Hawking radiation

Discussion in 'Physics & Math' started by hardalee, Sep 16, 2015.

  1. origin Heading towards oblivion Valued Senior Member

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    It always surprises me when you make statements like this. What do you mean by 'known to be real' and what do you mean by theory? General relativity is a theory, is it not known to be real in your opinion? Is the Standard Model known to be real or 'just' a theory. I do not understand how you can make statements like this since I was under the impression that you had a degree in physics.

    The Casimir effect certainly seems real enough to me! Casimir predicted the effect from virtual particles in 1948 and experimentation in the 1970's showed the effect was real. So what's the problem?
     
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  3. paddoboy Valued Senior Member

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    I agree that you are an arrogant manipulating person who lacks any intestinal fortitude to answer relevant questions that show you are wrong.
    In answer to your "quote mined question", my position is clear and aligns with the general consensus of all the professional replies.

    Your position is totally wrong as it has been over many cosmological and BH threads since you began to infest this forum in either of your guises.

    Worth noting that while you cunningly lie and misinterpret any person that happens to agree with me as somehow being in cahoots with me, I do not do need to do the same for you.
    I have not found anyone [including the couple of adversaries that I do have] that dare attempt to agree or align with yourself.
    In fact even these couple seem to stay well clear of your craziness and emotional error ridden outbursts.
    That about says it all.
     
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  5. paddoboy Valued Senior Member

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    This seems to tell me rightly or wrongly, that you want to appear to be taking an even handed approach, with a view to both sides. Quite admirable I agree, but isn't it also true that scientific theories do grow in certainty over time?

    the god's criticism do not concern me, as most of them have been shown as either petty, vindictive and pedantic, or just plain wrong. Remember the Kerr metric BH discussions?
    But I'm certainly interested in what you say about me and my use of the "quote" function. On that score I certainly will try and alleviate any confusion about what my opinion is and what I'm quoting from any reputable expert.
    It would help if you could give me an example of where you have had a problem in differentiating between the two.


    Once again, your attitude appears to be one that is walking a picket fence, as opposed to my opinion and the degree of certainty I invoke.
    Even before tashja's excellent professional replies, in my opinion, the true nature of HR was laid out and explained in at least two links by myself, and one by bruce.
     
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  7. paddoboy Valued Senior Member

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    But there is! HR is generally mainstream accepted based on the issues, analogues and experiments we have already discussed.
    Particle pair creation is an integral part of quantum theory. HR is an extension of that.
    We are unable to directly observe BH's, but at the same time we are unable to attribute logically the effects on matter/energy and spacetime that we observe to anything else. [Ignoring our fanciful Black Neutron Star that rajesh was proposing and that was totally demolished]
    We have no direct evidence that stellar mechanism is via nuclear fusion, but again we cannot explain it any other way.
    In essence and as I often say, scientific theories do grow in stature and certainty over time.

    The very nature of some aspects of the beast probably means that there are aspects we may never be able to observe directly. A future validated QGT included.
     
  8. paddoboy Valued Senior Member

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    It is really about time that you realise that not too many are taking notice of your obvious agenda driven dishonest take on anything that smells of mainstream acceptance.
    Perhaps this is due to your BNS being demolished and fading into oblivion and lost in cyber space.

    My stance mostly aligns with Professor Unruh and Professor Carlip, which you, being you seem to have totally ignored.

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    *hint* Ignoring posts and expert advice that is down in print in threads do not make them go magically away or disappear!

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    Professor. Unruh and Professor Polchinski gave great replies as did Professor Helfer, although the latter with less conviction than the other two, [three including Carlip] shall we say.
    Irrespective though of his less conviction, he certainly makes it obvious that he also agrees with the other three re HR and its theoretical application to BH's ....something else that you seem to have overlooked in your fanatical desire to regain some lost credibility....Not that you have ever had much of that, with past threads being shifted to the fringes.

    Again, just to alleviate your usual utter confusion, and your usual lack of understanding of the English language, imho, HR is no where near as certain as SR/GR but it is indirectly supported by extensions of particle pair creation and quantum theory, and seems to be a logical extension of that.
    That opinion of mine seems to align with our expert links I have obtained, and the professional replies by tashja.
     
    Last edited: Oct 9, 2015
  9. OnlyMe Valued Senior Member

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    What do I mean by know to be real and what remains theory...

