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Strangeness Nuggets to Strangeness Condensation

  1. Apr 15, 2005 #1

    Chronos

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    Earlier this week, I was reading this paper by Brown [of Brown and Bethe fame].
    http://arxiv.org/abs/nucl-th/0504029
    Title: Relation of Strangeness Nuggets to Strangeness Condensation and the Maximum Mass of Neutron Stars
    Authors: Gerald E. Brown, Chang-Hwan Lee, Mannque Rho

    It expands upon the equation of state that Smolin cites as a pillar of his CNS principle, and looks pretty solid. But reading between the lines, I see a more insidious result [for CNS], our universe favors the formation of neutron stars. I was daydreaming about this and the thought occured to me - when/why do stellar cores collapse? And this thought popped to mind: when the mass density of the iron core exceeds the Chandrasekhar limit.

    Somehow that made sense. It explains things like why neutron star masses cluster right around the Chandrasekhar limit.
     
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  3. Apr 15, 2005 #2

    marcus

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    thanks for posting the link.
    I will check it out.
    I dont think the Chandrasekhar limit (about 1.4 solar) provides any kind of upper bound on the masses of a neutron stars that can form from a very massive star at its life's end. Nor does it an upper bound on the masses of neutron stars that grow by accretion.

    But it is an interesting idea, we would need information on accretion mechanisms: If you could "turn off" the collapse to Black Hole possibility and imagine neutron stars growing without limit by accretion, sort of the way we see black holes grow in reality----accretion disks etc.---then might you not get supermassive neutron stars the way we now have supermassive black holes. Odd thought.

    [strictly speaking have to qualify this by saying that the idea of a neutron star isnt so simple, people reckon they have "quark star" cores----dividing line between one type and the other is not clear. so just take "neutron star" to mean all that kind of thing up to but not including black hole]

    the paper by Brown et al has a relevant bit about accretion:
    "In this Section we briefly touch on astrophysical implications relegating details to a future publication [6]. The important astrophysical consequence of the low maximum NS mass is that the standard scenario for binary neutron star evolution [35] does not result in a double neutron star, but in a black-hole, neutron-star binary. In this scenario, after the first born neutron star is formed, it goes into common envelope evolution with the companion giant as the latter expands in red giant stage. During this common envelope evolution it accretes a substantial amount of matter from the hydrogen envelope of the giant companion, as it removes this envelope. Bethe and Brown [36] estimated this amount to be about 1Msol for a 1.4Msol neutron star, whereas with more accurate calculation [37] found 3/4Msol for this mass neutron star. The accretion is 0.5Msol for a 1.1 - 1.2Msol neutron star. Obviously these will be sent into black holes and the result will be a black-hole, neutron star binary. "

    what Brown et all are talking about is that if collapse to BH wouldnt happen there is an extra accretion possibility of about 1 solar mass to be picked up right away just from the binary companion. Other kinds of accretion would depend on circumstances, like the normal material and other neutron stars encountered, and would thus vary. But this is all based on the unrealistic assumption that collapse is "turned off" whereas we know it occurs.
     
    Last edited: Apr 15, 2005
  4. Apr 15, 2005 #3

    Chronos

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    Agreed, marcus. What I see is the possibility black holes evolve from neutron stars via accretion - and very rarely the direct result of a stellar core collapse. When you look at the mass distribution chart for neutron stars, it is remarkable how it clusters right around the Chandrasekhar limit.
     
  5. Apr 15, 2005 #4

    SpaceTiger

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    With Type II supernovae, one might form neutron stars near 1.4 solar masses if the rest of the envelope is given sufficient kinetic energy to escape the collapsed core. If there is much fallback, however, one either gets a black hole or a more massive neutron star. However, as you said, neutron stars tend to cluster around the Chandrasekhar mass, so this implies one or both of the following:

    1) Neutron stars have a very "soft" equation of state, meaning neutron degeneracy can't support much more than 1.4 solar masses.

    2) There's little or no fallback.

    Most of the people I hear talk about it seem to lean towards #1, but I've never heard people say that #2 isn't possible as well, so you could be right.
     
