Black Hole.... Not so Black

Discussion in 'Astronomy, Exobiology, & Cosmology' started by RajeshTrivedi, Oct 1, 2014.

  1. paddoboy Valued Senior Member

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    Mostly agree, except again, I see the Singularity coming into vogue when GR starts to fail, and obviously that is at the Planck/Quantum scale.
    Coupling that with my previous mention, about a Singularity need not have Infinite quantities, but could lead to infinite quantities is important I suggest.

    OK...Planck scale is though a theoretically mathematically derived concept.



    The basis of this whole discussion is that Ravesh does not accept BH's and does not accept links or references to such. He has approximately said that in his own words.
    All I ever ask, is that anyone who doubts the existence of BH's, should then also be able to come up with another scenario that can describe the effects that are seen on spacetime and matter/energy within such regions.
     
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  3. OnlyMe Valued Senior Member

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    The way the above sounds, you describe the sigularity, associated with say a SMBH at the center of a galaxy, with an object less than the size of a proton. I am pretty sure that, at that point, you would already have reached gravitational forces that far exceed any known forces associated with QM. This is where using the term Planck scale and singularity together creates problems. QM can deal with Planck scales, but that does not mean that the total mass of a black hole can be put into a volume in the context that suggests, and be explained by either QM or GR.

    A model of quantum gravity may begin at the Planck scale, but it does not follow directly from that, that a black hole begins or ends there.
     
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  5. paddoboy Valued Senior Member

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    According to GR and the Schwarzchild limit and from what I know, that is the case.
    If the total mass does not end there, then we must accept the Newtonian/Michell version.
    GR remains our best effort in describing what we presume to be a BH.
     
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  7. paddoboy Valued Senior Member

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    http://backreaction.blogspot.com.au/2013/04/black-holes-and-planck-length.html
    Sabine Hossenfelder, aka Bee
    Assistant Professor for High Energy Physics at Nordita
    Living in Stockholm, Sweden


    extract:
    The Planck length appears in General Relativity as a coupling constant. It couples the curvature to the stress-energy tensor. Most naturally, one expects quantum gravitational effects to become strong, not at distances close by the Planck length, but at curvatures close to one over Planck length squared. (Or higher powers of the curvature close to the appropriately higher powers of the inverse Planck length respectively.) The curvature is an invariant. This statement is therefore observer-independent.

    in the normal Schwarzschild coordinates the curvature becomes Planckian if the radius is of Planck length. This also coincides with the mass of the black hole being about the Planck mass. (No coincidence: there is no other scale that could play a role here.)
     
  8. OnlyMe Valued Senior Member

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    GR remains our best description of gravity. When you start talking about the composition of a black hole, GR says nothing. The math ends with gravity becoming infinite which leads to a singularity.., but we know it cannot be infinite because infinite does not decrease with distance...

    Paddoboy, if you are discussing pure GR theory then go for the point singularity... But if you are talking reality, go find a physicist who believes that a singularity as you are describing exists, in reality.

    No one tell you for certain what is inside an event horizon. But neither can anyone tell you for certain whether the conditions inside an event horizon allow photon emmission either. If a black hole is not composed of matter as we know it, in one form or another, we cannot know that there is any light to get out or if there is light and it just can't get out! Everything we have is speculation and theory, as far as black holes and the insides of an event horizon is concerned.
     
  9. paddoboy Valued Senior Member

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    http://home.earthlink.net/~dolascetta/Black Holes.pdf

    A scientific paper
    extract:

    The theory of General Relativity says that the core is a
    singularity, a point of zero size and infinite mass density. However, General Relativity
    does not apply to Planck-scale physics. In the inflaton spacetime model, the maximum
    theoretical mass density, assuming that all fermionic points are stationary and in an
    excited state, is the Planck density. A singularity cannot form as long as the fermionic
    points are held apart by degeneracy pressure. Degeneracy pressure for points is much
    stronger than for particles. Since space is undergoing an accelerating expansion, it is
    possible that at some time in the far distant future space may become large enough for its
    gravity to overcome its degeneracy pressure just as it does for black holes, in which case
    it will collapse to a singularity. However, unless the entire universe collapses, no isolated
    singularity can ever form at any point. Therefore, we can conclude that there is no
    singularity in any black hole, and no information is lost.
     
