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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    Here are two scientific papers, one by Roy Kerr himself, after which the spinning BH is named.



    http://www.astro.sunysb.edu/rosalba/astro2030/KerrBH.pdf
    where it says in describing the ergosphere and frame dragging.......
    "Because spacetime is “stuck” to the horizon, space is
    dragged along with the spin. This appears as a tornadolike
    swirl in hyperspace".

    and also.....
    "A spinning black hole modifies the fabric of spacetime
    near it, allowing matter to orbit at a closer distance than if the black hole were not spinning".

    Now perhaps our troubled soul with his questionable antics about BH's and their properties, should ask himself in relation to the second quote, what does a "spinning BH" mean. Or what parameters define a BH.
    I'll answer for Rajesh anyway....
    A BH is defined by the EH and whatever condition exists at the center. Important issue of course being the EH.

    Will we have further confrontational, nonsensical, anti BH sentiment again pushed in the guise of questions already answered?
    Sadly, most probably.
    In essence the tirade in this thread, is now reaching the cesspool standards of that started by theorist constant and chinglu and should in all fairness be questioned and actioned.





    and another scientific paper.....


    http://www.eftaylor.com/pub/SpinNEW.pdf
     
    Last edited: Jan 15, 2015
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  3. RajeshTrivedi Valued Senior Member

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    You are a sweetheart !!
     
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  5. RajeshTrivedi Valued Senior Member

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    Infact the file which I attached is from KerrBH only, the same picture from where you copied and pasted....Can you figure out the no Frame Dragging on the inner side ?? Slightly difficult.

    So, now please refer to your second link of Chandrasekhar..at the Page # F8 Fig 1......you can easily figure out that frame dragging is present and conceivable only in Ergosphre (the shaded part)...not in the section wherein (r/M < +/- 1). Even otherwise think by definition of EH, the arrow is spatially unidirectional..the curvature is infinite...so nothing can drift or drag........Yes there is a huge amount of Frame Dragging in ergosphere and even outside...Frame Dragging formulas are available even with respect to Gravito-magnetism which are somewhat different from relativity calculations. [just a passing reference to GEM for clarity]

    So don't you think you and your friend Brucep are factually incorrect in saying that entire Kerr Geometry spins, even the inner part. At least you are providing some camouflaged links to wriggle out, he has just vanished and has no intellectual strength to come forward and state the true position....thats what I call true intellectual dishonesty....like true singularity at r = 0.
     
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  7. Jason.Marshall Banned Banned

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    lol don't mind me am just ease dropping this is entertaining you will not know what am thinking.
     
  8. RajeshTrivedi Valued Senior Member

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  9. RajeshTrivedi Valued Senior Member

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    Paddoboy

    Now of course, you can appreciate the question.....The entire Rotational Energy of Kerr BH is associated with ErgoSphere (shadow region in Fig 1 of your link)...This is ok as Energy can be associated with region...but Angular Momentum can only be associated with Mass, which is at singularity and we know nothing about that....So what is the true meaning of Angular Momentum of Kerr BH ??
     
  10. Jason.Marshall Banned Banned

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    The singularity is beautiful.
     
  11. paddoboy Valued Senior Member

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    All factual links despite your dishonest interpretations.
    The Kerr geometry spins totally, if it didn't we would be throwing common sense out the window.
    Obviously with the half a dozen or more errors you have made with regards to BH's this is probably the most obtuse.
    TheIntellectual dishonesty rests squarely on your shoulders.
     
  12. wellwisher Banned Banned

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    Nobody seems to answer this question. With decreasing radius and a fixed mass, conservation of angular momentum requires it spin faster and faster like the skater pulling in her arms. The surface of the mass cannot reach the speed of light, unless infinite energy is added, which we don't have. We may not be able to reach a point, unless we add external energy to approximate infinite energy.

    According to SR, the motion of mass will cause the relativistic mass to increase. Does the energy in the angular momentum partially go into relativistic mass, thereby limiting the final angular speed? Energy conservation will trump conservation of angular momentum. Is this particular version of relativistic mass the same as dark matter, since it will persist if the angular momentum is conserved?
     
  13. OnlyMe Valued Senior Member

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    That seems to be an inaccurate and misleading statement. Have you actually read the whole of the link you provided? http://www.eftaylor.com/pub/SpinNEW.pdf

    The diagram at the top of page F-14 shows the path of a stone dropped toward a spinning black hole. The stone has no intrinsic angular momentum but, the path it takes suggests that the space it travels through does!

    Equation [22] gives the remarkable result that a particle with zero angular momentum nevertheless circulates around the black hole! This result is evidence for our interpretation that the black hole drags nearby spacetime around with it.
    From page F-14 of the same link

    You seem to keep claiming that only mass has any angular momentum when discussing a spinning black hole. This can be true if you think of the black hole only as the central mass.., but is that an acurate and true conceptualization of what is going on?

    What is being presented in that text, can be interpreted from many different frames of reference. The fact that it describes the space near a spinning black hole as being drug around by the angular momentum of the black hole, suggests that you can chose a coordinate system or frame of reference from which the space itself has angular momentum. This is what I believe is being suggested in Fig. 5 on page F-17, where each ring is shown to have different angular rates. Whether they are viewed as rotating around the black hole or having angular momentum associated with the involved space is a matter of frame of reference.

    I got a little carried away there, the point is that your statement in bold above is entirely false since your reference attributes the angular momentum to the mass of the black hole and depicts the ergosphere as a volume of space, which may include massive objects, that rotates around the central spinning black hole.., as a result of frame-dragging associated with the spinning black hole. In some respects one can treat the ergosphere as an object itself, or an extension of the physical system of the black hole, and as having angular momentum itself. It all depends on the frame of reference you choose. But in either case the ergosphere is not a solid object composed only of mass. It is a region of space...

