Singularity Vs Quantum Theory of Gravity

Discussion in 'Astronomy, Exobiology, & Cosmology' started by RajeshTrivedi, Feb 15, 2015.

  1. OnlyMe Valued Senior Member

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    Paddoboy, though it may not seem obvious when discussing the further collapse, the event horizon that emerges at the Schwartzschild radius crates the initial conceptual problem for both GR and Newtonian mechanics and the idea of black holes. While the singularity represents the location where predictions end, the event horizon is where the division between what we know and observe as reality and the black hole begins. Since a gravitational field is generally accepted as propagating at c, even the field becomes conceptually disconnected at the event horizon. This is one of the problems.., and perhaps the most important, that a quantum theory of gravitation should resolve.

    While establishing a surface associated with the collapsed mass of a black hole is important to avoiding the problems introduced by singularities, addressing the conceptual explanations currently associated with the predicted event horizon and speed of light escape velocities, is more important conceptually, where developing a successful quantum theory of gravitation is concerned.

    The speed of light escape velocity is a prediction that both conceptually establishes the event horizon and eventually leads to the singularity. However, an escape velocity of c is only significant if you assume there are any photons being emmitted and trying to cross that imaginary line in the sand, and connecting spacetime across the event horizon. If the physics of matter, inside the line in the sand we call an event horizon, were such that the emmission of all detectable EM radiation were suppressed, the escape velocity could be less than the speed of light and we still could not see anything inside the line in the sand. There would just be no EM radiation emmitted that we have the ability to detect. (Notice, I did not say, no EM radiation emmitted at all, just none we can detect.) This is where the true value of a quantum theory of gravitation, most likely lies. Not just in eliminating the singularity but in connecting the gravitational field that exists inside that line in the sand.., the event horizon, with the spacetime and gravitational field that describes the dynamic interaction of massive objects we can observe, outside of that line in the sand.

    While both Newtonian mechanics and GR have been and are very successful within their own limitations, neither one includes an entirely conclusive description of the fundamental mechanism(s), of what we know of, as gravitation.
     
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  3. paddoboy Valued Senior Member

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    Can't really disagree too much with what you have said, but again Schwarzchild's calculations show that mathematically once the Schwarzchild radius is reached, further collapse is compulsory and inevitable.
    https://books.google.com.au/books?id=rIyIlQwVCgkC&pg=PA55&lpg=PA55&dq=schwarzschild radius and gravitational collapse&source=bl&ots=uwYtTpEBvp&sig=Cf3MDOaSyGtXSCXQ8XdQio4wBM4&hl=en&sa=X&ei=8e_kVNv6NY_c8AXG-4HoDA&ved=0CBwQ6AEwADgK#v=onepage&q=schwarzschild radius and gravitational collapse&f=false
     
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  5. paddoboy Valued Senior Member

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    Worth noting for anyone interested, that the insignificance of density to be assigned to a BH, can be best realized in the fact that a SMBH would be many hundreds of times less dense than Earth's atmosphere.
    In essence the larger or more massive a BH is, the lower or more insignificant the density becomes, according to our current models.
    The Schwarzchild radius and EH diameter naturally increase in proportion to the BHs mass.
     
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  7. RajeshTrivedi Valued Senior Member

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    Thats it, this is not the GR prediction. Schwarzschild proposed that once the escape velocity for an object of mass M, is equal to c, even the light cannot escape....this is not the part of GR, this is derived independent of GR. For example c = Sqrt(2GM/r), and you get Schwarzschild radius as Rs = 2GM/c^2. So GR nowhere predicts the compulsory collapse, it is derived simply out of Newtonian Mechanics. And as on date the underlying principle is that once the object is smaller than Rs, there is nothing (no counter pressure to balance the Gravitational Pressure), and hence the object must collapse. So your statement that it is GR which predicts compulsory collapse is incorrect, you made this statement so many times and hence a correction was required.

    In general a BH is defined with Rs, kind of sphere of Rs. But almost the entire sphere (barring) the tiny singularity is empty, no material, it is not the uniform distribution of mass across the sphere of Rs. And hence density of a BH is d = 0 for the entire empty space, and as per theory the density of singularity (that tiny space at r = 0) d = infinite. So, you simply cannot apply d = Mass/Volume for a Black hole sphere of radius/Event Horizon Rs. The expected but meaningless result would be that density is inversely proportional to square of Mass...which will reduce as the mass of BH increases

    You seem to support the another vague assertion by a poster that speed of propagation of Gravity is c ? Fine GR indicates that because nothing moves faster than the c. But do you realize what is meaning of this speed of propagation of Gravity ? We do not know about Graviton, We have not yet detected Gravity Waves, GR also per say defines Gravity as warping of spacetime, there are theories which suggests Gravity filed as static field...then what is this speed of propagation of Gravity and why c ??