  10. OnlyMe Valued Senior Member

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    You are quoting theory as if it had been proven. And putting it all in bold text, as if shouting makes it more real. No one cast test the assertions in that quote.., and notice that he is an Assistant Professor for High Energy Physics! Think that may play a role in how he interprets the world?
     
  11. OnlyMe Valued Senior Member

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    Again what you are doing is talking GR and quoting QM.
     
  12. paddoboy Valued Senior Member

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    21,462

    Agreed. I don't believe a point Singularity does exist.
    I do believe that GR fails to predict at the Quantum/Planck scale.
    I see this as the beginning of the Singularity.....which most probably does not lead to any infinities. I already said that.


    According to GR and the Schwarzchild limit, we do have a good theoretical handle of what happens, at least up to the quantum/Planck/singularity.
    And really, we have no complaints about GR as yet, other then its failure at the above mentioned level.
    But again, to doubt the existence of BH's, either GR or Newtonian Dark/Frozen star, one must or should be prepared to offer another theoretical concept to produce the effects that we observe.
     
  13. paddoboy Valued Senior Member

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    I'm not shouting, I'm highlighting.
    Assistant Professor? Sure. What part do you have a problem with?
     
  14. paddoboy Valued Senior Member

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    I'm using the existence of GR BH's as the default position.
    And until someone is able to model something that explains the observed critical effects we see with a better model, the "default position" is logically the one to fall back on.
     
  15. OnlyMe Valued Senior Member

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    If anything I have posted suggests to you that black holes don't exist, point out the post and I take a look.

    All I have been saying is that there is no evidence that supports and description of what form the mass associated with a black hole, exists as or what real volume it occupies. There are theories and speculations, but no testable hypotheses.
     
  16. paddoboy Valued Senior Member

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    I'm simply stating the reason for this thread.


    Agreed again, but GR is the best we have. And the Schwarzchild limit associated. And of course some theories and speculations are more logical then others.
     
  17. OnlyMe Valued Senior Member

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    The existence of a BH is not in question on this end. What form the involved mass is in, remains unknown. And though you do obviously default to the GR, you mix it up with QM. GR says there is gravity and describes the field. Once you discard the concept of a point singularity, it says nothing about the composition of any mass... And QM and QG have yet to provide any reasonably successful solutions.
     
  18. paddoboy Valued Senior Member

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    Most do default to the GR position.
    And all I'm saying is that GR says collapse past the Schwarzchild limit is compulsory.
    Then I'm saying GR becomes non applicable at the Planck/Quantum realm.
    Then I'm saying that is where the Singularity begins.
    Then I'm saying that the Singularity has in itself no infinite quantities, but may lead to Infinite quantities.
    Then I'm saying a future QGT may eliminate the Singularity or push it back further.
    These amongst his general no BH stance, is what the debate has been about with Rajesh.
     
  19. KilljoyKlown Whatever Valued Senior Member

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    I feel like you think all BH matter is in the same state for all BH's regardless of the size of the BH? I don't believe that myself. I think there is a big difference in the matter of a stellar BH and a SMBH of many millions of solar masses. What that difference is I can't really say, but I do know that more mass and corresponding gravity means a lot more pressure on the matter.
     
  20. dumbest man on earth Real Eyes Realize Real Lies Valued Senior Member

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    waffle
     
  21. dumbest man on earth Real Eyes Realize Real Lies Valued Senior Member

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    evade
     
  22. paddoboy Valued Senior Member

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    No, fact. A BH according to GR is just critically curved spacetime and a Singularity containing degenerative mass.
    Like I said, we discussed it earlier. You have the time...do some checking.

    Please Register or Log in to view the hidden image!

     
  23. paddoboy Valued Senior Member

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    References to the contrary?
    Cat got your tongue?
     

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