Black Hole.... Not so Black

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

  1. RajeshTrivedi Valued Senior Member

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    matter is gravity...spacetime distortion is gravity.....a black hole has gravity.....not even light can escape BH...

    These are all fine, present theories...

    The point is that inside BH, atomic structure is not present, electrons are also captured by protons, neutrons are also gone into lowest energy state, and further compression is also envisaged thus leading to quark star and Preon Star (?) and singularity.....How do we know about the nature of Gravity when electrons, protons and neutrons (and whatever ~0n) all have gone ?? I feel somewhere in this gravitational compression journey from a normal star to BH....Gravity itself will give up and blasttttt outward....it can be kind of alternating to some extent, compress... blast...compress...blast...compress... (Innermost matter gravity vanishes beyond certain point, then G pressure reduces and outwardly fermi pressure takes control, again G pressure takes control and it goes on till it is no longer viable for G pressure to take control again...
     
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  3. paddoboy Valued Senior Member

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    My only criticism to that James, is that you fail to mention spacetime.
    Spacetime is curved in the presence of mass/energy, which then exhibits the effects we call gravity.
    And since spacetime was what evolved from the BB, with matter/mass coming later, in my humble opinion, gravity appears to be more associated with the geometry of spacetime then it does with mass.
     
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  5. OnlyMe Valued Senior Member

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    Paddoboy, that doesn't make sense. Take a few and rethink all of the implications of what you just said... There are a lot of assumptions, in there.

    However, the fact that we have no evidence that gravity exists without the presence of mass, seems to be in conflict with your conclusion. Even in the case of effects associated with gravitation and dark matter, we assume some mass that has as yet to be identified.

    Spacetime as described in the context of GR does seem to be associated with gravity, but the exact certainty of the nature of that association, has not yet been fully established...
     
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  7. paddoboy Valued Senior Member

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    I make no assumptions.
    I'm simply saying that gravity exhibits itself, when spacetime is curved/warped in the presence of mass/energy.
    The BB was the evolution of spacetime in the first instant....Matter came later.
    Gravity is simply spacetime, shaped in the presence of mass/energy.

    Spacetime tells matter how to move: Matter tells spacetime how to curve.

    From those facts, I see spacetime as critical to gravity as is mass.
     
  8. OnlyMe Valued Senior Member

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    The following portion of your earlier post implies that since spacetime predates the existence of matter/mass, and gravity is simply spacetime... that gravity predates the existence of the matter/mass, it seems to depend upon today.

    This is one of the issues I have with the conceptual model invoking the curvature of spacetime as the cause of gravitation. While spacetime within the context of GR certainly is a description of gravitation, it doesn't really explain the cause, or fundamental origin of gravity.

    The phrase, "Spacetime tells matter how to move: Matter tells spacetime how to curve.", is catchy but also misleading. It is an imperfect lay description of a dynamic interaction that does not lend itself well to plain language. The word "tells" in that phrase lends a conceptual meaning that is not present in the math. It implies causation or some indication of a fundamental origin.

    The conceptualization that goes along with that catch phrase is a modern interpretation of GR and even then, one that cannot be reconciled with QM and any present rendition of quantum gravity. It even requires some significant hoop jumping to keep up with observational evidence at cosmological scales.

    It sounds good, but by itself it does not really say much. Most catch phrases have that in common.
     
  9. OnlyMe Valued Senior Member

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  10. paddoboy Valued Senior Member

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    Ahah! Now I see what you are referring to.
    This is the way I see it [rightly or wrongly]
    Keeping in mind we know nothing for certain about the first 10-43 seconds, from my understanding, when spacetime did evolve from the BB instant, all the forces were melded together in what was called the "Superforce"
    So, according to that, and for that first instant, gravity per se did not exist.
    .
    As the spacetime underwent expansion, temperatures and pressures dropped and the Superforce started to decouple, with gravity being the first.
    So in essence, everything, matter/mass, gravity etc, all evolved from spacetime.

    To put all that another way, it took a short time after the BB for the first fundamental particles to evolve, just as it took a short time for gravity to decouple from the Superforce.
    And remembering also that although light also affects spacetime curvature by a tiny amount and subsequently gravity, yet it has no rest mass that we know of.
    A further pertinent fact is that the nonlinear property of spacetime/gravity, means that gravity also creates gravity, albeit again by a tiny amount.



