Compression of matter: Limit?

Discussion in 'Physics & Math' started by Dinosaur, May 24, 2018.

  1. Dinosaur Rational Skeptic Valued Senior Member

    From an article in the June 2018 issue of SciAm
    The article includes mentions that Quantum Theory could provide an answer/explanation for the above anomaly.

    The above seems seems weird to me. The location of the volume of space within the Event Horizon seems to be defined. Why should the space-time location of the matter be non-existent?

    If the Black Hole contains X, 10X, or 100X solar masses is there some reason to assume that the volumes are the same, namely a singularity (Id Est: A point)? This notion implies infinite density.

    Why not view the properties of a Black Hole as a mystery to be explained instead of accepting the following notions?

    There is a singularity inside the Event Horizon.

    The space-time location of the singularity ceases to exist.
    Consider the energy output of the sun prior to the development of nuclear physics. It was considered a mystery to be explained, not some weird anomaly.
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  3. billvon Valued Senior Member

    Well but the singularity is not the event horizon. The black hole itself is a point; zero volume. (Alternatively you could argue that since spacetime becomes infinitely 'stretched' its volume is effectively infinite.)
    Because it's no longer observable by _any_ method. If there is no possible way to observe something, and no way for it to affect anything in the universe, it does not exist.

    Well of course it was considered both.
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  5. Confused2 Registered Senior Member

    I suspect black holes are a space-time phenomenon - 'compression of matter' is something of a red herring.
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  7. mathman Valued Senior Member

    Compression to a point is a prediction of general relativity, but it violates quantum theory. Until these theories are unified, all we can say is that e don't know what is happening.
  8. James R Just this guy, you know? Staff Member

    The term "singularity" indicates a problem with the mathematics of the black hole solution to Einstein's field equations of gravitation. What it means is that the general theory of relativity can't tell us what is happening at the centre of a black hole. We need a better theory.

    Of course, GR works fairly well in the limit as the radial distance from the centre goes to zero, up to a point. So we know that matter in the hole moves towards the centre. We know that the density gets larger and larger. What we don't know is where it all goes at the centre (if, indeed, it goes anywhere).

    Black holes are weird. From outside the event horizon, the apparent effects of the mass of the hole are a really due to a kind of "fossilised" gravitational field. From a distance, outside, all the mass that ever fell into the hole looks like it is hovering at the event horizon. Of course, if you were to fall into the hole, things would look different.
  9. Dinosaur Rational Skeptic Valued Senior Member

    From James R Post 5
    The above cannot be the entire story without some further explanation.

    I assume that the missing part of the explanation includes mention that the Event Horizon expands as more mass is added.
  10. RainbowSingularity Valued Senior Member


    i agree with your last sentence.
    what i think they might be alluding to is the mathamatical explanation.
    and... as you say, back around to the start...
    does science know all mathamatics ?
    some say yes, some say no.

    does it make sense using known mathamatics ? = no

    just for arguement sake... i wonder if the nature of the singularity is a force of conveyance so the matter is only able to exist in motion.
  11. Dinosaur Rational Skeptic Valued Senior Member

    A remark from my Post 1
    From Billvon Post 2 relating to my above remark
    The matter in a Black Hole surely can affect some objects due to its gravitational force.

    BTW: Is so called Dark Matter observable? I do not think so: Yet it can have gravitational effects on objects.
  12. RainbowSingularity Valued Senior Member

    i am not well read on this, however, i was under the impresion that gravitational lensing which allows observation of other galaxies shows the ability to measure the difference of the equation that presents the missing value of the required force/energy ... ?
    gravitational lensing being the process to prove gravity effects light ?
    the missing force being the dark energy measured as a missing value of required force etc..
  13. Dinosaur Rational Skeptic Valued Senior Member

    Also from Billvon Post 2
    in response to my Post 1 remark
    A singularity as well as infinite density seems to strongly imply the need for some better explanation.
    RainbowSingularity likes this.
  14. Speakpigeon Valued Senior Member

    Yes, and the crucial point in my view is that from whatever could be observed from outside of the event horizon, it couldn't be said that the matter falling behind is compressed at all. Rather, it would be just a "big sphere" getting bigger as it would absorb more and more matter. So, no problem at all.
    From the point of view of an objective perspective based on observations, this should be good enough.
    While we wait for better.
  15. origin In a democracy you deserve the leaders you elect. Valued Senior Member

    Except for the obvious big problem that this would require and unknown force that is able to overcome gravity and prevent a singularity.
    We had a poster Rajesh (and his sockpuppets) that thought the same type of thing and he was shown that this thinking is not compatible with known science. We could go through that again....
  16. QuarkHead Remedial Math Student Valued Senior Member

    Of course. Look, it is surely not contentious that the relativistic field equations of gravitation do not exclclude the existence of space time singularities.