    You still have not answered the main question of OP. On what basis are you saying that QGT would resolve the singularity ?? I am saying it may not, rather it will not. For the simple reason that Quantum nature of Gravity will be at micro level (Quantum Particle level only....may be at that Planck's level), theory apart it is nobody's realistic take that such a huge mass of BH got reduced to such a tiny level ? I am sure there got to be some other mechanism. Just dwell some time on those variations of string theory and loop theory, do you see any chance that they or similar such theory can resolve singularity ? Nop.
     
  8. RajeshTrivedi Valued Senior Member

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    Gibberish, pure Gibberish....all the lines...not even a single sensible statement.
     
  9. OnlyMe Valued Senior Member

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    Which means, you don't understand. But then it seems there is a lot you don't understand.
     
  10. paddoboy Valued Senior Member

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    Still trying to get out of jail I see. The point in question is you failed along with many other things, to recognise compulsory collapse, now you are trying to dance around that fact.....
    Again for your perusal....
    http://en.wikipedia.org/wiki/Schwarzschild_radius
    The Schwarzschild radius (sometimes historically referred to as thegravitational radius) is the radius of a sphere such that, if all the mass of an object were to be compressed within that sphere, the escape velocity from the surface of the sphere would equal the speed of light. An example of an object where the mass is within its Schwarzschild radius is a black hole. Once astellar remnantcollapses below this radius, light cannot escape and the object is no longer directly visible.[1] It is a characteristic radius associated with every quantity of mass.TheSchwarzschild radius was named after the German astronomer Karl Schwarzschild who calculated this exact solution for the theory ofgeneral relativity in 1916.





    Despite your pretentious ranting and raving, this little side effect came up because you in another one of your misunderstandings about BH's tried to meaningfully assign density to it. You were informed by your's truly, Qu-russ, and two professors that it was not a meaningful exercise. Simple as that...no pretentious nonsense, just the predicted scenario that all a BH is, is critically curved spacetime, plus the mass at the Planck/Quantum level and as I detailed in my last post.

    As only me has noted, you are trolling, let me add that you are also lying.
    Your question has been answered.

    "The singularity in general relativity is not a "thing" so ascribing properties to it is not really a good thing to do - but when we have a better description of gravity, telling us what it is the singular nature of the GR equations are hiding, it will have an angular momentum associated with it".

    Cheers - G

    Prof Geraint F. Lewis,
    Professor of Physics & ARC Future Fellow,
    Sydney Institute for Astronomy,

    All your questions were answered in 3, 4, and 5.
     
  11. paddoboy Valued Senior Member

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    21,225

    And yet it is you who has started many threads deriding some scientific concept or other...some have been moved to the fringe, and the others are just a continued repeat of your error ridden pretentious nonsense.

    If you have any evidence for anything you have claimed in these threads, [including black holes do not exist] then submit the evidence, follow the scientific method and undergo proper peer review.
    Otherwise I can see the time coming when all your diatribe is shifted to the fringes where they really should be.
     
  12. paddoboy Valued Senior Member

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    A few questions for you Rajesh, to clear the air and reveal where you are coming from.
    [1] Do you accept the cosmology of BH's?
    [2] If not what do you suggest is the mechanism for the catastrophic effects we see on spacetime and metter/energy?
    [3] Do you accept the fact that once the Schwarzchild limit is reached, further collapse is compulsory?
    [4] If not, then how are you able to speak of a singularity, classical or otherwise?
    [5] Do you accept the fact that it is a meaningless exercise to assign density to a BH?
    [6] Do you realise that a BH can only have three properties? mass, charge and angular momentum?

     
  13. paddoboy Valued Senior Member

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    That appears to be the situation, and the game he is playing.
    same procedural methodology in every thread he has started...ask questions, get answers, deride the answers, claim he never got answers, telling a few porky pies, repeating himself continually, more lies, more questions, more answers, more ignorance of those answers.
    And he would like us all to believe he does not have an agenda?

