Free-fall to singularity is BS (or - don't just trust 'authorities')

Discussion in 'Alternative Theories' started by Q-reeus, Oct 23, 2014.

  1. Q-reeus Banned Valued Senior Member

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    Correct.
    Correct.
    The no is correct, although the subsequent reasoning is cloudy but not too far off track overall.
    Well you have me beat Farsight. I was expecting at least one and probably all three answers to be wrong. Based on your para 3) comments in #2 - which on my reading is a contradiction to what's directly implied by your above answers.
     
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  3. Q-reeus Banned Valued Senior Member

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    Well that one scenario is repeated ad nauseum in textbooks, popularizer paperbacks, websites, TV specials, forums etc. As Gospel Truth according to GR. So I wouldn't try and downplay it's significance.
    A claim that imo flies in the face of what I have logically deduced from simply applying, in particular, the supplemented consequences of the last quoted para in #1.
    A rather vague statement as it stands. How exactly does it invalidate my conclusion an infaller at EH is objectively time-frozen wrt distant observers? I have shown the notion, commonly promulgated especially on forum sites, that such time freeze is purely an 'optical illusion', is simply false. The sole 'pure optical illusion' component is due to longitudinal SR Doppler shift - and it's a minor factor compared to the in-principle objectively determinable component(s). [I may have to rethink the exact form of that longitudinal component - my in-the-head-back-of-the-envelope calculation might be slightly off but of no great concern either way.] Could have added to the scenario the fact of Hubble expansion & acceleration, but all that does is slightly complicate, and make even more extreme, the implied simpler case given of treating rest of universe as static. What part of the logic in #1 do you specifically fault?
     
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  5. Farsight

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    Sorry if I've caused any confusion. Even if the neutron is "broken" on the way in, it doesn't catch up with the laser beam. And if the same thing happens to you, obviously you won't be hovering near the event horizon taking measurements.
     
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  7. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    i thought this was comical coming from you, or i mean your mind, where your presentation is coming from.
     
  8. PhysBang Valued Senior Member

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    No, in the context of GR it has a very precise meaning.

    Not at all, as long as you are merely making a limited claim about causal relationships using the reference frame of the distant observers as an approximation.

    So you are not limiting the claim, as GR is constructed, to a claim about the causal relationship between events, or are you limiting the claim, as GR is constructed, to an approximate claim when you are using the system of coordinates of distant observers.
    Your use of an approximate claim about causal relationships as an exact claim about metaphysics.
     
  9. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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  10. paddoboy Valued Senior Member

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    27,534


    The crux of the matter as you and I well know is that it matters not what you think, about GR or me.

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    I'll certainly survive your petty onslaughts, just as GR in its proper format will survive untarnished by your diatribe.

    The following "may" help your outlook on GR.

    """""""""""""""""""""""""""""""""""""""""""""""""""""
    http://www.staff.science.uu.nl/~hooft101/gravitating_misconceptions.html

    Physicists who write research papers, lecture notes and text books on the subject of General Relativity - like me - often receive mails by amateur scientists with remarks and questions. Many of these show a genuine interest in the subject. Their requests for further explanations, as well as their descriptions of deeper thoughts about the subject, are often interesting enough to try to answer them, and sometimes discussions result that are worthwhile. However, there is also a group of people, calling themselves scientists, who claim that our lecture notes, text books and research papers are full of fundamental mistakes, thinking they have made earth shaking discoveries themselves that will upset much of our conventional wisdom. Indeed, it often happens in science that a minority of dissenters try to dispute accepted wisdom. There’s nothing wrong with that; it keeps us sharp, and, very occasionally, accepted wisdom might need modifications. Usually however, the dissenters have it totally wrong, and when the theory in question is Special or General Relativity, this is practically always the case. Fortunately, science needs not defend itself. Wrong papers won’t make it through history, and totally ignoring them suffices. Yet, there are reasons for a sketchy analysis of the mistakes commonly made. They are instructive for students of the subject, and I also want to learn from these mistakes myself, because making errors is only human, and it is important to be able to recognize erroneous thinking from as far away as one can .

    more at....
    http://www.staff.science.uu.nl/~hooft101/gravitating_misconceptions.html
    """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

    http://www.drchristiansalas.org.uk/MathsandPhysics/Relativity/Gravitation.pdf

    http://www.abc.net.au/science/slab/blackholes/story.htm


    Some nice general information in the above links that may help you over your quandary.
     
