Neutron Star

Discussion in 'Astronomy, Exobiology, & Cosmology' started by RajeshTrivedi, Apr 7, 2015.

  1. RajeshTrivedi Valued Senior Member

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    True, so far all the observations of Neutron Star are in the range of around 1.4 to 1.9 Solar Mass and radius around 10-12 Kms..........my conclusion is not against this, infact the range I have shown is 1.4 to 2.65 at least for a visible NS.

    1. That a visible Neutron Star (outside Event Horizon) can exist only in the range 1.4 to 2.65 Solar Mass.
    2. A visible Quark Star (not all Neutrons in the core as Rp>Rn) can exist only in the range 2.65 to 3.24 Solar Mass.
    3. But there is a possibility...of an object.....which can exist larger than 3.24 Solar Mass and inside EH (Rs > Rp) ...and I have called that as Black Neutron Star (BNS).
     
    Last edited: Apr 8, 2015
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  3. OnlyMe Valued Senior Member

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    That is pure speculation Rajesh.

    The exact composition of the core of a neutron star is theoretical and even then most theororetical models do not suggest that the core contains only neutrons. The core is theorized to contain anything from, exclusively neutrons, to a mixture of neutrons and protons.., even sometimes containing heavy nuclei. It all depends on who is writing the theoretical paper... And that is just the core. The star itself in almost all models has layers of different compositions, ending with a crust of dense ordinary matter. Some models don't even speculate on the composition of the core...

    So how do you justify, limiting the neutron star's composition to the most extreme speculations about what the core composition might be like?

    It seems to me that what you are presenting is some what like a house of cards built from speculation based on speculation. Somewhere you need solid ground to set a foundation. Generally when gravity is involved, GR is that solid ground. In some respects this can be seen as one of the difficulties, that a successful QTG faces.., QT and GR don't get along to start with. Again, it seems you are tossing GR out as a foundation and not presenting any alternative, so you wind up with speculation based on speculation.
     
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  5. OnlyMe Valued Senior Member

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    Rajesh, unless and until you provide a workable alternate to GR, the above is not even science fiction. GR predicts that the event horizon is the line in the sand where gravity overcomes even the strong nuclear force and colapse to a black hole is unavoidable!

    I am not convinced that this is a true picture of reality, but it is the best model of gravity we have at this time.., and it does describe gravitational fields outside of an event horizon very well... So what you are suggesting above cannot be a description of what is real unless and until you provide a better description of graviation than GR. A successful QTG is our best hope for that and it is a long way from successful, at present...
     
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  7. RajeshTrivedi Valued Senior Member

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    We do not know the exact nature of the matter inside Neutron Star...this is a fact and lot of research available which even touches upon superconductivity....

    But let us understand what the theory is....about the matter inside the and about the formation of Neutron Star....

    1. A normal star can fuse exothermic only upto Fe
    2. Beyond that if core is heavier, than Gravity is balanced by EDP....a WD is formed if core < 1.4 M.
    3. Once the core > 1.4 M, and if the Gravity persists then these electrons tend to become relativistic as per Heisenberg uncertainty principle and are captured by protons (so called reverse beta equation) and Neutrons are formed, thus the innermost core is nothing but a majority of Neutrons only...original + e/p converted.

    So as per present theory.... a Neutron Star core contains mostly the Neutrons only and of course some residual protons...........my paper is based on this all Neutron aspect only, which is more or less how NS is theorized.
     
    Last edited: Apr 8, 2015
  8. RajeshTrivedi Valued Senior Member

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    There are two points in your argument which need further clarification from you...

    1. Can you please pin point which part of GR says that gravity overcomes strong nuclear force......at least I have not encountered such description of GR in any paper...in fact GR does not depict gravity as force.

    2. What do you expect from QTG ? I mean what do you think QTG should offer ??
     
  9. origin Trump is the best argument against a democracy. Valued Senior Member

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    OOPS! I read your .55 fm as a diameter not a radius. That in no way implies that I think your idea has merit, just acknowledging my error.
     
