different points. If you compare the mass before and afterwards, you'll see it decreased.

    Entropy, yes. It is unclear if Hawking radiation is relevant for information conservation (and if information is conserved at all).
     
  4. Sep 17, 2014 #3
    Are the particle and antiparticle produced from vacuum energy inside the event horizon? If so, I'm not sure it's correct to say that these events happen "right at the event horizon". Would it be more correct to say that the event begins just inside the event horizon, even though the two resulting particles end up on opposite sides?

    John, do you believe that the black hole eventually vanishes because antimatter is sucked in which annihilates the matter inside the event horizon of the black hole?
     
  5. Sep 18, 2014 #4

    mfb

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    They are not inside, otherwise they could not get out. "Just outside" is a better description.
     
  6. Sep 18, 2014 #5
    I thought that HR depends on quantum tunneling. From Wikipedia's article on HR: "In another model, the process is a quantum tunnelling effect, whereby particle-antiparticle pairs will form from the vacuum, and one will tunnel outside the event horizon."
     
  7. Sep 18, 2014 #6

    stevendaryl

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    There's an intuitive way of describing Hawking radiation, which is in terms of the black hole sucking in virtual particles. Then there is a more technical explanation in terms of describing particle creation/annihilation from the point of view of an accelerated reference frame. I'm not 100% certain that the intuitive explanation has been shown to be equivalent (in some sense) to the technical explanation.
     
  8. Sep 18, 2014 #7

    mfb

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    If you look close enough, every simplified model will have its limits. Based on the first post, I guess we should not go into too much detail here.
     
  9. Sep 18, 2014 #8

    phinds

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    No, they form outside the EH. Even tunneling won't allow you to escape from inside the EH. It's the ultimate roach motel.
     
  10. Sep 18, 2014 #9
    So articles like this one are just plain wrong? In the article, Andew Hamilton (an astrophysicist at the University of Colorado) describes how a particle spawned inside the EH can escape via tunneling.
     
  11. Sep 18, 2014 #10

    mfb

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    As elementary particles of the same type are indistinguishable, how do you tell if a particle escaping is the same as another particle that was somewhere else before?

    This part is just wrong.
     
  12. Sep 18, 2014 #11

    phinds

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    Well, I'm not an expert by any means but from all I have read, yes, he's wrong. I notice that he says "particles are also waves" which is probably just 'cause he's writing for a lay audience, but I think a QM guy is really more likely to point out that a "particle" is not a particle OR a wave, as those terms are understood, but rather is a quantum object that will act like a particle if you measure for particle properties and act like a wave if you measure for wave properties. This is NOT simple semantics and if he in fact doesn't understand it (and again, I think he probably does understand it but is dumbing down his discourse) then nothing else he says is very trustworthy. Also, as mfb pointed out, the concept of a quantum object getting sphagettified doesn't make sense.

    Also, and unfortunately I can't give you a citation but I learned about it here on this forum, Hawking himself has said that this whole business of "virtual particle pairs" is bogus and was simply a "dumbing down" that HE did because it was the only way he could think of to state in English what his math actually says about what is now called Hawking Radiation.
     
  13. Sep 20, 2014 #12
    The quote is from his original paper on Hawking radiation, in the introduction:

    From here is you can get by the paywall: http://link.springer.com/article/10.1007/BF02345020
     
  14. Sep 20, 2014 #13

    phinds

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    Thank you.
     
  15. Sep 23, 2014 #14

    Imager

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    If a black hole absorbs either an anti or normal particle, why is not still a net gain of mass?
     
  16. Sep 23, 2014 #15

    phinds

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    Dark matter is not made of anti-<anything>. I think maybe you ought to read up on just what dark matter IS.
     
  17. Sep 23, 2014 #16

    mfb

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    The "particle" it absorbs is not a regular particlem it is virtual - if you want to assign an energy value to it, it will be negative (including the rest energy of the particle!).
     
  18. Sep 23, 2014 #17

    Imager

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    Hi Phinds, I don't mean to imply Hawking radiation is related to dark matter. If they are related, then I admit to being more confused than usual. :)
     
  19. Sep 23, 2014 #18

    phinds

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    Nuts. I think I got confused about what thread I was in. Sorry. :oops:
     
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