  11. paddoboy Valued Senior Member

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    Not really....Just enquiring why you have not had your alternative position peer reviewed.
    But in reality, I could accuse you of the same.

    I have no ego to bruise, or any delusions of grandeur to deflate.
    And I'll keep on making comments when and if I see fit, and giving reputable references and links when required.

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    Not at all. Most of my knowledge with regards to cosmology and gravity, aligns with mainstream that has already under gone peer review.
    And all my references are reputable.


    You reject GR. You reject peer review. The logical conclusion for me to reach are [1] that you are someone of note and authority on the subject, or [2] You have delusions of grandeur.
    I have no evidence what-so-ever for number [1]

    Correct.



    I'll leave our forum peers to be the judge of that, just as they will judge the merits of your accusation about derailing.
    The answer is No? So you say.
     
  12. paddoboy Valued Senior Member

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    27,534

    Now now Farsight, you are just telling "porkie pies"

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    [1]What I support is mainstream science in general. I welcome alternative views as long as they can be supported with observational and experimental evidence, and does a better job then the incumbent model and of course, then undergo peer review.
    I have yet to see any alternative hypothesis pusher do that.

    [2]My views are not "convictional" I just ask for the evidence to match the models and claims.
    You have not done that.

    [3]I'm no witchfinder, I just state it as it is. If that in the main aligns with mainstream, that's probably because the mainstream views make the most sense, adheres to the evidence and data more closely, and has already undergone the indispensable proper peer review.

    [4]My honesty on this forum is beyond reproach.
    It's not my fault that you cannot see the usefullness of the "waterfall/spacetime falling in" analogy.
    Analogies all have usefullness Farsight, as you certainly know, being one of their biggest users on this forum, so in deriding it in this case shows a degree of hypocricy.
    Here, check it out again......
    http://jila.colorado.edu/~ajsh/insidebh/waterfall.html

    where in part it says....

    A more insightful way to conceptualize how a black hole works is to picture space as flowing like a waterfall into the black hole. At left is a movie of Boulder Falls that I photographed. Here's the movie with sound.
    Imagine light rays, photons, as fishes swimming fiercely in the current. Outside the horizon, space is falling into the black hole at less than the speed of light (or the speed of fishes), and photon-fishes swimming upstream can make way against the flow. At the horizon, space is falling into the black hole at the speed of light. At the horizon a photon-fish swimming directly upstream will just stay there, swimming like crazy, but not going anywhere, the inward flow of space exactly canceling the fish's motion. Inside the horizon, the space waterfall falls faster than the speed of light, carrying everything with it. However hard it tries to swim upstream, the photon-fish inside the horizon is carried by the flow of space inevitably inward to its ultimate fate.

    In the image at right, the (happy) fish upstream can make way against the current, but the (sad) fish downstream is swept to the bottom of the waterfall. This picture was drawn by my daughter Wild, and provided the cover image for the June 2008 issue of the American Journal of Physics4.

    Doesn't relativity say that nothing can go faster than light? It is true that nothing can travel through space faster than light. However, in general relativity, space itself can do whatever it likes.

    The idea of space moving is one that you may have met before in cosmology (the study of the Universe at large), in the notion that the Universe expands.


    The Schwarzschild waterfall

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    The picture of spacing falling into a black hole has a sound mathematical basis, first discovered in 1921 by the Nobel prize-winner Alvar Gullstrand2, and independently by the French mathematician and politician Paul Painlevé3, who was Prime Minister of France in 1917 and then again in 1925.
    It is not necessary to understand the mathematics, but I do want to emphasize that, because the concept of space falling into a black hole is mathematically correct4, inferences drawn from that concept are correct.

    The Gullstrand-Painlevé metric is

    ds2=−dt2ff+(dr−vdtff)2+r2(dθ2+sin2θdϕ2)
    which is just the Schwarzschild metric expressed in a different coordinate system. The free-fall time tff is the proper time experienced by observers who free-fall radially from zero velocity at infinity. The velocity v in the Gullstrand-Painlevé metric equals the Newtonian escape velocity from a spherical mass M
    v=−2GMr−−−−−√
    with a minus sign because space is falling inward, to smaller radius.
    Physically, the Gullstrand-Painlevé metric describes space falling into the Schwarzschild black hole at the Newtonian escape velocity. Outside the horizon, the infall velocity is less than the speed of light. At the horizon, the velocity equals the speed of light. And inside the horizon, the velocity exceeds the speed of light. Technically, the Gullstrand-Painlevé metric encodes not only a metric, but also a complete orthonormal tetrad, a set of four locally inertial axes at each point of the spacetime. The Gullstrand-Painlevé tetrad free-falls through the coordinates at the Newtonian escape velocity.