  10. OnlyMe Valued Senior Member

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    The answer to #1 is straight forward. #2 is a matter of faith, that we will overcome the divide that currently exists between GR and QM (and a successful QTG).
    1. The simplest example is the Schwartzschild solution, but in all solutions to EFE the end result is a singularity. That does not directly state that gravity overcomes the strong nuclear force.., but it is implicit in the end result. You could not arrive at a singularity if gravity does not overcome all QM forces, including the strong nuclear force. So unless (or until) we come up with a better description of gravitation than GR, even if that is only a description that accounts for gravitation at a quantum level and transitions to a form consistent with GR at macroscopic scales and outside of an event horizon.., we are stuck with the singularity.
    2. I believe that there will be a conceptual change in how GR is understood (and QM for that matter), which allows for a conceptual revision of the fundamental mechanism of gravitation (there is no known fundamental mechanism at present), such that a successful QTG will be able to both describe the structure/composition of mass inside what we now refer to as an event horizon (without a singularity) and a fundamental quantum mechanism that can bridge the gap between GR's macroscopic description of gravitation and both gravity at a quantum scale, as well as within what we currently understand to be (and describe as) a black hole.
     
  11. danshawen Valued Senior Member

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    This is nice, and I approve of the publication of it.

    But it's a fact, in a thread since I joined in June 2014 when I joined last year, this topic came up for discussion.

    I recall I suggested the idea that several neutron star masses created by the usual Chandrasekar limit (white dwarf-electron degeneracy) method could coalesce into a larger mass which would collapse further into a black hole. After such a collapse, no difference would be observed between a neutron star mass formation of a black hole and any generic collapse of masses greater than that of the Chadrasekar limit.
     
  12. Q-reeus Valued Senior Member

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    Rajesh, it would have saved you much time, effort, and moderate expense, to have first thought through the basics better. It's not logically possible to at one and the same time accept GR as true yet claim an imaginary stable (or metastable) 'black NS' can just somehow sit there inside of EH. If you accept GR is true then you must accept the predictions of exterior Schwarzschild metric as the unique solution of EFE's outside of a static and neutral spherically symmetric matter distribution.

    If as your scenario has it such matter has symmetrically collapsed to inside the EH, then regardless of any imagined interior situation, we have an exterior BH spacetime right down to the actual EH. And it's well known the 'g-forces' required to maintain a particle static at EH are infinite:
    https://en.wikipedia.org/wiki/Event_horizon#Interacting_with_an_event_horizon (fourth para re 'lowered rope')

    Ipso facto, a hypothetical, stationary gossimar thin spherical shell of matter there (and further in) would exert 'at least' infinite pressure on anything at lesser radius trying to keep such gossimar thin shell propped up. Say for instance an imaginary Dark NS. Which itself can be considered an onion-layered collection of anything-but gossimar thin shells - all at lower gravitational potential than EH hence all exerting 'greater than infinite' g-forces on the next inner layer (hypothetically - assuming static structure)!

    Start to get the picture - the utter impossibility of your imagined stable Dark NS? The only logical solution within GR is therefore unrestrained collapse all the way down. The usual picture. Unless you can endow your Dark NS with greater than infinite compressive strength! And that still leaves out of consideration the added runaway collapse situation owing to pressure acting as a further source of gravity in GR. Sorry chum - time to gracefully quit and go back to the drawing board.
     
  13. OnlyMe Valued Senior Member

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    Dan, what Rajesh is suggesting is that there are no black holes.., or he has in the past! His current hidden (my word) or black neutron star, is essentially a resurrection of the frozen star or something similar.., and he doesn't explain how or why GR works outside the event horizon and does not work inside.

    I don't have a problem with looking for a solution to the singularity problem, or the problems that a singularity raises for both GR and QM. And I do believe that there must be some real mass with physical dimensions and characteristics associated with what we currently think of as black holes, but we cannot get there by just saying it is so without providing the bridge between our current understanding of GR and whatever the eventual solution is.

