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B Why the "rush" to quantum spookiness

  1. Apr 24, 2016 #1
    Hi, those who have responded to any of my previous posts may remember me as one with little mathematical background beyond college calculus, and only a layman's understanding of physics, though I have read a *lot* of layman-oriented material.
    But I do have a very strong sense that the universe - large & small-scale, ought to be logical and consistent (as biased and unfounded as that sense may be). Nevertheless it seems that that ought to be the default position because it's hard for to imagine that a universe that isn't logical could even exist.

    Enough of that, let me get to the actual question.

    One finds numerous quotes from well-educated quantum physicists and the like to the effect that "the quantum world is just so strange and nobody can really understand it". Because of experimental results that have been obtained: Double-slit experiment, EPR experiments and such.

    But what puzzles me in reading through the course of how modern physics has gotten to this point, is that it seems (perhaps due to my own misunderstanding), that there has been a "strain" of physicists that have been perhaps a little too eager to jump on the bandwagon of "quantum weirdness" as opposed to demanding more logical explanations.

    This thread could get very long, so let me just take one example, EPR. I understand that experiments on Bell's inequality have shown, statistically, that Einstein's being spooked out about action-at-a-distance seems to be wrong.
    Yet, much much before those experiments were ever conducted (~1970s?), there were very strong proponents of the instantaneous connection between entangled particles, as opposed to the hidden variable view of Einstein. Ok, I don't deny that they have been given strong support by those experiments, but my puzzlement is from a slightly different angle. If we use the default position that all interaction should be logical, and the idea of "particles having no interaction between them nevertheless being able to interact" is illogical on the face of it, why is it that any physicist at all argued for the action-at-a-distance interpretation? Why would anyone jump to that conclusion, I guess is what Im asking. Prior to Bell's insight, hidden variables ought to have been a no-brainer, i would think, and any other explanation simply considered to be fringe science, even magic.

    Or was there some other clear reason for holding that view, that Einstein et al. refused to consider (prior to Bell).

    (Incidentally, even in our post-Bell world, all other things being equal, what I would even then tend to conclude is that there is still not spooky action going on, but rather that, for example, maybe there is some underlying, sub-Planck structure to the spatial fabric that allows entangled particles to intercommunicate at some speed that is not instantaneous but merely so many powers greater than luminal speed that it merely appears to be instantaneous -- a structure that we haven't yet been able to discover, but which would make much more logical sense than spooky action. Pure conjecture, to be sure! But not illogical or "weird" :-) )
     
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  3. Apr 25, 2016 #2

    bhobba

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    A lot of research has been done since the early days of QM and much progress has been made.

    These days its not that weird when looked at correctly. It's known to be the simplest generalised probability model that allows continuous transformations between states (which you would reasonably expect of a physical theory ie if it is in a state and one second later in another state then it would have gone though some other state in going there):
    https://arxiv.org/pdf/quant-ph/0101012

    It almost looks like its pulled out of thin air. Not really - the key physical issue is the theory is a theory about observations which occur in a common sense classical world. How does a theory that assumes such a world from the start explain it. A lot of progress has been made but some issues still remain.

    That is he central mystery. Its a problem, but not quite the problem some make it out to be.

    There is no instantaneous spooky action at a distance in QM. Such is a distortion of the facts. What we have is QM allows a different type of correlation than ordinary probability. If you want it to be like ordinary probability with objects having properties regardless of being observed then you need instantaneous communication - but only if you want that.

    Einstein had a certain intuition about he world. His view on QM changed quite a bit over time. At first he thought it wrong. But he eventfully accepted it as correct - but incomplete. He may be right - we simply do not know.

    Thanks
    Bill
     
    Last edited: Apr 25, 2016
  4. Apr 25, 2016 #3
    Thanks for the reply.
    I have to admit I have a very difficult time wrapping my mind around the concept of a "different type of correlation than probability"!
    As i understand, once the state has been established (measured) at one end, the other end automatically knows to be opposite.
    This without interacting (instantaneously or otherwise) across the distance?
     
  5. Apr 25, 2016 #4

    stevendaryl

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    I wouldn't say it's a "rush". People have been puzzling over these things for 80 years or so.
     
  6. Apr 25, 2016 #5
  7. Apr 25, 2016 #6

    DrChinese

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    No one knows really what the mechanism is. There are interpretations which speculate on that.
     
  8. Apr 25, 2016 #7

    bhobba

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    Put a red slip of paper in an envelope and a green one in another. Send one to the other side of the universe. Open one and you automatically know the colour of the other. The systems are correlated - nothing spooky going on. Now it turns out in QM you can do exactly the same thing with particle spins. And you get correlations. Again nothing mysterious. The difference is it has a different kind of statistical
    correlation
    http://www.drchinese.com/Bells_Theorem.htm

    It turns out the reason for that different correlation is that in QM objects do not have properties until measured to have them. But what if we insist? Then we find there must be instantaneous communication. But only if we insist.

    Thanks
    Bill
     
    Last edited: Apr 25, 2016
  9. Apr 25, 2016 #8

    stevendaryl

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    But I would say that the reason nobody finds the colored slips (or coloured, if you like) mysterious is precisely because they assume that it's already red or green before they open the envelope. And that's the kind of explanation that Bell's theorem proves is impossible.
     
  10. Apr 25, 2016 #9
    Anyway the immediate answer to the OP for me is that there's nothing illogical, just weird. There are no situations in which an experimental setup yields contradictory results. Only our assumptions about what's going on before the result may find difficulties.
     
  11. Apr 25, 2016 #10

    DrChinese

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    The key thing was whether you believed QM was complete (as EPR discussed in 1935). Put another way: if you accept that position and momentum cannot both be defined simultaneously, then you have thrown out the meat of the classical viewpoint - and things would be "spooky".

    Honestly, I don't think this question weighed too much on many at the time; because there was just too much going on that QM was doing correctly. It took a while for arguments about the fuller implications of QM to completely take shape.
     
  12. Apr 25, 2016 #11

    A. Neumaier

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    ...and there still is. Even the outcome of Bell-tests is predicted correctly by QM.
     
  13. Apr 25, 2016 #12

    N88

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    BUT are those valid calculations, predictions and their explanations devoid of spookiness?
    Don't some physicists talk of wave-function collapse as if the wave-function is ontic?
    And in your own case ...

    … could we avoid this troubled spooky analogy by recognising that long distance true-love survives due to the correlation that first produced that love? Not to "invisible, arbitrarily stretchable strings of love" but correlation? Thus, when I'm in Paris and my partner visits New York or the moon, it's our unspooky correlation that maintains our lifelong fidelity: until death does us part (say, by one of us crashing into a detector)!
     
  14. Apr 25, 2016 #13

    A. