Quantum statistics of angular momentum

Discussion in 'Physics & Math' started by Bruinthor, Jan 26, 2016.

  1. danshawen Valued Senior Member

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    Thanks for being honest, and I do appreciate it. I got the same impression ("bullocks") out of this:

    https://en.wikipedia.org/wiki/Spin–statistics_theorem

    referenced near the beginning of this thread, starting with the second line of a proof: "The vacuum (meaning "spacetime") is Lorentz-invariant". I take extreme issue with this view. The whole point of relativity is that "space" and spacetime most certainly are NOT "Lortentz invariant". Furthermore, it is the nature of real, physical rotation (in the REAL universe, not some static Minkowski-Euclidean rotated one) which assures that this isn't the case.

    In our real universe, you can't "rotate" anything you want as fast as you want. Galaxies don't. They tend to appear rather static, over the long haul. Fundamental particles, on the other hand, may rotate over all directions (an infinite number in fact) with no passage of time at all. This is the essence of what "the passage of time" actually means at its core (rotation to/from linear propagation modes).

    Which pretty much explained all of the "advances" in theoretical physics / math both of my PhD sons (one in math, one in physics) have also been trying to catch me up on. And without much success, I might add. Now I understand why, even if you don't.
     
    Last edited: Feb 6, 2016
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  3. PhysBang Valued Senior Member

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    Talk about missing the point!

    danshawen, you are saying exactly the opposite of relativity theory.

    So you say, yet you are strangely unable to demonstrate any use in physics anywhere for this claim. Whereas every contemporary cosmology textbook has applications for the claim that the vacuum is Lorentz invariant.
     
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  5. exchemist Valued Senior Member

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    But none of all this is relevant to the question about treatment of spin states in Stat TD. Or, if you say it is, please explain how.
     
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  7. danshawen Valued Senior Member

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    Well, for one thing, the ergodic hypothesis was never proven, mainly because it deals with the entropy states of a volume. Birkoff spent most of his life trying to do so.

    Perhaps the reason that "spacetime" cannot be treated as a gas, is because it doesn't behave anything like a gas, thermodynamically, statistically, or otherwise.

    When anyone understands the actual REASON that a fermion behaves like a fermion, and a boson behaves like a boson, then their ideas might actually merit my attention. A few recent and notable attempts at unified field theories failed and failed miserably on this very issue.

    But any volume of spacetime is defined by light travel time r integrated over two relativistic phase angles.. I don't even know what a relativistic gas would look like. Do you? Does anyone? Not like a Euclidean static solid in any dimension, rotating or otherwise I'll be bound. Why is a fermion more like a "solid" than a boson? Don't attribute it to electric charge, because you don't yet understand what that is, either.

    I'm betting, quantum fields and light travel time have more to do with the properties of inertia (both rotational and linear) and with relativity than any more eccentric constructs based on Minkowski spacetime and his Pythagorean complex geometry. Light travel time is only that, in every direction. Three orthogonal dimensions of light travel time if you like; makes no difference. It's only light travel time, not space.

    It isn't that I am out of my depth and won't admit it, because I am, and I do. But you are also out of yours, and won't. That is more than just a little sad.
     
    Last edited: Feb 6, 2016
  8. danshawen Valued Senior Member

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    3,951
    To clarify my last post:

    Anyone here who believes the wikipedia article on spin statistics has proven something by asserting that "space is a Lorentz invariant" is out of their depth.

    Rest mass (or energy) is a Lorentz invariant. The speed of light is the strongest Lorentz invariant. In any given direction, the vector sum of ±c is an invariant, and is the invariant "at rest" state for bound energy (matter) that grants invariance to its linear unbound energy counterpart, the speed of light. In any direction of rotation, ±c propagation for bound energy defines spin = zero, or at rest, and this is also an invariant. 4D intervals are Lorentz invariants ONLY because they contain the speed of light in their expressions. Because of the way they were defined, intervals have no application to the physics of relativity or simultaneity, or anything else. Relativistic space does not support orthogonal vector addition.

    Neither lengths nor wavelengths nor time intervals nor Euclidean geometry nor geometry under rotation are Lorentz invariant. When someone says any of these are invariant, they are negating the power of relativity.
     
  9. arfa brane call me arf Valued Senior Member

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    Bollocks. Spacetime in relativity is Lorentz invariant; if you have a theory and it says otherwise, it's in trouble.

    You go on to mention some of the very quantities preserved by Lorentz transformations:
    . Do you understand why proper time is an invariant?
     
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  10. exchemist Valued Senior Member

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    I admit I have not looked at the Stat TD of spin for many years, but I did cover this at university and I do still understand the concepts even if I've forgotten the maths. The previous discussion about J and Jz is very familiar to me indeed from molecular QM. I fully admit I am not an expert on relativity, but the question in this thread has nothing to do with relativity, even though you seem keen to drag it in.

    The fact is that matter does behave in accordance with the predictions of, for example, Bose-Einstein and Fermi-Dirac statistics, so while you may have misgivings about what spin signifies, to concept works, thermodynamically. I do not believe the questioner in this thread is helped by your speculations which amount to saying, rather like the fabled Irishman, "If I were you, I wouldn't start from here."
     
