Black Holes and Information Loss

Discussion in 'Physics & Math' started by RJBeery, Mar 21, 2017.

  1. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    • Threads merged. Please do not post such naked links.
    This should be a fun one! As always, all mature feedback is welcome...

    Black Holes and Information Loss: https://goo.gl/tzna8P
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    <this is cross posted from the Astronomy subforum, wasn't sure which one is more appropriate>

    This should be a fun one! As always, all mature feedback is welcome...

    Black Holes and Information Loss:https://goo.gl/tzna8P
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. DaveC426913 Valued Senior Member

    Messages:
    6,645
    It is bad form to post context-free links without any follow up.

    If you have something you wish to say, you should say it here. You can refer to the article to support your point, but this is really just link-spamming.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. karenmansker HSIRI Banned

    Messages:
    638
    Geez Dave! . . . . the (linked) article is HIS!!! (RJBeery's)
     
  8. rpenner Fully Wired Staff Member

    Messages:
    4,833
  9. Schmelzer Valued Senior Member

    Messages:
    3,603
    Oh, I see even Baez makes (or copies from Anderson) errors in an attempt to give a simple description:
    Wrong. A non-unitary evolution, like in a theory with a wave function collapse, can be completely fine with preservation of probabilities. It is only in conflict with the Schrödinger equation, which is unitary.

    Here I would simply like to disagree with him. There are not much parameters to describe a black hole if one does not describe it in terms of some more fundamental theory, essentially nothing except its mass, and if you don't have more than a single parameter, don't wonder that you get the same spectrum as black body radiation.
     
  10. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    I was hoping for more substantive criticism. I also hope the irony is not lost on you that you post two naked links as a reply after chiding me in a PM for posting a link as the OP.

    Please Register or Log in to view the hidden image!



    This is Baez' polite way of saying we don't really know, of course, but I try to make the logical argument that Hawking radiation as a result of the presence of an event horizon is logically flawed. If anyone would like to address any fallacies in my reasoning I would really appreciate the engagement.
     
  11. The God Valued Senior Member

    Messages:
    3,546


    It is not clear how you arrived at your conclusion. Is it that EH and BH exist but no information loss? If so then your ping pong balls do not conclude that.

    If you are saying that BH and thus EH do not exist, then again your argument is not sufficient. I feel a better clarity is required.
     
  12. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    The third page makes the clearest argument:

    If Hawking radiation requires an event horizon but allows for radiation to occur in our past light cones then it is not compatible with general relativity's definition of event horizons not existing in the causal past of the infinite future.
     
  13. The God Valued Senior Member

    Messages:
    3,546
    First and foremost I do not think even Hawking understands what his name sake radiation is.

    Secondly in the context HR is used by him to resolve the paradox. You cannot take a stand that this resolution is bad, so paradox does not exist. What kind of argument is this?
     
  14. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    My stance is that this resolution is a logical contradiction. Read page three of the paper.
     
  15. The God Valued Senior Member

    Messages:
    3,546
    Yes, so what? Not many are positive about HR.

    Accepting that HR based resolution is a contradiction, does not conclude that paradox itself is bad.
     
  16. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    Well an acknowledged logical contradiction should mean that everyone is positive that HR, as described, is not occurring. The contradiction applies to both HR and information loss; if information has indeed been lost to an event horizon from the perspective of all frames external to a black hole then that "loss" exists in past light cones -- this is a direct contradiction of an event horizon "not existing in the casual past of future null infinity."
     
  17. Schmelzer Valued Senior Member

    Messages:
    3,603
    Claims about "logical contradictions" of mainstream science are usually a very strong indication of crackpottery.

    But in the case of HR one has to make an exception. The point is that the theory used there - semiclassical gravity - makes sense only as an approximation and is, essentially, known to be inconsistent. And inconsistent means, in principle, a possibility for logical contradictions too. Add the trans-Planckian problem, which is that semiclassical theory is applied in a domain where assuming its validity does not make sense, and you have a case were it can possibly be justified to name something a "logical contradiction".
     