    It is an interesting historical fact that the mathematics of black holes was understood long before the physics. Einstein himself misunderstood how black holes work. He thought that the Schwarzschild geometry had a singularity at its horizon, and that the regions inside and outside the horizon constituted two separate spacetimes. I think that even today research into general relativity is too often dominated by abstract mathematical thinking at the expense of conceptual understanding.


    see more at the link.
     
  13. Q-reeus Banned Valued Senior Member

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    Yet another status quo fanboy? With interesting credentials: Confused Idiot University PhD's.
    But maybe that's just a subterfuge - hiding your brilliant mind that fully grasps all intricacies of GR. That roughly the case? Let me put you also on the spot krash661 - provide a detailed point-by-point rebuttal of my #1 - that's the put up. Or learn to shut up. Paddoboy krashed and burned; show us you can do better.
     
  14. Q-reeus Banned Valued Senior Member

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    4,695
    PhysBang, my impression is you are at least trying to be objective and helpful, in contrast to some others here. But above is still vague and amounts to talking in riddles imo. Be specific as to the degree and relevance and precise context of this 'approximation'.

    My claim boils down to something quite simple. Infaller's clock-rate, relative to any and all outside observers (obviously not themselves caught up in BH's), stops at EH - not as an 'optical illusion', but in a purely objective sense. The logical and inescapable conclusion from simply extrapolating (and expanding to include SR component) the observation of that 'gedanken experiment' as per last quoted para in #1. That author, one hopes innocently and subconsciously, simply proceeds to ignore/discount it's clear implications. Things can't get any worse than 'infinitely slow clock-rate' (need I keep repeating - relative to distant observers), yet that is indeed the ludicrous 'logical' implication of further free-fall inside of EH!

    I recall coming across claims that, by working from (inappropriately) extrapolating Schwarzschild metric to interior and 'swapping t and r', that 'things reverse' in such a way that infall to singularity can be considered to happen in finite exterior time. I say that's a bunkum conclusion owing to slavishly applying a mathematical formalism divorced from basic physical considerations. Namely, the gravitational potential which is the determinant of redshift/clock-rate, already negative infinite at EH, 'logically' could only further decline as one hypothetically descends deeper. Some actually believe this makes a shred of sense and the infaller's clock - relative to exterior - in some meaningful sense actually starts ticking again! Rubbish. It's ringing alarm bells, but very few are hearing them. So much easier to trust a consensus-approved Guru's take on it. There is an alternative metric (NOT my own creation) that restores sanity, but I'm not out to plug for it here. Just rub folks noses in the logical mess that Schwarzschild metric leads to.

    Now if you wish to provide a critique that actually tackles the specifics and further provides your own take on what is the 'correct interpretation', please - go for it.
     
  15. Q-reeus Banned Valued Senior Member

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    paddoboy - since I can't persuade you to do the decent thing and quietly slink off, here's my comment on your #27-29. You were forced to admit to your own inability to objectively and meaningfully critique the actually very simple details of my #1. But have this blind trust in 'authorities' - just what my thread title admonished against. So, in keeping with that, here's a suggested way 'to really get at me' vicariously - by proxy. Email 't Hooft or whoever else strikes your fancy. Alert him/them to this thread. Any feedback and subsequent fallout might be interesting. Go for it paddoboy - gain a desperately desired vicarious victory, one demonstrably not possible personally!
     
  16. paddoboy Valued Senior Member

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    tsk tsk tsk.....Telling someone else what to do now?...You are funny.
    Oh, and I'm still fluttering about, keeping an eye on what other provocative take you chose to administer?

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    Calm down ol son!...You'll have a coronary!
    I'm not out for any victory, demonstrably personally or any other way.
    I don't need to.
    You are the one proposing GR scenarios that just are not accepted. Just because I'm no expert on these things, does not mean you have a free reign or are correct.
    You don't have a free reign and you are wrong, according to most professionals and experts that I have read.
    And at this stage, I won't be E-Mailing anyone, although that has been something I have done in the past in certain situations.
    This sitastion here does not warrant it.
    It's done and dusted.
     
  17. Q-reeus Banned Valued Senior Member

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    No, deadly serious. And my challenge was not a command, just a challenge.
    Yes, butterflies and moths are also good at fluttering around, and have similar GR skills.
    Good, in the sense that it logically suggests you have no further motive for continuing our pointless exchanges. I dare not hope too much, but, fingers-crossed.

