Neutron Star to Black Hole

Discussion in 'Astronomy, Exobiology, & Cosmology' started by RajeshTrivedi, Jan 12, 2015.

  1. paddoboy Valued Senior Member

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    21,225
    Not convenient at all, but logic and common sense, which you seem to have let fly out the window.
    Maybe at this time you need to drop your pretense about knowing anything about BH's, for reasons not the least being, you doubt their existence, yet are unable to suggest any other entity or scenario that could have the same effects on spacetime, matter/energy that we observe.
    Despite your continued ducking and weaving of the many questions put to you, and the pretentious nonsense you babble on about, you are yet unable to explain how we have observational evidence of frame dragging/ergosphere, without a spinning mass.....

    Again, let me inform you that no professor, no link [most which you ignore, then again ignore my comments on you ignoring them] have ever said Kerr ring Singularities do not spin.
    Perhaps the question that should be put to the professors, is "Is it correct to say kerr singularities do not spin"
    Because in essence, among your myriad of other errors and misrepresentations about BHs. that is what you are claiming.
    And while no professor and no link has ever said kerr singularities do not spin, most suggest that it is a reasonable assumption, [which like other pertiment comments you ignore] to make.
    again the following:
    "I think that to say that "the Kerr's ring singularity is spinning" is a fairly reasonable intuitive interpretation of the Kerr geometry.
    Kerr geometry has angular momentum, and it is reasonable (at least in some respects) to think of the ring singularity as the source of this angular momentum; and for this reason it is reasonable to interpret the situation as if the ring singularity is rotating.
    Best regards,
    Amos Ori

    http://www-conf.slac.stanford.edu/einstein/talks/kip-bhs.pdf


    "I don't know what it means to say that the "singularity spins" or not. The Kerr solution certainly has angular momentum---a notion that is well defined at infinity---and it would probably not be unreasonable to view the ring singularity as "producing" this angular momentum".
    Robert Wald:


    No Professor has ever said "A SINGULARITY DOES NOT SPIN"





    And I suggest to you, that if all the professors were to be "privileged" to all your comments re BHs here and the other BH thread, your silly sanctimonious pretentious attitude as shown above, they would be aghast with disbelief.

    Let me again inform you, no forum member has supported your concept, and no professor or link has ever suggested that the Kerr Singularity does not spin.
    Those are facts.
     
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  3. paddoboy Valued Senior Member

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    And here's the man himself and an illustrative paper on the Kerr metric.
    http://www.astro.sunysb.edu/rosalba/astro2030/KerrBH.pdf
    And note on page 3 where he says.....
    Because spacetime is “stuck” to the horizon, space is dragged along with the spin. This appears as a tornadolike swirl in hyperspace"
    which happens to be an extract from Thorne's book , "Black Holes and Time Warps" of which I have a copy.
     
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  5. tashja Registered Senior Member

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    Fortunately for us, we have some expert mathematicians on this site that can clarify this issue of dividing by zero, and whether we can say 1/o = infinity. Here's one of our experts reply:

     
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  7. OnlyMe Valued Senior Member

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    While I understand rpenner's conclusions, I don't think they apply in the context being debated here.., mostly because the context is not restricted to the math. Even Kaku's statement can't really be said to be 1/0, (I believe that was a simplification intended for a lay audience), because the math breaks down either at that point or even as it approaches that point... Which leads to the singularity everyone agrees is not a part of our physical reality. A step back here because I don't really know what Rajesh believes or what his motives are.

    But it may also be that I just don't see how the special operations on special numbers, rpenner mentions applies here. I am reluctant to assume that he is suggesting anything more than a mathematical context. This discussion has been all over the place. If you stay completely within the context of the math and entirely divorced from physical reality, perhaps an argument could be made.., but that has not been the case here has it. The discussion has been commingling abstract mathematical theory (the end point characterized as mathematical science fiction by one of your sources), physical reality (which though it must include a massive object does not involve a singularity, in the mathematical context) and assumptions about what we cannot observe based on intuition and some small measure of logic. And the debate bounces back and forth between...

    If in the equation, 0 = 0 (zero = zero as in nothing), then 1/0 is not infinite. It is at best undetermined.
     
    Last edited: Feb 13, 2015
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  8. paddoboy Valued Senior Member

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    I believe from his overall claims in this and the other BH thread, that his motives are reasonably obvious.
    [1] He does not believe BHs exist.
    [2] He doubts the conclusions and facts that once the Schwarzchild limit is reached, further collapse is compulsory.
    [3] He claims the density of a BH as a meaningful concept.
    [4] He claims frame dragging can/does exist with any rotational mass.
    [5] He argues strictly from the classical point singularity context, and refuses to recognise our models breaking down at the Planck/Quantum level and the beginning of the singularity, despite confirmation from at least one professor.

    And he stubbornly refuses to address any of those 5 issues and my claims thus.

    The half a dozen or so professors I believe support my concept of a Kerr BH, and the many links I have given certainly do.
    The professor's answers though, from the ones he cherry picks, and the ones I also cherry pick, to support each of our claims, are just placing emphasis on two aspects of a BH.
    [1]What can be inferred and cannot be inferred by our models.
    [2]And what can be logically and reasonably inferred despite our models not covering those aspects.
    I support [2] and I believe all the professors and links also support [2] evidenced by the fact that Rajesh likes to deride, that no one yet has ever said a Kerr BH does not spin.


    The logic and common sense principals in [2] are....
    [1] Frame dragging [the ergosphere is caused by a rotationg mass]
    [2] Spacetime is not a discontinuous entity, and what we see in the ergosphere logically is connected to the spacetime within the BH, and the critical curvature of that spacetime, made by the mass.
    [3] There are no physical aspects of a BH except one....the collapsed mass that governs all other parameters of that BH including the EH and the spacetime curvature.

    And yet Rajesh has continually failed to address any of those, and openly admits ignoring all links.
    Am I wrong for speculating an agenda of sorts?
     
    Last edited: Feb 13, 2015
  9. RajeshTrivedi Valued Senior Member

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    1,366
    OnlyMe,

    It is sad that you talk of EFE, singularity, infinities, GR maths etc and you do not appreciate the basic aspect how the singularities appear. You are just wriggling out with the help of English-language, but people have seen how shallow your knowledge is, it was clear to me long back when you referred to Nuclear Force with respect to collapse of star, but now this 1/0 has brought you to...well.....deep well..

    Pl see the below step by step equation... (forget the reality, just the steps)..


    density proportional = 1/r^3

    So we see what happens to density as r ---->0 whether it becomes uncertain like you are howling or goes to infinity...

    Start with a Neutron star of around mass 3M and radius 10 Kms....forget the spin to understand the simple singularity first
    For this mass, the Schwarzchilds radius will also be of the same order or so..

    1. Density of this star = 3M/V = 3M/1.33*pi*r^3 = 10^18 Kg/m3 (Only the significant zeroes)

    (this density is fairly high, almost close to atomic nuclear density).

    2. Now suppose due to accretion this core gets inside Rs (neglect the increase in mass), so obviously it will collapse dynamically (Paddo ??), that means its r would start decreasing from 10 Kms to ?? let us say it becomes 1 Km...

    So New density when the core size becomes 1 Km = 10^21 Kg/m3

    (this is huge, because it is more than even the nucleus density, but hold on...)

    3. The collapse has to continue because there is no known counter balance theory as on date...so within a fraction of second this r may become say now 1 Micron = 10^-6 meter

    The new Density = 10^39 Kg /m3.. !!!

    a very determined value, not uncertain so far, very large value, why because r --->0, pure maths.

    4. Now the collapse is continued and in the journey towards r --->0, this core will encounter the Paddoboy Science (Planck's Level Lp), so at

    r = Lp = 10^-35 meter,

    The density = 10^136 Kg/m3.

    Can you appreciate this number ? Paddoboy gave up the maths when I asked him, because he has been talking about Planck's level without knowing which parameter.