    There is a completely different question regarding space and frame-dragging that emerges from both the mathematics of Kerr black holes and the evidence obtained from the GP-B experiment. Both suggest that we must at least consider the possibility, that any space associated with any regular motion, of any massive object, does over time accumulate intrinsic momentum of its own..... Which leads to a whole other discussion about the dynamics of large inertial systems.., like solar systems, galaxies and galactic clusters.... Which is beyond the discussion here.
     
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  14. OnlyMe Valued Senior Member

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    It would be good to forget the idea of relativistic mass and just talk about momentum.

    That issue aside the answer is similar to the one I gave earlier. As long as the object you are talking about is macroscopic, meaning composed of atoms or even protons and neutrons, as we expect is the case for neutron stars, or even quarks.., and does not lie within the event horizon of a black hole, inertial resitance to acceleration will limit the angular velocity, regardless of what we believe the fundamental origin of inertia is...

    Inertial resistance is proportional to acceleration. Thus the angular momentum of any object, other than a fundamental particle (electrons and quarks...), can be viewed as each component part accelerating relative to a common frame of reference, the object's center of mass. For fundamental particles the mechanism of inertia itself, may become important to the issue of speed of light limitations and angular momentum.

    Your question here and earlier suggests you are having some difficulty understanding the relationship between inertia, acceleration, momentum and the speed of light as a limiting velocity.... Which does require some fundamental understanding of just what inertia is... Something that is not fully understood or settled science at this time.

    There are theoretical approaches that attempt to explain an underlying fundamental mechanism from which inertia emerges, but none that I am aware of are without inherent unresolved difficulties. Which leaves any answer subject to theoretical assumptions about inertia.

    So, to be entirely clear, I don't believe anyone can give you an answer that is more than speculation... Other than, the one I began this post with,
    It would be good to forget the idea of relativistic mass and just talk about momentum.​

    The mass of protons accelerated to near speed of light velocities, does not increase. Their momentum, and inertial resistance to further acceleration does.

    The question you are asking is one that theoretical physicists struggle with, and I don't believe anyone has an answer that is not either just speculation or limited by the theoretical basis they begin with.
     
  15. paddoboy Valued Senior Member

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    I see it simply as a physical extension of the BH itself, and being just a region of space, or spacetime, it is glued to, [ for want of a better word] or just an extension of the spacetime that exists on the inner side of the EH, or the BH itself.

    In taking this claim of Rajesh's further, it appears to me it is absolutely against the laws of physics, GR and logic to claim that "frame dragging" [ergosphere] exists, and then in the same breath claim that the spacetime that makes up the spinning BH, which is necessary to facilitate frame dragging, does not spin at all, but the singularity [mass] is spinning, and as a consequence, forms into a ring.
    In essence Rajesh is saying that the spinning mass, facilitates frame dragging of spacetime, [ergosphere] which is a Schwarzchild radius away from the mass [ring singularity], while the intervening spacetime which makes up 99.9999% of the BH, is not spinning.

    Please Register or Log in to view the hidden image!

     
    Last edited: Jan 16, 2015
  16. paddoboy Valued Senior Member

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    Not sure of the answer, but when the outer and inner EH's merge due to increased angular momentum, they shrink toward the ring singularity and expose it as the EH vanishes.
    But I would probably invoke the "cosmic censorship hypothesis" and nature's abhorrence for a naked singularity as some universal law limiting spin. Although our knowledge in this regard is rather flimsy and I'm only actually guessing.
     
  17. KilljoyKlown Whatever Valued Senior Member

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    It just occurred to me that when tw0 BH's merge and one is a SMBH and the other is a stellar size BH and the smaller one falls into a tight orbit around the big one. Could the little one become tidally locked and not have any spin at all?
     
  18. tashja Registered Senior Member

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  19. paddoboy Valued Senior Member

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    Vinaka vakalevu tashja!
     
  20. OnlyMe Valued Senior Member

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    Tidally locked does not necessarily mean no spin. Our moon spins. It just does so such that one side always faces us.
     
  21. KilljoyKlown Whatever Valued Senior Member

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    We aren't talking much rotational energy here. I'm not sure it's even possible for a small stellar BH to become tidally locked, but if it could be, it would be very close to being a true Schwarzschild black hole.
     
  22. brucep Valued Senior Member

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    You're just hypothesizing bullshit. Pay attention then review for yourself. It's conservation of angular momentum.
    Read the project. The frame of reference is just like any other relativistic physics. You have local proper coordinates and remote coordinates. Everything covered is derived from the Kerr metric. In this spacetime geometry the angular momentum sums to the mass of the black hole as mass. IE: If it was a spherically symmetric non rotating black hole of one solar mass spun up to an extremmal Kerr rotating black hole the angular momentum adds another solar mass. If it had extremmal charge then it would sum up to three solar mass. The frame dragging effect is associated with the spinning spacetime. Look at the project on the page where it compares the Schwarzschild constants of motion with the Kerr constants of motion [equations of motion] and solve equation [21] for L/m = 0. That means the angular momentum is 0 and the frame dragging is angular velocity derived from the spinning spacetime. It's all there but you actually need to follow the derivations from the metric to get an understanding for the prediction.
     
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  23. brucep Valued Senior Member

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    Good observation. I would be guessing it would be a 'very long winded' Killjoy Klown process.
     
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