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  14. paddoboy Valued Senior Member

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  15. RajeshTrivedi Valued Senior Member

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    Pl prove why this is not Gibberish ? What is escape velocity (SQRT (2GM/r)) has to do with emission of Photon ?

    Again please prove why this is not Gibberish ? You mean to say that we can see something only if it emits something ? Know anything about reflection ?

    This is purile...a step below gibberish. ..Who told you to mix up this emitted, detected, em, radiation, spacetime, event horizon etc with QGT ?? And what is this sand, taken from Sub Saharan Dunes ??


    You are not qualified to make this statement.


    Thats why I said, each and every line is gibberish like that Nuclear Force !! Prove otherwise.
     
  16. RajeshTrivedi Valued Senior Member

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    Thats what I had been telling since last two threads, but you kept on insisting that singularity must be spinning because no professor said that it is not spinning. why this change of heart ? Paddoboy.

    Moreover, on serious tone, please tell on what basis you are saying that QGT would resolve singularity...just the hunch or some basis ??
     
  17. paddoboy Valued Senior Member

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    If anyone has any doubt as to who and who is not qualified to make any statement about cosmology, please check out Rajesh's threads from recent times.....
    started by Rajesh.....
    http://www.sciforums.com/threads/black-hole-not-at-all.142714/
    http://www.sciforums.com/threads/so...nderstanding-of-main-stream-cosmology.142422/
    http://www.sciforums.com/threads/dark-energy-–-required-to-explain-a-plausible-mistake.142322/

    Take your time...there's some real juvenile claims and thoughts by our pretentious little friend in some of those threads.

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    Science progresses based on observational and experimental evidence.
    There is no proof!
     
  18. paddoboy Valued Senior Member

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    NO CHANGE OF HEART SWEETY.

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    NO PROFESSOR HAS EVER SAID THE SINGULARITY/MASS DOES NOT SPIN. IN FACT A FEW ADD THAT IT IS A REASONABLE LOGICAL CONCLUSION TO ASSIGN ANGULAR MOMENTUM.
    YOUR DISHONESTY CONTINUES UNABATTED.

    "The singularity in general relativity is not a "thing" so ascribing properties to it is not really a good thing to do - but when we have a better description of gravity, telling us what it is the singular nature of the GR equations are hiding, it will have an angular momentum associated with it".

    Cheers - G

    Prof Geraint F. Lewis,
    Professor of Physics & ARC Future Fellow,



    And another quick reminder about your continued lies and misleading claims, that will keep being repeated every time you utter one of your untruths.
    http://en.wikipedia.org/wiki/Schwarzschild_radius
    TheSchwarzschild radius was named after the Germanastronomer Karl Schwarzschild who calculated this exact solution for the theory ofgeneral relativity in 1916.


    Oh and you havn't answered the questions as yet......

    [1] Do you accept the cosmology of BH's?
    [2] If not what do you suggest is the mechanism for the catastrophic effects we see on spacetime and metter/energy?
    [3] Do you accept the fact that once the Schwarzchild limit is reached, further collapse is compulsory?
    [4] If not, then how are you able to speak of a singularity, classical or otherwise?
    [5] Do you accept the fact that it is a meaningless exercise to assign density to a BH?
    [6] Do you realise that a BH can only have three properties? mass, charge and angular momentum?
     
  19. RajeshTrivedi Valued Senior Member

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    None of my threads are shifted anywhere ? Why mislead the people ? I am just attempting to correct the nonsense spread by you guys, let me list down again....

    Following are patently incorrect statements..

    1. Singularity must be spinning.....
    2. Frame dragging has got nothing to do with Angular Momentum.
    3. singularity is at Planck's Level, but which level, not known to you.
    4. Entire Kerr Geometry is spinning, even inside of EH.
    5. GR predicts...repeat GR predicts...collapse inside Schwarzschild radius.
    6. Gravity overcomes nuclear force inside black hole.
    7. Singularity may get pulled by what ??

    And now my request, do not start copy paste again, people have received ample answers from either side so pl stick to the question in the OP only.

    and yes of course, as and when I get something peer reviewed, I will let you know.
     
  20. paddoboy Valued Senior Member

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    I'll leave your lies out of it at this time about who is claiming what.
    Your request for me not to start copying and pasting is denied..alrighty?
    Perhaps if you read them, you may learn something.
    But they'll certainly keep coming when required.