    5. anyway...the singularity is at r= 0 only, and theoretically Lp is still higher by any imaginable factor from r = 0, so please keep reducing the r, you can put r = 10^-10000000 meter and see for yourself what you get..infinity or Uncertainty ??.........(Recall that one of the prof very categorically stated that classic singularity is at much lower level than Planck's level...this is what he was referring to).

    just by the way Kerr Singularity has slight different maths but can you still assign any meaningful physical property to such singularity like Spin etc ??? No you can't.....

    So, OnlyMe, stop Pretending and learn, instead of taking shelter in English. And both of you please stop bluffing and let others learn...Prof Kaku is right, James is also right, Rpenner is fully on context, Tashja is politely leading the context, I am absolutely clear what I am writing, Brucep has withdrawn, so its time both of you showed some maturity and understanding of the subject.
     
    Last edited: Feb 13, 2015
  10. paddoboy Valued Senior Member

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    21,225
    It's far sadder that you still continually ignore all relevant aspects put to you, ignore the links and questions and just ramble on.
    Is this a "God botherering agenda you have, considering you don't even accept BHs exist? Is this just an exercise in trying to manufacture a BH paradox to support your anti science stance?

    Another untruth among many by Rajesh and his attempts to create paradoxes.
    Let me make it quite clear, besides myself and OnlyMe, no one has supported your stance, [and there has been maybe half a dozen posters comments having a giggle at your nonsense] and probably the reason they mostly stay away is due to your "unhinged" behaviour.

    Why start with a Neutron star? Why not just a very large star near the end of its productive fusion life?
    Let me tell you again, in no uncertain terms, until you can explain to the forum, how observed frame dragging can exist, but no rotating mass, then you have nothing...you are pushing shit uphill!

    The point singularity as agreed by all, does not exist.
    At some point, most likely at the Planck/quantum level [and as agreed to by at least one professor] the mass will exist in an unknown state.



    People have withdrawn because of your continued crap. They also withdrew when chinglu was preaching his anti SR/GR God botherering exercise.
    Rpenner has not made any comment re BHs in this thread as far as I know, and I'm certain James does not support you.
    But of course if I'm wrong he/they can all express their support for you. I await their reply in support.
    In short, like with most alternative hypothesis pushers, you appear delusional, and as I have expressed before , the methodology of yours in starting BH threads, taking a somewhat ignorant stance, quickly develops into some knowledge, and lopsided views.
    Finally, the only pretense is from you....Evident in your arrogance, your "demands"your ignoring of pertinent concepts, your ignoring of all links, and the obvious cherry picking from our professional people.
    Remember, no one, no link, no professor has ever said BH mass does not spin.
    They would not dare, as to say that is to fly in the face of accepted mainstream physics constants and principals.
     
    Last edited: Feb 13, 2015
  11. paddoboy Valued Senior Member

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    21,225
    "I think that to say that "the Kerr's ring singularity is spinning" is a fairly reasonable intuitive interpretation of the Kerr geometry.
    Kerr geometry has angular momentum, and it is reasonable (at least in some respects) to think of the ring singularity as the source of this angular momentum; and for this reason it is reasonable to interpret the situation as if the ring singularity is rotating.
    Best regards,
    Amos Ori

    http://www-conf.slac.stanford.edu/einstein/talks/kip-bhs.pdf


    "I don't know what it means to say that the "singularity spins" or not. The Kerr solution certainly has angular momentum---a notion that is well defined at infinity---and it would probably not be unreasonable to view the ring singularity as "producing" this angular momentum".
    Robert Wald:


    No Professor has ever said "A SINGULARITY DOES NOT SPIN"
     
  12. paddoboy Valued Senior Member

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    21,225

    Pot, kettle, black!!

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    Let me remind you how hypocritical and dishonest you obviously are....
    [1] You have said you do not believe BHs exist.
    [2] You have doubts on the conclusions and facts that once the Schwarzchild limit is reached, further collapse is compulsory.
    [3] You claim the density of a BH as a meaningful concept.
    [4] You claim frame dragging can/does exist with any rotational mass.
    [5] You argue strictly from the classical point singularity context [ despite probably not existing] , and refuses to recognise our models breaking down at the Planck/Quantum level and the beginning of the singularity, despite confirmation from at least one professor.


    ps: And that reminds me again of more of your dishonesty...From memory James' only comment so far in this thread was to support my claim which you doubted, re the Schwarzchild radius and compulsory collapse.
     
  13. OnlyMe Valued Senior Member

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    3,914
    Most of what you have posted is not worth responding to. It is almost as if you are trying to present some sort of math proof doused with intuition.

    BTW You could stuff to name calling and derogatory comments. Just stick to trying to coherently communicating what you think you know.

    Singularities do not appear. They are the location where the math and theory breaks down. They are mathematical anomalies, not real things.

    r ---->o is not the same as r = 0

    Rajesh, I don't think anyone has issues with the idea that the solutions we are discussing predict infinite densities and infinite or near infinite curvature, within the context of GR or infinite gravitational force from a Newtionian perspective. The point is that the fact that the solutions we have been discussing predict singularities, does not mean that they are describing any physical reality, in that context... Yet there must be a physical reality associated with what we have come to understand as black holes, or there is no reality at all. You are just stuck on some ground hog day loop, and confused.

    Black hole are real. Only you seem to deny that. And the singularities that result from vacuum space solutions are not physically real. You do understand that both the Schwartszchild and Kerr solutions begin to have problems, with reality at the event horizon and complete breakdown at the singularity. They may be able to predict the gravitational filed inside of the event horizon, at least up to the surface of what ever form the mass of the black holes winds up in.., which is not a mathematical singularity.

    This while it may be idealistically consistent with GR, assumes facts that are not covered by GR. That is why several responses have mentioned that some of the problems encountered in the solutions to EFE discussed, may be answered by some future model of quantum gravity. No one can say with any certainty that as a mass collapses it ever reaches a point where it overcomes the strong nuclear force.

    You are assuming too much. It sounds like you are trying to describe all of what is real, without all of the puzzle pieces in hand.

    No one has said you could. What has been said is that it is not unreasonable to assume the Kerr singularity has angular momentum...
     
  14. RajeshTrivedi Valued Senior Member

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    1,366
    We will play some board games on-line sooner......this science maths is quite a different ball game for you guys.
     
  15. paddoboy Valued Senior Member

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    Therein lies your problem. This is all a game to you, driven by an agenda, that has been evident from day one. You ignoring that claim and your other many short comings and interpretations, will not make them go away.
    They are there for all to see.
    And I'll keep raising them as long as is necessary.
     
  16. QuarkHead Remedial Math Student Valued Senior Member

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    1,502
    As a complete outsider, I should be interested to see an expansion of this.......
    And even more, this......

    \By edit.... Or to be more specific, the field equations that describe the undeniably "real" phenomena of gravitation are a set of 10 non-linear simultaneous equations that predict the existence of black holes.

    If it is the case that the available solutions to these equations predict singularities, how can it be that a "physically real" equation can have a solution that is not "physically real"?
     
    Last edited: Feb 13, 2015
  17. paddoboy Valued Senior Member

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    Welcome!

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    Not wanting to speak for OnlyMe but I suggest he is saying that the classical point singularity, with its infinities, as predicted, should not exist. Instead a mass of a particular size and dimension, maybe in line with the Planck/quantum level at which GR breaks down.


    In line with my previous thoughts. The classical point singularity is never reached, rather a surface of sorts probably at the quantum/Planck level.

    Over to OnlyMe!

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  18. OnlyMe Valued Senior Member

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    GR was originally intended to describe the graviationnal fields of known objects like planets and stars.., and it does a very good job within that context. Beyond that solutions to Einstein's equations have predicted black holes, and there is evidense supporting those predictions.