  6. Apr 15, 2005 #5

    marcus

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    Basically the CNS premise is in line with what is #1 here.

    a roundabout way of rephrasing is that if you could turn off black hole formation, then we would observe neutron (neutron/quark etc) stars of considerably higher masses which would have formed from
    A. fallback in type II Sne
    B. accretion during the binary partner's red giant phase
    C. opportunistic accretion and merger
    .....and so on (I dont know enough to list all the possibilities)

    The CNS idea is that parameters of the standard model have been iterated so that they are optimized for the formation of black holes. In effect, this predicts a "soft equation of state" for neutron stars. Finding even one neutron star whose mass reliably measured more than something like 2.5 or 3 solar would falsify CNS.

    Postdictions as a range of basic constants (as well as a few actual predictions making CNS falsifiable) are discussed in
    http://axiv.org/hep-th/0407213
     
  7. Apr 15, 2005 #6

    SpaceTiger

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    Yeah, I heard about this. It sounds like a cool idea and makes a lot of sense, if you ask me. I question its capability of making predictions in the long term, however.
     
  8. Apr 15, 2005 #7

    marcus

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    I dont understand what you mean by "making predictions in the long term".
    Please repeat it in different words.
    It actually has not so far achieved what I would call a startling success in making any predictions AT ALL (long term or short).
    So far there is mostly this kind of lackluster prediction about a "soft" equation of state of neutron stars leading to some kind of upper bound of what masses will be observed.

    My sense is that other predictions can be derived but not enough work has been done. Smolin discusses other kinds of predictions but he does not derive definite numbers, as I recall.

    Do you mean that you have doubts that CNS will EVER be able to generate a good bunch of testable predictions? I could understand doubting that because the idea has been floating around since maybe 1995 and there still are not a lot of predictions on record.

    well, i'm just curious, so please explain with a few more words what you mean by inadequate predictions in the long term
     
  9. Apr 15, 2005 #8

    SpaceTiger

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    That's pretty much what I mean. I qualified it with "in the long term" because I figured it could probably make some superficial predictions (like the soft equation of state) that would keep people interested in the short term, but nothing that would give rock solid confirmation of the theory. Whenever I think about the anthropic principle, this is the kind of theory I generally use as a mental prototype.
     
  10. Apr 15, 2005 #9

    marcus

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    That is interesting. I think of CNS as the opposite of AP

    CNS offers a mechanism for the constants to converge on certain values,
    and it doesnt have anything to do with Conscious Life, or Me or Us the Anthropoi. Furthermore it is predictive----it UNpredicts massive neutron stars, whose observation would refute CNS.

    AP seems to offer no mechanism and discourage looking for any. The constants just are what the are, and permit our existence.
    AP UNpredicts nothing. Our existence is compatible with any observation we could conceivably make! therefore our existence is not predictive.

    So I see a strong logical contrast.

    When you think about AP and use CNS as a mental prototype, do you think of CNS as a prototype of AP or (as I do) a kind of opposite of AP----a scientifically more meaningful alternative to AP?
     
  11. Apr 15, 2005 #10

    SpaceTiger

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    I agree with you that they don't necessarily go together (the principle and this theory), but this theory provides a basic framework upon which many universes could be created as possible hosts to life. In the absence of a theory like this, that's just an assumption of most anthropic arguments.

    Now I should say that I haven't read the paper explicitly and everything I know is from word-of-mouth (and it may not even be the same theory I'm thinking of), so I might say something about the model that is incorrect. If so, my apologies.


    I wouldn't say that's any more or less predictive than the anthropic principle, really. The anthropic principle predicts things like the necessity for certain fusion chains to create certain elements, but it doesn't predict anything with which you can really feel confident about its ideas.


    Hmm, I don't think I agree here. The UNprediction you're talking about here is one in which it's predicting that something won't be observed (like a massive neutron star). The anthropic principle does just as well, UNpredicting anything that's incompatible with the existence of life.

    This might be inconsistent with the AP if the only universes that can create a lot of black holes are those that cannot create life. There's no reason to assume this should be the case, however.
     
  12. Apr 15, 2005 #11

    marcus

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    but how could we, living, observe something incompatible with the existence of life :smile:

    whatever experiment you can imagine doing, and whatever be the outcome of that experiment, that outcome is compatible with the existence of life. so the AP "predicts" every outcome we can observe of any conceivable experiment. In that sense it predicts nothing.

    another way of saying this is that the AP cannot be falsified by empirical observation (it is mushy enough to accomodate any observation)

    It would probably be better for you to glance at the first 3 or 4 pages of Smolin's paper, easy enough to do (they arent technical or timeconsuming) and superior to my attempted paraphrase. The paper is quite straightforward---explicitly states what version of AP he is critiquing, and so on.