    Your acceptance of my suggestion of peer review, leaves two things quite obvious.
    [1] It is you and no one else that is promoting some agenda driven anti accepted cosmology.
    [2] The utter delusions of grandeur you are inflicted with, just like the other trolls such as chinglu, theorist constant. Best of luck with that!

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    nudge, nudge, wink, wink!

    I may start quoting some of your more crazy utterences from one of your past threads.

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    http://www.sciforums.com/threads/black-hole-not-at-all.142714/
    http://www.sciforums.com/threads/so...nderstanding-of-main-stream-cosmology.142422/
    http://www.sciforums.com/threads/dark-energy-–-required-to-explain-a-plausible-mistake.142322/
     
  21. RajeshTrivedi Valued Senior Member

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    [1] Do you accept the cosmology of BH's?

    Yes as mathematical representation, but I have my reservations about singularity, so in totality I do not believe in this BH as thought of today, worm hole, time travel, white hole concepts, there has to be something more sensible then all these..Mass just cannot vanish or leak into something else.

    [2] If not what do you suggest is the mechanism for the catastrophic effects we see on spacetime and metter/energy?

    That is possible if we have a mass/energy equivalent to M and causing gravitational effect...for that we need no singularity...moreover since you are the proponent of white hole and worm hole...tell me if worm hole exist then how can we have such impact on nearby spacetime..You can't.

    [3] Do you accept the fact that once the Schwarzchild limit is reached, further collapse is compulsory?

    Yes, because we do not know yet any other counter balancing pressure.. But my objection is that this is not GR prediction, this is plane simple Newtonian...You are drumming falsely that it is GR prediction.

    [4] If not, then how are you able to speak of a singularity, classical or otherwise?

    Who is speaking, you are saying it is spinning, it is at Plankc's level...all kind of non sense is coming from you. It is maths, Sonny, not Physics.

    [5] Do you accept the fact that it is a meaningless exercise to assign density to a BH?

    No, I am of the view that such a huge mass cannot reside at a point, so it has to have realistic density, and that will be resolved by ....?.....but not by QGT. I have explained in detail about density in this thread....But for you to really understand this density business you have to google some work on Neutron Star density first..


    [6] Do you realise that a BH can only have three properties? mass, charge and angular momentum?

    This is the BH definition aspect, Boy. But May I add energy also ? I can say that at any given time an active BH will have Energy (EM) + Mass + Angular Momentum......I have my reservation about charge.....Read the formation of Neutron Star...then you will also understand why I have doubt about charge.


    Paddo my agenda, is not to oppose mainstream, my agenda is to make it clear to those who are interested...I do not blah blah like that EFE EFE man without knowing what EFE is...without knowing what escape velocity is...



     
  22. paddoboy Valued Senior Member

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    Quantum gravity takes singularity out of black holes

    http://www.newscientist.com/article...gularity-out-of-black-holes.html#.VOWxleaUdZ8


    Black Holes and Quantum Gravity

    Black holes arise in general relativity, a classical theory of gravity. However, we need to include quantum effects to understand black holes properly.

    Roger Penrose and Stephen Hawking showed thirty years ago that, according to general relativity, any object that collapses to form a black hole will go on to collapse to a singularity inside the black hole. This means that there are strong gravitational effects on arbitrarily short distance scales inside a black hole. On short disctance scales, we certainly need to use a quantum theory to describe the collapsing matter. The presence of a singularity in the classical thoery also means that once we go sufficiently far into the black hole, we can no longer predict what will happen. It is hoped that this failure of the classical theory can be cured by quantising gravity as well.

    http://www.damtp.cam.ac.uk/research/gr/public/bh_hawk.html



    Quantum theory takes out singularity, suggests black holes are wormholes

    black holes are the single most interesting and puzzling objects in our Universe – that we know of. But as if they weren’t mysterious enough, researchers have found that if you apply a quantum theory of gravity to these bizarre objects, the all-crushing singularity at their core disappears, opening a whole new Universe of possibilities – literally.
    http://www.zmescience.com/science/physics/loop-quantum-gravity-big-bounce-theory-30052013/
     
  23. RajeshTrivedi Valued Senior Member

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    Prof Abhay Ashtekar is working on LQG for now almost a decade or so...still it is not concluded, the singularity remains as elusive as it was at that time...you have seen the response of various profs as early as last two threads....

    This is old paper, then why are you saying now...as and when QGT comes.....you should say that QGT (LQG) has already removed the singularity... can you ??
     

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