    I also see the following statement by Sten Odenwald, as in line with those thoughts......
    Experiments continue to show that there is no 'space' that stands apart from space-time itself...no arena in which matter, energy and gravity operate which is not affected by matter, energy and gravity. General relativity tells us that what we call space is just another feature of the gravitational field of the universe, so space and space-time can and do not exist apart from the matter and energy that creates the gravitational field. This is not speculation, but sound observation.



    It's well accepted we do not know the underlying reality of why gravity exhibits itself when spacetime is curved in the presence of mass/energy.....The same as we do not as yet know the cause and the why of the BB.
     
    Last edited: Oct 26, 2014
  11. James R Just this guy, you know? Staff Member

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    At the big bang, there was an awful lot of energy in a small space, which meant very large spacetime curvature. Even there, it was the energy/mass that determined the spacetime curvature.
     
  12. paddoboy Valued Senior Member

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    OK, that makes some sense, realising of course that no mass in the form of matter was created until a small time after the initial event.
     
  13. river

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    Of course no mention of magnetic fields here , from these so called BH

    Note this though ;

    NEWS CENTER

    Surprisingly Strong Magnetic Fields Challenge Black Holes’ Pull
    Analysis of radio waves from black holes shows long-neglected magnetic fields have an unexpected presence.
    News Release Kate Greene 510-486-4404 • JUNE 4, 2014
    152

    7 7
    A new study of supermassive black holes at the centers of galaxies has found magnetic fields play an impressive role in the systems’ dynamics. In fact, in dozens of black holes surveyed, the magnetic field strength matched the force produced by the black holes’ powerful gravitational pull, says a team of scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany. The findings are published in this week’s issue of Nature.

    “This paper for the first time systematically measures the strength of magnetic fields near black holes,” says Alexander Tchekhovskoy, the Berkeley Lab researcher who helped interpret the observational data within the context of existing computational models. “This is important because we had no idea, and now we have evidence from not just one, not just two, but from 76 black holes.”

    Please Register or Log in to view the hidden image!


    A computer simulation of gas (in yellow) falling into a black hole (too small to be seen). Twin jets are also shown with magnetic field lines. Image credit: Alexander Tchekhovskoy, LBL

    Previously, Tchekhovskoy, who is also a postdoctoral fellow at the University of California, Berkeley, had developed computational models of black holes that included magnetic fields. His models suggested a black hole could sustain a magnetic field that was as strong as its gravity, but there was not yet observational evidence to support this prediction. With the two forces balancing out, a cloud of gas caught on top of the magnetic field would be spared the pull of gravity and instead levitate in place.

    The magnetic field strength was confirmed by evidence from jets of gas that shoot away from supermassive black holes. Formed by magnetic fields, these jets produce a radio emission. “We realized that the radio emission from black holes’ jets can be used to measure the magnetic field strength near the black hold itself,” says Mohammad Zamaninasab, the lead author of the study, who did the work while at MPIfR.

    Other research teams had previously collected radio-emission data from “radio-loud” galaxies using the Very Long Baseline Array, a vast network of radio telescopes in the United States. The researchers analyzed this pre-existing data to create radio-emission maps at different wavelengths. Shifts in jet features between different maps let them calculate the field strength near the black hole.

    Based on the results, the team found not only that the measured magnetic fields can be as strong as a black hole’s gravity, but that they are also comparable in strength to those produced inside MRI machines found in hospitals–roughly 10,000 times greater than the field of the Earth itself.

    Tchekhovskoy says the new results mean theorists must re-evaluate their understanding of black-hole behavior. “The magnetic fields are strong enough to dramatically alter how gas falls into black holes and how gas produces outflows that we do observe, much stronger than what has usually been assumed,” he says. “We need to go back and look at our models once again.”

    ###

    Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.
     
  14. paddoboy Valued Senior Member

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    The question was not about whether a BH has a magnetic field or not.
    The debate was about theoretical quantum effects, and what they assume about a BH.
    The best evidence supports the existence of BH's and there reality is not really in question, despite sensationalistic headlines.