    Things we can observe and/or confirm experimentally are real. The theories we use to describe what we observe and predict what might be, are just that theories.

    But this thread is about Hawking radiation and initially as it involves black holes. The theoretical solutions that give us black holes, ultimately also predict mathematical singularities... Which not many credible sources believe exist in reality... And what evidence we have that supports any of the predictions about gravity that leads up to a black hole, does not include evidence that any event horizon exists. So while I believe, we can be fairly safe in asserting that something that at least superficially acts like a black hole - exists, we can't see it, but we can tract the orbits of stars that obit it.., what form it takes in reality remains theoretical. And any speculation about how that unobserved thing, interacts with anything other than the stars we can observe orbiting it remains at best theoretical and tends toward speculation. Most of the time speculation based on a theory that says the black hole is a mathematical singularity..., that I don't believe exists.

    The standard model is a theory, that again does a very good job of describing what we can observe of the fundamental nature of matter.

    Most of these discussions don't stick with what does GR, or SR of even QM say about the things we can observe directly. They stray into the grey areas of hypotheticals and the what ifs associated with things like, how a black hole event horizon we cannot confirm is real, that surrounds a black hole that our best theory of gravity, tells us is a mathematical singularity, might interact with the virtual particles of a quantum vacuum, that we cannot detect... And it is all done with a certainty that they are real, even where none of these things have been demonstrated to be real. They are mostly all things predicted by otherwise successful theories.

    Now are any of those things real? I don't know! Some I believe are likely to prove to be, but until they have been proven.., they remain theoretical.

    And no I don't have a degree in physics. I studied physics and mathematics formally in the late 60's, but I was being pushed toward QM and what later became string theory.., and I just wasn't interested... I got bored easily back then, so I quit and took over a family business. In retrospect I wish I had spent more time looking into QM back when it would have been easy.

    The Casimir effect does not require the virtual particles of the quantum vacuum to be explained. The EM spectrum of the vacuum is sufficient. Even then it's a theoretical explanation not a proof. I believe the dynamical Casimir effect is closer to proof, but there remains some doubt even there.

    Theories and models describe things around us, things we can observe and figuratively reach out and touch.., and they often are use to make predictions about things far beyond what we can test and prove. The theories and models always remain theories and models, the things they describe that we can reach out and touch (again figuratively) are real, and those prediction that reach into the past, the future and the dark distances of space that we cannot yet explore remain theoretical projections, and sometimes out and out speculation.

    I don't know if it means anything to anyone, but it is my belief that our imagination is one of.., if not our greatest asset, which makes speculating about what might be, a powerful tool in the quest to understand what lies just outside our reach.

    There are a couple of posts from other threads. One by rpenner and the other James R that I think everyone should think about and keep in mind when in discussions like this, mostly because these are lay discussions and how we phrase things gets taken sometimes literally...

     
  10. OnlyMe Valued Senior Member

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    Theories are theories. They are useful to the extent that they accurately describe reality. I think your use of the word certainty in this context is misplaced. They do tend to become entrenched over time, but that may be a problem rather than an attribute.

    Look again at the rpenner & James R quotes in my earlier post.

    Sometimes by not using the quote function for a quote from an outside source it is not always obvious that your comment and the quote are separate. That may be in part that I use a portable device...

    I really liked the way Professor Helfer commented on the subject, posted by tashja in the post linked below. It drew attention to my own use of a more physical reference to virtual particle/anti-particles, where as he indicated they are not really particles in that sense. Something I knew and yet... And something that is not as clear in the response of Professor Unruh, or his papers. Though in reading the published papers it should be understood. Different peer group and certainly not generally intended for a lay audience, where misinterpretations and understanding

    Note the first sentence, second paragraph of his comments, which supports my suggestion that even the existence in reality of Hawking radiation is not a matter of mainstream consensus... Hawking radiation, as it involves black holes, is speculation about how untested predictions of two theories overlap.

     
  11. OnlyMe Valued Senior Member

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    See the Prof. Helfer comment again.

    A component of the descriptive/predictive model....

    Not just....!

    What is logical is sometimes dependent on the assumptions you begin with. There is nothing logical about a black hole being a mathematical singularity in reality, but that is where several solutions to GR wind up... Note I laid the weight on the solutions not GR itself, because to reach the singularity they have to include assumptions about gravity that are not required to explain gravitation in the weak field.., meaning everywhere that does not include a singularity.