    I don't know the answer, but I suspect (and have mentioned the possibility in past threads), that what we think of as an event horizon is not defined by an escape velocity of c, but instead by a state of matter that no longer supports the emission of detectable EM radiation. It would be black and and likely also supress all other significant atomic and subatomic processes, without ever reaching or requiring the speed of light escape velocity or singularity... But that is pure and wild speculation...
     
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  14. brucep Valued Senior Member

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    It's a consequence of the Pauli Exclusion Principle. Do yourself a favor and learn what that is. GR doesn't make any predictions associated with quantum physics domain of applicability. Do yourself a favor and learn what that means. So GR doesn't predict the exclusion principle. Wolfgang Pauli does using quantum physics. The strong nuclear force is what holds the nucleus of the neutron together. Learn what degenerate matter means. If you have to ask those questions why are you writing a paper on something you don't even know basics about? I'm going to look for one of the quantum gravity papers that predict the spacetime curvature at r=0 is finite which results in a shell at r>2M. You can try to read that. This is a paper that uses quantum gravity to analyse the gravitational collapsing star. It predicts the black hole event horizon never forms. The details are in the paper. I don't put much stock in this since we've observed the dying pulse train predicted by GR. Specifically at the black hole Cygnus x-1. I've read a similar analysis which predicts the shell forms at r=M. They're essentially doing these analysis in a Schwarzschild spacetime. IE a spherically symmetric non rotating spacetime.
     
    Last edited: Apr 8, 2015
  15. RajeshTrivedi Valued Senior Member

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    Brucep / OnlyMe...

    1. GR and for that matter formation of BH has got nothing to do with Nuclear Force.....it was not a question by me, it was a pointer to both of you, that please show where in GR (or even during formation of BH) how Gravity overcomes Nuclear Force, since Brucep wants me to read about Degenerate matter, I presume he has already read, but if he has understood he would know that Nuclear Force-Gravity tussle in the implied manner is no longer associated with any of those concepts around NS.....He may find it difficult to retract but thats how the theory is..

    2. Again both of you (and James too) avoided answering expectations from QTG.....

    You (including Paddoboy) are saying as and when we get QGT, may be we will be able to resolve BH singularity....fine but in your opinion what are we expecting from QGT ??
     
  16. RajeshTrivedi Valued Senior Member

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    (The colored quote) This is interesting......but the problem is collapse to Unknown/Singularity....

    Now as per me our expectation ( a question open for you also) from QGT is to come up with some kind of Quantum Mechanics Mechanism which can counter the Gravitational Pressure, thus resulting into a stable object inside the EH.......so in reality our expectation from QGT is something which will avoid singularity but possibly give a dimensional object inside......Technically GR will be violated but we can always say that GR is not violated, it is just that we are working on a QM domain...but nonetheless we are expecting a stable mass domain inside BH from QTG.

    Now what I have suggested calls for some understanding of few points with respect to collapse inside EH...

    1. Gravitational Pressure is present inward to force collapse if not countered.
    2. Our NDP calculations yield mass range of around 2-3 Solar Mass and radii around 10-12 Kms. I have not seen any NDP calculations for a one million star core. (Bigger Cores)
    3. But as the mass goes up....say for a million solar mass, the EH is very big around 3 million Kms and NDP can only be stated to be completely overcome at around 650 Kms.......so there is a possibility of counter balance by NDP.....thats the point I am making.
    4. This point makes sense in a different context as well....as the mass increases the Rs increases (density getting inversely proportion to Rs^2) thus giving more space to Neutrons etc to move around from the start of collapse at EH, so certainly it cannot be stated that NDP is overcome at r > Rs (outside EH).......the possibility of NDP getting overcome is inside EH only for mass > 3.24 M..

    PS : No I am not suggesting that there are no Black holes....I am just suggesting what might lie inside EH.
     