    Yep interesting....
    And the research continues into "Kerr Newman"and "Reaisner-Nordstrom" BH....
    It's worth noting though, that both the properties of spin and magnetic field are thought to be negated over time, leaving of course gravity to rule the roost, so to speak.
    And of course it is not the twisted magnetic fields that give rise to the BH in the first place, it is the BH and its associated spin and charge that give rise to the twisted magnetic field lines.
     
    Last edited: Dec 10, 2014
  15. Q-reeus Valued Senior Member

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    Pertinent fact? According to most holy GR? In your head it may be - paddoboy. Get used to the perils of blindly/mindlessly quote mining your fav GR heroes. It's true in this case that authorities differ on whether 'gravity gravitates' i.e is partly it's own source. But those truly in the know, know that according to the EFE's, gravity does not gravitate. Mere non-linearity is not indicitive of 'gravity gravitating' Try and get your 'pertinent facts' right before spouting that which you do not really know - paddoboy. Do your own research, try and get a basic understanding of what the EFE's imply (not much hope for that, but it's what you need to do). And if you need a link establishing what I say, just ask - politely though.
     
  16. paddoboy Valued Senior Member

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    Oh grow up, and don't try your bullying tactics with me....
    I certainly don't mind standing on the shoulders of giants, both present and past, you just happen to be a midget.
    And yes, I do think for myself, and am quite capable of sorting the wheat from the chaf.

    In the meantime gravity is non-linear, and gravity makes more gravity.
    The gravity of gravity
    http://www.einstein-online.info/spotlights/gravity_of_gravity

    One reason why the physics of general relativity is much more difficult than that of Newton's theory of gravity or the theory of electrodynamicsis a property called non-linearity. In short, gravity can beget further gravity - where gravitational systems are concerned, the whole is not the sum of its parts.

    more....
    http://www.einstein-online.info/spotlights/gravity_of_gravity
    ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::


    Now seriously, if you want to assault GR like our other anti science nuts, then go to the alternative section.
     
  17. Q-reeus Valued Senior Member

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    Bullying tactics? LOL - that's a bit rich coming from you!
    No, you don't, and you can't, as evidenced by your reliance on quote mining - as per below.
    I did specifically note that authorities differ on this one. But typically you just ignored that.
    Assault GR? You falsely accuse me in this case. In this case it's a matter of understanding what GR actually says. And your bullying directive will be ignored as it should be. Try broadening your search - paddoboy. I said search rather than research because you are capable of precious little of the latter. By search I mean objectively - not just selectively grab-bagging every quote supporting your prejudice. And like I said, if you really do get stuck, ask *politely* and I will furnish a link or links to material backing my claim. That you (and author of above) are simply wrong.
     
  18. paddoboy Valued Senior Member

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    Take it easy old son....Have a disprin and a good lay down.
    My claim re the non linearity of gravity and the subsequent result stands as is.
    Your "alternative" approach, and the ego inflated Farsight manner you put your stuff impresses no one, especially me.

    As for your much repeated "quote mining" claims, that's just more dodging of pertinent issues, and the links are all given, so perhaps to support your bullshit, you may like to show how the quote in question was taken out of context.
    Rest assured, when I see the need, pertinent and relevant quotes will continue to be given, along with the whole article concerned for unbiased judgements.
    Maybe if we had less self gratuitous, navel gazing from the likes of you and Farsight, and more practical and to the point scientific thought, you would not appear as so irrelevant.
     
  19. paddoboy Valued Senior Member

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    A thought experiment, once put to me by a GR theorist on another forum, who commanded much respect from all taking part in that forum, in regards to the non linearity of spacetime/gravity was along the lines of thinking about the spatial regions of a normal Schwarzschild BH. Given that gravitational information can't travel from the singularity outwards, how does the hole maintain its gravitational field? Remember that GR is a strictly local field, we can only discuss the gravity at a point two thirds of Rs from the centre in terms of what can be locally communicated there. In that sense, then, the bulk of the curvature of space-time at that point is due to a mass which can't communicate with it at all! Locally there is no mass in that particular space-time which is responsible for the shape there. In fact, it is the nonlinearity of space-time which is holding the curvature and providing the field at this point. I would argue that space-time and the associated gravity can exist in GR without gravitating masses.