    But we do understand how fusion can be produced and with only a few reasonable assumptions that those conditions do exist inside a star.

    Yes they grow in stature or perhaps as I said earlier they become more entrenched, but as soon as a theory gains the status of certainty, it would no longer be theory. It would be an exact description. We aren't there yet.

    I am not as skeptical about there being a quantum theory of gravity, in the cards. We probably just need to get shed of how certain we are of what we think we already know, before we will arrive there.
     
  12. brucep Valued Senior Member

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    These folks are showing us that there's multiple ways to model the physics. These remind me of the interpretations of QM. Thanks for the great comments and tashja.
     
  13. paddoboy Valued Senior Member

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    I have never used the word "certainty" in isolation......more certain in a comparable mode, or near certain are phrases I use quite intentionally.
    I have no problem with either or what either have said.
    I have said the same thing myself.

    OK, I see what you mean. Will rectify.

    I actually preferred my own earlier Professor Carlip link, but all are essentially saying the same thing with different emphasises on certain aspects.

    If we get down to the nitty gritty, any "certainty" on my part, [and as I have pointed out, I don't believe there has been] has been initiated by the stupid certain claims of other parties which I believe you have recognised.


    I would need more than one sentence from one Professor to convince me that HR is not generally the consensus in mainstream physics.
     
  14. brucep Valued Senior Member

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    4,098
    The whole thing. The black hole thermodynamics and Hawkings derivation for black holes radiating in a black body spectrum are very important theoretical predictions leading to quantum gravity research.
     
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  15. The God Valued Senior Member

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    3,546

    Nope, see my post # 45, part of which is reproduced below...

     
  16. paddoboy Valued Senior Member

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    As usual, you seem askew to what others are talking about.

    Professor Unruh said.....
    The problem is that the notion of particles is not an invariant notion but depends on the state of motion of the observer. Exactly the same state that one person will say has no particles in it, the other will say there are lots of particles in it, as measured by a particle detector. Particles in a quantum field theory, are an epiphenomenon, not something fundamental to the theory.



    William G. Unruh | Canadian Institute for|
    Physics&Astronomy


    Even Q-reeus said in post 136 with regards to Professor Heifer's remarks............
    "His response does imo acknowledge there are consistency issues, although it's also fair to say he believes that HR is more likely real than not".
     
  17. The God Valued Senior Member

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    'certainty' was being put by whom ?
     
  18. The God Valued Senior Member

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    OnlyMe;

    A discussion involving 3-4 professors, on particle physics, vacuum energy, Hawking radiation, Thermodynamics, Black Body............you relate this with lay discussion?
     
  19. paddoboy Valued Senior Member

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    This forum does not have any more gods such as yourself.

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    Although so far your input has left much to be desired and seems to have gone unnoticed.

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  20. sweetpea Valued Senior Member

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    1,329
    Onlyme, You seem to make this mistake yourself...
    You may remember on another thread we 'talked' about GR being a model/tool.
    You really showed there you don't understand the geometrical space-time manifold idea and maximum ageing to give the worldline of a rock on such a manifold. You did that by using the word " freefall', and you think there is a force required to change momentum.

    As I stated on that thread back then...For the purposes of using the geometrical manifold model you just take it that space-time is altered by mass and energy. The same for the force idea, you take it there is a force at work. Why does mass and energy alter space-time or what is the mechanism of how the force works at a distance.. don't need to know to make predictions because we are only using models built on observations.

    My bold below shows your strong urge for a force.
    You show here you think there is a need to include a 'force' in to the geometrical space-time manifold model
    You seem to have an urge to put one model 'force idea' into the geometrical space-time manifold idea/model.

    You seem to forget these are models we are talking about. Freefall is used in the force model/idea.
    Here's rpenner on force...
    http://www.sciforums.com/threads/ne...he-speed-of-light.136920/page-11#post-3147077

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    Last edited by a moderator: Oct 10, 2015
  21. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    hawkings has succumb to obsolete.
    nothing more nowadays.
     
  22. JohnFibonacci Registered Member

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    "When the debate is lost, slander becomes the tool of the loser." -Plato
     
  23. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    except the loser is an obvious, non scientist as they spew.
    LIM...

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    shrugs. get it ?
    then goes around using buzz words or quotes that are out of context.
     

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