  17. RajeshTrivedi Valued Senior Member

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    Are we not expecting anything stable inside EH from QTG ? If so then as per you it will also violate GR ? If you think otherwise pl let me know what you expect out of QTG ??
     
  18. RajeshTrivedi Valued Senior Member

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    Thank you !!

    You are right as on date once the core is inside EH, it does not make any difference. Why I have termed this as Black Neutron Star is that........it is inside EH (so it may be called as Black....) and since its due to NDP creating hydro static balance with Gravity and hence Neutron Star...
     
  19. James R Just this guy, you know? Staff Member

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    RajeshTrivedi:

    Questioning the standard of peer review of the journal in question has relevance in so far as we don't know what kind of independent expert scrutiny your paper has been put to. Since most people here are non-experts in the particular fields that are most relevant to the paper's content, it would be nice to know that at least some independent experts have approved your paper.

    Since we don't really have a quantum theory of gravity, it is hard to know what to expect. It seems unlikely that the interior black hole solutions provided by GR will be completely negated by a QGT, but I admit that is really a guess. You're relying on the opposite hunch, but it's still an unproved assumption.

    I admit I'm no expert on this. Do you have any reason to suspect that a QGT will provide a mechanism to allow for your dark neutron star, or are you just speculating?

    Even if there is no singularity at the centre of a black hole, there are a lot of possibilities between that and allowing for the existence of a neutron star inside the event horizon, as you describe. In the absence of a singularity, there may still be a "tear" in spacetime that leads through to other universes or whatever. It does not seem to me logically necessary that the interior of a black hole should be able to support any kind of macroscopic object against gravitational collapse.
     
  20. Q-reeus Valued Senior Member

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    The hugely speculative proto-QTG predictions (mostly from the LQG crowd) of a 'repulsive force' (super-duper infinitely strong apparently) countering GR classically unstoppable collapse to a point singularity, only kick in at around Planck length. What does that have to do with your published notion of a stable black NS - obviously of typical NS dimensions since you have it comprised of neutrons, or perhaps free quarks. Chalk and cheese. There has been hugely speculative ideas of e.g. Black star, Gravastar, (see under listing here: https://en.wikipedia.org/wiki/Hypothetical_star). The latter forms just outside the EH, and many believe it not stable against minor perturbations though there is heated debate and counterarguments. I think it's nuts.

    Do you or do you not accept my basic argument in post #29 re your imagined black NS - the one you published on? Despite what another poster has said, there is no logical escape to that scenario within GR - only some hopeful extreme presumed to be at Planck scale, as mentioned before.
     
  21. RajeshTrivedi Valued Senior Member

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    James R

    Fine, a tear in spacetime is an extended solution based on GR only, not in the domain of Quantum Mechanics. If we are looking for some solution around QTG, then it got to be in our universe only.......Under QTG I see no reason, not to believe why it cannot be under some known or unknown particle/energy Physics.

    I have simply offered that inside EH there is a possibility of Degeneracy Pressure countering the Gravity.......the object can be termed as anything
     
  22. RajeshTrivedi Valued Senior Member

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    Let me search some Proto QTG research around Planck's Length which speculates such force......may be you can provide a link for that..
     
  23. Q-reeus Valued Senior Member

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    Instead of trying to somehow salvage your published black NS concept, don't you think it best to simply give it up as a mistaken notion? Yes hard to take but necessary if you wish to be honest with yourself.

    IF the LQG crowd's complex calculations of repulsion and even a bounce back out from ~ Planck length are ultimately founded on fact not fantasy, that all comes from quantized spacetime - IT HAS NO BEARING ON OR CONNECTION WITH DEGENERACY PRESSURE IN A NS! Which owing in part to the softness of the ultra-relativistic EOS, has a quite finite limit and cannot therefore resist the infinite pressures which GR inevitably predicts. Do you want to invoke magic, instead of living with consensus established physics? Accept GR - then accept the impossibility of black NS.
     

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