  18. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    Agreed. Nevertheless, I'm using an excerpt from the LHC Safety Assessment Group:
    Do you personally believe that micro black holes do or have existed, Schmelzer? This statement suggests that there is a general consensus in the affirmative. I'm looking for a resolution for the idea that black holes "have existed" in our past light cones that does not directly contradict the theory of general relativity.
     
  19. Schmelzer Valued Senior Member

    Messages:
    3,603
    I see no reason to believe in the existence of micro black holes, nor does the mainstream believe they exist. Some people think about elementary particles being such micro black holes - which is a quite natural idea if one thinks about them in terms of point particles (a natural replacement for a point particle in GR would be a micro BH), in this case they would have to be stable. If there is HR, they would radiate heavily and explode in short time.

    The talk about evaporating BHs is, roughly, only sloppy talk. What would be a BH in classical GR would have to radiate if HR exists, and, therefore, loose mass, and finally disappear. To name a disappearing horizon a horizon makes no sense, so to name a disappearing BH a BH makes no sense too, but this is simply the cheap way to name - use the old name, which makes sense in classical GR, for the thing which behaves quite differently in semiclassical theory, even if it does not really make sense.

    Of course, this fear about the LHC producing black holes which become dangerous for mankind is laughable nonsense, a typical case of the harm that can be done by bad science journalism. http://www.express.co.uk/news/weird...N-admits-experiments-could-create-black-holes

    In the mainstream, many people believe in HR. This has a quite simple reason: They have not checked the details, but simply trusted. As a scientist, you have no choice but to trust most of the results claimed by the mainstream, simply because you have not enough time to check them all. What you can do is quite restricted - to learn the basic theories, and to learn the basic experiments supporting them, and to see that to find another theory which would fit the same experiments is a very hard job. So, you can see that the leading theories are a good guess. More is impossible anyway - independent how much observational support there is, it cannot prove the theories are true, but only that they are, at the current moment, good guesses. So, if you, after this, simply believe the claims of experimenters that the observation fits what is predicted by the theories, there is, first, a good chance that this is indeed true, second, even if not, the harm is not that big. Because if there is some contradiction with observation, and it is not seen some time, so what? With time, accuracy becomes greater, and after some progress the failure will be easy to observe.

    The situation in fundamental physics is different, there are no experiments to guide it beyond the SM, and most of the theories are wild and unjustified speculation. So the probability is high that anyway they are completely wrong. So, in this sense there is also no big risk.
     
  20. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    That isn't the impression I have and it certainly isn't the impression given by the authors of the LHC Safety Assessment paper. If the energy of a cosmic ray is theoretically sufficient for a micro black hole what do you believe happens? Also, what do you think the mainstream believes would happen?
    Forget micro black holes for a moment. Do you believe there's a black hole at the center of our galaxy containing an event horizon? And do you believe this black hole is emitting Hawking radiation? It sounds like you believe in black holes but consider them to be truly eternal.
     
  21. Schmelzer Valued Senior Member

    Messages:
    3,603
    The problem is not the energy. For every energy, there is a corresponding Schwarzschild radius, and if that energy becomes localized in a region that small you get a BH. But how to concentrate an energy in such a small region is simply open to speculation.
    First, I have my own theory of gravity, and in this theory there are no BHs, but stable stars which look almost like a GR BH would look like. Because outside a very tiny environment of the BH horizon size the solution is almost exactly the same as in GR. In this sense, I don't believe in a BH at the center of the galaxy. But that piece in the center would, if GR would be true, a GR black hole. I do not believe in HR, the derivation of it is faulty because of the trans-Planckian problem. During the collapse toward a BH, there is some Hawking-like radiation.
     
  22. RJBeery Natural Philosopher Valued Senior Member

    Messages:
    4,136
    That's fascinating because I believe the same thing, except it isn't my own theory of gravity. I believe that GR itself does not predict black holes with event horizons, and that the removal of the mathematical singularity via coordinate changing has led the community astray.
     
  23. Schmelzer Valued Senior Member

    Messages:
    3,603
    From point of view of GR coordinates do not matter. And the mathematics of the BH solutions is fine. So, the problem with GR is a different one. That they have to live with closed causal loops seems much more serious for me.
     

Share This Page