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  11. danshawen Valued Senior Member

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    Exactly my point.
     
  12. danshawen Valued Senior Member

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    "Preserved by Lorentz transformation" does not mean "invariant". Invariant means "does not change as a function of inertial reference frame". The speed of light is invariant. The amount of rest mass or energy relative to the frame in which it was created is invariant. The state of rest for bound energy defined by +/- c is invariant. Quantum spin (or a lack thereof vectorially) is invariant.

    Yes, I understand what proper time is. Do YOU understand that other than for clocks based on the speed of light, even that concept has no real meaning? Proximity of matter or energy to other forms of matter/energy makes time (proper or otherwise) proceed at different rates, even locally. There is no correction term(s) for that in Minkowski spacetime covariance. That's a shame for a theory which puts so much of its stock in simultanaeity.
     
    Last edited: Feb 7, 2016
  13. exchemist Valued Senior Member

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    ?????

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  14. PhysBang Valued Senior Member

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    So, your point is also that you are not helpful?
     
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  15. PhysBang Valued Senior Member

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    It's like you've never heard of General Relativity.
     
  16. danshawen Valued Senior Member

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    If you are going to Letterfrack (or quantum statistics of angular momentum), it's better to start from somewhere else.

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    And by that I mean:

    No absolute space, geometry, coordinates, or vectors, complex or otherwise, in any number of dimensions other than the exact geometrical centers of fundamental particles, and

    No absolute time, other than the instant (NOT an interval) that is "now" in every entangled frame of reference. Because after that instant, the rate at which time progresses is different everywhere. Except for that instant, simultaneity itself does not exist in this universe. The direction in which time proceeds, in terms of energy propagation and events based on energy transfers is always the same, in all inertial reference frames <c.
     
    Last edited: Feb 7, 2016
  17. exchemist Valued Senior Member

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    No you are better to use current physics. It works perfectly well for such problems. QM and Stat TD are the two pillars on which most of physical chemistry stands, so I do have an interest in this. And they are solid, even though they use the concept of particle "spin". That is all we need in this thread - in fact I rather think that all we need is quantised states associated with magnetic moment, however that arises.

    If you want to speculate about spin and relativity that is fine but it does not add anything to the subject of this thread. You are just derailing it, in my view.
     
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  18. danshawen Valued Senior Member

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    I have a deep and abiding respect for physical chemistry. In college, I met only one student who aspired to that vocation. They had it much tougher than physics or engineering students, and that's saying a lot.

    I'm just beginning to realize what discussions like this one are trying to do with some very incomplete tools. By all means, carry on and I will tune down my outrage.
     
  19. exchemist Valued Senior Member

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    Appreciate it very much, Dan.

    I hope there is not too much need to suppress outrage. I think the thing is that we all need to use models in physics and chemistry that are suitable for the task in hand. Most astronomers doing orbital mechanics can manage perfectly well using Newtonian gravitation and they don't really want to get into a debate about how they should really be using GR to get it absolutely right, except in certain special cases e.g. the precession of the orbit of Mercury. We can do Stat TD perfectly well for most purposes using the idea of QM "spin", and leave to one side the issues about what "spin" really is, in the context of a QM wave-particle.

    It seems to me that to stay sane in science one often needs to invoke the concept of the "Somebody Else's Problem field", as put forward in the Hitchhiker's Guide to the Galaxy series.

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  20. danshawen Valued Senior Member

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    I'm a big fan of Douglas Adams.

    And no one but creationists and ID folks seem to be interested in explaining quantization of redshifts either, and that appears to be a similar problem. When they do explain it, they actually quote scripture for their explanations: expansion of the "curtains of heaven" or some other neo-Ptolemaic nonsense.

    I'm certain it's no conspiracy, but real astrophysicists used to be interested in such stuff. A pity; it could be used to explain so much more. If quantum transitions are going on in the fabric of spacetime (or light travel time) itself, wouldn't it help to know something about how that could happen? It's a quantum process going on with no atomic structure at all that is involved in producing it. Perhaps a clue to what DM or DE is? Oh, no, anything but that. There couldn't possibly be any dynamics between linear and rotational propagation of energy that we don't already know everything there is to know about. Where do you suppose the speed of light itself derives?
     
    Last edited: Feb 7, 2016
  21. PhysBang Valued Senior Member

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    Why would someone want to explain a phenomenon that does not exist? Why do you keep on spamming threads with this redshift quantization stuff when the only link you ever provide on it includes that information that it doesn't really happen?

    Sure, some were interested until better surveys revealed that it didn't happen.

    The only conspiracy here is your own conspiracy of one person.
     
  22. brucep Valued Senior Member

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    This basic scientific principle has been explained to him. Doesn't seem to matter much since it doesn't seem to be what he wants to hear. So the nonsense is neverending. So far. He should be able to understand. Must not want to. It's more fun to 'act a crank' and get a rise out of anybody who respects science scholarship. He must be a masochist. He likes it when people diss him as evidenced by the fact he 'likes' everything said about him. LOL.
     
  23. exchemist Valued Senior Member

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    Please do not introduce yet another red herring.
     

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