    I hope you do because I would value your response to it! I am glad that you know of CNS by hearsay. Grad students in Astronomy probably would do well to be thinking about CNS now, at least in my opinion. I think both it and LQG have potential for generating questions to be settled by observation.
     
  13. Apr 15, 2005 #12

    Garth

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    One question is what do we actually mean by the "Anthropic principle".

    Taking Stephen Hawking's definition, "The world is as it is because we are" it simply acknowledges that the existence of any type of complex life anywhere in the universe requires some pretty tight constraints on various physical constants and laws. This can then lead onto various sub-divisions of the principle:

    1. The Weak AP - It is a selection effect. There is a multiverse of different universes and we are in this one because we can be in no other.

    2. The Strong AP - There is some as yet unknown physical principle that determines these constants to be within the narrow bands that are propitious for life. If there were a multiverse then every universe would have to be propitious for life as a logical necessity.

    3. The Participatory AP - The existence of 'conscious' observers today affects'/'affected' the outcome of the original quantum wave function so that it had to collapse to produce an 'observable' universe that allowed the existence of 'conscious' observers today. The original 'boot-strap' theory!

    4.The 'Fluke' (coincidence) hypothesis - There is only one observable universe, the AP depends on a statistical argument, you cannot do statistics with a sample of one, therefore all we can say is that the anthropic coincidences are just a fluke, a coincidence, a brute fact; we wouldn't be here if otherwise.

    5. The Design hypothesis - the world is as it is because it has been designed to be so teleologically. If design then perhaps a 'Designer' - God in traditional belief or perhaps scientists in a former universe playing at God by creating a new universe in their lab! (Would this be wise?) But then, who created them - indeed who created 'God'?

    If the AP simply reflects of the existence of these coincidences necessary for our existence then CNS is not the opposite of it, rather it is simply one possibility for one of its options - the Strong AP. The CNS would be the mechanism by which, after enough iterations, every universe would maximise the number of BHs and hence the existence of life. (But isn't it a coincidence that the two should be so linked?!)

    Garth
     
    Last edited: Apr 15, 2005
  14. Apr 15, 2005 #13

    marcus

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    I dont see any evidence for the existence of more than one universe, unless you say that what came before the big bang is a separate universe (even tho causally connected and temporally antecedent) because it may have had slightly different values of some constants.

    the words are a bit slippery because we are unused to thinking of the CNS, but I would say we live in a section of spacetime. somewhat like a branching plumbing fitting, or a car's intake manifold, it has one blackhole intake joint (the big bang) in our past and multiple outgo blackhole joints into different futures. so it is a section of the universe, which comprises many such

    maybe one could call it a branch of spacetime

    but I think you know what I mean even tho the words are problematical.

    Anyway, I'd say pretty much the same as the quote from you, Garth, except maybe I'd say
    'cause all I know about is this one universe. (altho I admit it may have branches, time may fork at black holes and go separate ways etc, but its all one whole----same basic laws throughout but with some parameters allowed to vary)


    the reference to life confuses me, in your post, since i dont see life as part of the logic or having explanatory power

    about life, i see IT as something to be understood and explained,
    it is some opportunistic chemistry that can take advantage of the tuning of the parameters that evolves with BH reproduction, which is great.
    we should study it. but it doesnt explain the paratmeters! thats cart before horse.
     
  15. Apr 15, 2005 #14

    Garth

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    Such study or conscious thought is predicated on the existence of a complex system, that is, a conscious mind. The existence of such a mind is to be explained every bit as much as the existence of stars, galaxies, black holes or anything else in the universe, especially as it could much more easily been otherwise.

    Garth
     
  16. Apr 15, 2005 #15

    SpaceTiger

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    Yes, of course, I see what you're getting at, I was confused by your language. I'll try to take a look at the paper sometime soon.
     
  17. Apr 15, 2005 #16

    marcus

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    I am glad you think so too, Garth!

    The evolution of intelligence, and self-awareness, essentially from mud and pond-slime, is a truly wonderful thing and indeed much deserving of study, even as are stars and galaxies (just as you say!)