    His actual reply on that forum was.....
    "GR is a local theory - and this is why I chose to answer the question this way, because we know a lot about the local workings of GR. You can only tell what's going on here and now by looking at space-times which can naturally communicate with here and now. In terms of the theory, any event can only be described meaningfully in terms of other events in its past light cone.

    The immediate example which springs to mind is the space-time between the singularity and event horizon of a Schwarzschild black hole. We know there is space-time there, there is gravitational curvature. But the mass at the hole's singularity is in the future light cone of all events in this space-time, so it can't communicate with them. The gravitational field will only communicate with any infalling masses, but it would still exist if no mass were infalling. This is an undisputable example of a local space-time which exists without any mass. (And a real, plausible one, Greg).

    Now Thorne, as one of the world's leading relativists, will understand the difference between local and global applications of the theory, and will see my point. As the question was asked by Blacky, the answer I gave is kinda definitive (ie it is a real example which proves the possibility).

    If on the other hand we want to ask whether it is possible to have a global solution with space-time but without mass, this is a different question. I don't really think we should include discussions of the quantum vacuum in the answer because we don't yet understand what that has to do with space-time or gravity. I think GR is still probably the best tool to use to answer that question.

    So let's look at cosmological models. The de Sitter model describes an expanding universe of constant curvature which is homogenous and isotropic because the global density is zero - ie all the mass has been removed from the universe. In this model the universal radius grows exponentially and the hubble constant (which helps define the expansion with time) is related to a non-zero cosmological constant (Lambda). Now it might be possible to equate Lambda with a quantum vacuum energy, but this has not yet been performed and so we're guessing to add that factor.

    Basically what I've done here is give one local example and global example of space-times which can exist without mass. It seems those who disagree with me are largely talking philosophically. I'd like anyone who disagrees with me to show me where my examples are wrong (I think I'd have to have both examples shown to be wrong to be convinced)".
     
  20. paddoboy Valued Senior Member

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  21. Q-reeus Valued Senior Member

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    An absurd uncalled-for comment that more than likely will be an apt directive to yourself in the end.
    Already you are sounding weasily paddoboy. Don't try and subtly shift ground. Non-linearity per se was never in question. Your point-blank claim in #27 again:
    Ignoring the nebulous meaning of 'tiny' there (or, how long is a piece of string again?), you unambiguously claim non-linearity = self-gravitation of g-field.
    Impress you? No, wrong even there. The aim is to demolish you, and that will be done.
    The dodging, beginning with the early tendency to weasel words above quoted, is from you not me. I never claimed or even suggested the quote you gave in #27 from 'Einstein Online' was taken out of context. That's you trying to distort my position. Just read again #34.
    Ignoring the hypocrisy of last sentence above, the first has I see been partially fulfilled with your #36 & #37, employing the trademark boldface as though some kind of argument booster. Funny though, not one word in any of those two quoted passages actually states 'gravity self-gravitates'. And if it were there, it would simply mean such authors did not understand the basic implication of LHS vs RHS of EFE's.

    I'm giving you more time to find material from authorities that do so understand. It would be best if you were to attempt a face-saving of sorts and gracefully admitted to your ignorance and error. Just let me know when you have had enough.
     
  22. tashja Registered Senior Member

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  23. OnlyMe Valued Senior Member

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    Tashja, I believe that was and is an unfair quoted(?) response to the two posts. It does not identify what part of Q-reeus' post Rovelli was agreeing with! Portions of his response to paddoboy were personal attacks, rather than a personal or factual interpretation of GR. If that was the full context of Rovelli's comment, he should have withheld comment altogether.., or you should have just left it out of the discussion.

    We, as those reading and/or participating in the discussion, have no realistic way to ask for a clarification. It is often interesting to see what some of these external sources think about, an out of context post or few posts, but it is also a disservice at times where as in this case there is no clarity as to exactly what part of Q-reesus' post, Rovelli's comment was directed.
     
    Last edited: Dec 11, 2014

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