    Nobody thinks these are "natural" in the obvious sense. The proposed solution (not yet found) is a quantum theory of gravitation, based upon the following weak
    (in my opion) argument:

    a) a space time region of apparently infinite mass-energy density can only be modelled in the same way as the othe three known forces in the Standard Model, because

    b) the other three forces of quantum physics are known to be very short range, and to exceed that of gravitation by several orders of magnitude

    c) therefore (why?) it is assumed that, just as in other sectors of the Standard Model, short range gravitational interactions are mediated by a boson - the graviton.

    I repeat, I do not say this may not be true, merely the argument is weak
  17. Speakpigeon Valued Senior Member

    I don't know that this sweet Rajesh lad had thought "the same type of thing" at all.

    So I will suspect you are just a very, very poor judge of whether two different people had said the same type of thing, let alone had thought the same type of thing.

    Well, I guess I will have to wait for you to prove otherwise. You haven't yet, obviously, quoting what people think being a rather tricky business.

    I'm comforted in my view here by the fact that your first sentence doesn't seem to have any relevance to what I said. This suggests you're just a slipshod reader, whatever the medical reason may be for that.

    Also, you've already responded to a few of my posts in another thread and you did it in a way that suggests to me you're a bit temperamental. Even the tone in your post here is needlessly unpleasant. If you have some bad temper to vent, please go elsewhere to do that.
  18. origin In a democracy you deserve the leaders you elect. Valued Senior Member

    First, writing is used to convey thoughts.
    Secondly, if you don't know what he wrote how do you know I misjudged?

    Uh, it really isn't that tricky. Let me demonstrate; you don't think there's a singularity inside the event horizon. Simple.

    Actually it has everything to do with what you said, perhaps you could re-read the comment and think about it.
    I assume you can not actually determine if someone has a medical condition by reading a few lines in a forum and are just being an asshole.

    We all can't be as sweet as you and Rajesh.
    I think I will decide which posts to respond too.
  19. RainbowSingularity Valued Senior Member

  20. Q-reeus Valued Senior Member

    Above appears to be a pseudo argument of your own making. Only two of the three SM forces/interactions are short range - EM has infinite range just like gravity.
    As far as resolving the infinities inherent in GR's Schwarzschild/Kerr BH's, consider the possibility GR is fundamentally flawed, though sufficiently accurate to have passed muster so far.
    Once again, I refer to Appendix A (also part 2: The Exponential Metric) here:
    Try and spot any 'obvious flaw' there allowing GR to survive unscathed. But given there is no flaw, why continue ruminating over all the baffling conundrums owing to a pathology-generating theory?
    Because it's mainstream and mainstream = Truth? I don't buy that equation.
  21. NotEinstein Valued Senior Member

    In that linked Appendix (assuming it's fully correct) I only see derivations showing that the Schwarzschild metric is bad, or that the equivalence principle can only be true to first order. Where does it conclude that GR is fundamentally flawed, or is that merely your interpretation of it?
  22. Q-reeus Valued Senior Member

    And as any textbook or relevant 'reputable' online article on GR will state, exterior SM is THE UNIQUE solution to EFE's for any spherically symmetric matter distribution. Therefore....
    Wrong read. Correct read - exact derivation of redshift by application of EP via SR is only satisfied in GR to first order (in terms of a series expansion of correct exponential form).
    See above. Further though, given your initial comment '(assuming it's fully correct)' - you also are invited to actually point out any flaw in that appendix A derivation!
  23. Speakpigeon Valued Senior Member

    My assumption is that you're a poor reader and your post here just seems to confirm this. So, sure, writing is most often used to convey thoughts but if you're a poor reader that won't help you much.

    See? You just did it again, right here, confirm you're a poor reader.

    I never said or suggested that I knew you misjudged.

    I couldn't care less about that. That's not what I asked you to do. You really can't read a post apparently.

    I think by now we really have nothing left to talk about.

    Of course not but we all have to go by our impressions and perceptions. I'm sure you do it as well.

    I'm definitely not sweet.

    Good, Let's see how it goes.

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