    Clearly some survival and reproductive advantages go along with the ability and pre-disposition to think as humans do----at least in some situations and cultural contexts.

    Perhaps you can tell me of some good book on the evolution of intelligence in animals (it should not be limited to one species, there is a type of spider in which the ability to plan and outwit another spider serves to obtain it food: namely the less conscious and foresightfull of the two, and of course there is a major unsolved problem in the phenomenal verbal ability of certain parrots :smile:)

    the fact that something like the brain can evolve from scum, where the CONSTANTS in that scum are determined by something totally unrelated to the scum or the mind----the constants may well have converged on their present values because they promote BH formation----is wonderful and demands explanation from first principles, i.e. from the laws of nature.

    What I find a bit silly is when people turn this around backwards and try to explain the laws of nature (which got here without us!) on the basis of the existence of the mind. To that all I can say is :rolleyes: and I take it you might very well agree.
     
    Last edited: Apr 15, 2005
  18. Apr 15, 2005 #17

    turbo

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    Thank you. The fact that we have evolved out of lifeforms that arose earlier in our universe is flipped in the AP to provide "proof" that our universe is fine-tuned to produce us. Kind of silly. Our entire existence is less than a eyeblink compared to the existence of our Earth, and is impossible to comprehend relative to the ages of our Solar System, Milky Way, or Universe.

    The AP tells us that all the properties of the Universe must be "just so", so that the Universe can host our exhaulted presence for a tiny speck of time. I propose extending the AP to the even more finely-tuned FP. This is the Ferrethropic Principle. My ferret is the absolute epitome of character and chutzpa (plus he's really cute). He would not be here if the Anthropic Principle were not true, AND if I were not here to have raised him. I hate to think about the logical extensions of this theory, though, in light of the fact that he had to exist in order to have gotten ear-mites as a baby. I have little respect for ear-mites, and will firmly resist any extension to the Ear-mitethropic Principle.
     
  19. Apr 15, 2005 #18

    marcus

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    :biggrin:
    I was awestruck, turbo, at the thought that ear-mites might at this moment be observing and speculating about the universe, and thinking that their very presence here explains the value of the cosmological constant

    have to go pick up my wife at her class, the ferret and the ear-mites will give me something pleasant to think about in the rush-hour traffic. thx.
     
  20. Apr 16, 2005 #19

    Chronos

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    I perceive that a soft EoS for neutron stars is exactly what Brown is driving at. And the mass clustering just below the Chandra limit is pretty compelling. This nice paper by Chevalier seems to affirm that notion:
    http://arxiv.org/abs/astro-ph/0409013
    Young core collapse supernova remnants and their supernovae
     
  21. Apr 16, 2005 #20

    marcus

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    Chronos thx for both the Chevalier paper and the one by Brown with which you started the thread!

    Both papers lend interest to CNS because CNS predicts a soft equation of state for neutron stars (as you may have mentioned already)

    I would elaborate on that by saying that physicists do not seem able to predict from first principles how large a neutron star can be before collapsing to BH under its own weight.

    However CNS predicts that this mass limit should be low----i.e. that n-stars shd be "soft" and subject to collapse when they reach only a few solar masses.

    this is a real prediction, not derived from the Standard Model first principles, as I mentioned, and it could be falsified by finding a n-star of say 2.5 or 3 solar, which would show CNS wrong (I am not sure about the actual limit but something like that)

    I just took a quick look at the Chevalier and saw a lot about fallback being so much in a SN that the remnant is not even a neutron star but instead collapses directly to a black hole!
    What this suggests to me is that if one could "turn off" the collapse to BH and give neutron stars a very hard equation of state
    (just to see what masses one would get, statistically)
    then Supernovae would supply us with a lot of massive neutron stars

    if we could turn off BH formation and make n-stars hard, in other words, we would be seeing plenty of n-stars with masses like 3 and 4 solar!

    So this is very good news for CNS, because it says that since we do NOT see lots of massive n-stars (with masses exceeding 3 solar) that really does signify that the EoS is soft

    which is a prediction made by CNS and apparently not arrived at by some alternative route from SM principles

    this is cause for some cheerfulness, so thanks again for the paper. also the paper was real high quality, I thought. kudos to Chevalier whoever he is.
     
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