    There are two problems that these solutions encounter, the Schwartszchild and Kerr solutions being the simplest; The first occurs at the event horizon where it is predicted that the escape velocity equals and eventually exceeds the speed of light, which separates the gravitational field outside the event horizon from the mass used in the equations to describe the field. The second and even more troublesome is the predicted singularity itself. In over simplified lay terms and English, the singularity is a point mass with an infinite mass density and thus according to GR an infinite spacetime curvature arbitrarily close to the point mass/singularity, or in a Newtionian sense an infinite gravitational force. Looking at this from the Newtonian context is the most extreme, because if at any distance from the center of mass, the force of gravity were infinite, it would be infinite at all distances. For GR the problem only occurs at.., and perhaps arbitrarily close to.., the singularity, where the mathematics no longer makes sense. Just as example, it makes no sense because if you start with say 3 solar masses, which collapse into a singularity, the mass essentially disappears. No physical characteristics can be attributed to the singularity including mass... So where then is the mass that sustains the gravitational field? Once the singularity is reached it disappears from the equations.., or the equations begin to return unrealistic results.

    To the best of my recollection all professors responding to Tashja's question(s) have said in various ways that the singularity cannot be described as having any physical characteristics and even is not physically part of our reality... It is a mathematical science fiction as one put it. Several have added (and I paraphrase in my own words) that from an intuitive perspective there must be a physically massive object, where theory predicts a singularity and it, if consistent with all other experience, likely has angular momentum...

    GR does not account for any of the forces associated with the stability and structure of matter.., so there is nothing to oppose the colapse.., according to theory that occurs, just inside the event horizon... it is hoped that a successful model of quantum gravity will resolve these issues.
     
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  19. paddoboy Valued Senior Member

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    http://eagle.phys.utk.edu/guidry/astro616/lectures/lecture_ch18.pdf
    The no-hair theorem/conjecture: If gravitational collapse to a black hole is nearly spherical, – All non-spherical parts of the mass distribution (quadrupole moments, . . . ) except angular momentum are radiated away as gravitational waves. – Horizons eventually become stationary. – A stationary black hole is characterized by three numbers: the mass M, the angular momentum J, and the charge Q. – M, J, and Q are all determined by fields outside the horizon, not by integrals over the interior. The most general solution characterized by M, J, and Q is termed a Kerr–Newman black hole. However, – It is likely that the astrophysical processes that could form a black hole would neutralize any excess charge. – Thus astrophysical black holes are Kerr black holes (the Schwarzschild solution being a special case of the Kerr solution for vanishing angular momentum).
     
  20. brucep Valued Senior Member

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    4,098
    Read this about the gravitational singularity.
    http://en.m.wikipedia.org/wiki/Gravitational_singularity
    When they proofed the singularity theorem they described r=0 as the place where all geodesics end. As far as quantum gravity is concerned a quantum object can't occupy a space smaller than it's wavelength. So we can't have infinite spacetime curvature. Awhile back we had a thread which introduced two separate quantum gravity predictions. One where a shell forms just outside r=2M precluding the formation of a lightlike surface, event horizon, from forming. And the second paper predicted the shell would form at r=M. This is based on a requirement that the spacetime curvature is finite.
     
    Last edited: Feb 14, 2015
  21. tashja Registered Senior Member

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    715
    The gravitational field sustains itself. See Profs. Moore's and Rovelli's replies:

     
  22. OnlyMe Valued Senior Member

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    Tashja, could you link to the full statements for both. I am pretty sure both Moore and Rovelli would agree that gravity propagates at c.., and that the equations that describe a gravitational field require a non zero mass. The way those two comments are made, seems to me they have to be out of some greater context.., or both are saying that mass is not required to establish a gravitational field or that once established, the field is self propagating.., no mass is required. The only context I can imagine where that might be true is theoretical.

    I am not sure about Robelli, but I believe in an earlier response from Moore he made comment to the effect that some of the issues associated with the way GR treats black holes will be resolved by some future model of quantum gravity.

    BTW even in his statement above Moore does not entirely divorce the field from the mass that created it, though he addressed it in by comparrison to electromagnetic fields and angular momentum.
     
    Last edited: Feb 14, 2015
  23. OnlyMe Valued Senior Member

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    Bruce is correct here and when I said spacetime curvature could be infinite arbitrarily close to the singularity it was an error. The point I was trying to make was the distiction that Newtonian gravitational force could not recover from infinity, where I believe The curvature of spacetime in GR is not as limited.
     

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