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  18. Q-reeus Banned Valued Senior Member

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    Oh sh*t - redirected to Alternative Theories! Despite, as I made quite clear to paddoboy in #7:
    Then further on in #13:
    So, nonetheless effectively banished to the wastebasket. Not totally unexpected. I do however expect to be told - here in this thread - who made that decision, on what basis, and exactly when implemented. Is that asking too much?
     
    Last edited: Oct 25, 2014
  19. PhysBang Valued Senior Member

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    It should not be a surprise that there are problems with the Schwarzschild Metric, since the metric, because of its own mathematical nature, cannot be used to describe all of certain spacetime regions. It is a metric that allows one to give an approximate description of the physics of certain events, with certain limitations that, as far as I can tell, have been openly discussed at length in the community of people who study GR.

    It does not seem correct to argue against GR on the basis of the use of an approximation within GR that is known to have specific issues. It is common in studying GR to look at the perihelion advance of Mercury as evidence that GR is correct, but this relies on accepting that Newtonian gravity is an approximation that is not ultimately correct. The use of approximations can't be escaped in science. While it is important to identify when someone is using an approximation in a place where it is not appropriate and when an approximation is not adequate for the purpose it is being tasked, it does not seem to be appropriate to damn an entire theory because of the results of one approximation, especially when others are available.
     
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  20. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    cute

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    .
    it would help if you actually understood anything.
    this is nothing but the typical ramblings of an idiotic individual who is clearly uninformed.
    again, i can not stress enough of how typical your nonsense is.
    some of us actually have careers in this.
    can you say the same ? i doubt it, from your post it appears you have not even taken a higher level of a physics coarse, let alone knowing and understanding anything of relativity,dimension planes[ and possibly esoteric cosmology], high energy physics ,cosmos, and black holes.
    typical,pathetic, relativity denying want to be physicist, nothing more..
    also, how about you shut your pathetic comical mouth running and add some experience to your ramblings.

    http://www.sciforums.com/threads/fr...-trust-authorities.142870/page-2#post-3236871.

    also,
    your incorrect nonsense has been pointed out numerous times.
    just look.
     
    Last edited: Oct 25, 2014
  21. Q-reeus Banned Valued Senior Member

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    4,695
    By that I take it you mean validity only for external metric R>2M, as stated here:
    Within that restriction it's supposed to be exact. And it unambiguously predicts asymptotic time freeze as R -> 2M i.e. EH.
    Other caveats like zero rotation, zero charge, are assumed and 'realistic' deviations from such are not relevant though to the idealized scenario sparking this thread. Some do use interior Schwarzschild solutions for BH, e.g. http://arxiv.org/abs/gr-qc/0609042 , but note the admissions of 'strange' behavior in Conclusions section.
    I don't agree with the approximation argument as some valid excuse given as you know SM is considered exact for given restrictions R>2M, zero rotation, zero charge, vacuum exterior.
    Anyway thanks for being civil and objective which has been an unfortunate rarity here.

    Given the unnotified move to this dumping ground, and considering the dubious opening content of many threads still happily sitting in the Physics & Maths subforum, it's very obvious someone(s) hiding in the shadows have gotten his/their underhanded way. Obviously with the sympathies of at least one Mod/Admin. And faik that could be one-and-the-same. Whatever, I necessarily have to speculate there and it doesn't pay to pursue that. I could well protest it, but this latest strike at me just reminds why I went to lurking previously. Time to resume that methinks. Cheers.
     
  22. Q-reeus Banned Valued Senior Member

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    Amazing levels of invective there - outdoing even paddoboy and about evens with brucep. Leaving out a few others who had more sense this round than to try me. So much for your detailed rebuttal. Scares a little to think that ghastly avatar may be an actual likeness.
     
  23. PhysBang Valued Senior Member

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    Any use of the Schwarzschild metric is an approximation, since it makes assumptions that are not physically likely, but that are assumed to be negligible for certain purposes, as you recognize for many factors. Like any modeling or idealization. It is always an open question as to where this idealization fails because of where effects presumed to be negligible are no longer negligible.

    For whatever reason, you don't want to recognize the mathematical failure of the metric beyond the single point of the singularity. Practicing physicists do not seem to find this approach practical. This seems to indicate that you advocate a different way of doing physics from the way that it is commonly done.
    You are welcome.
     

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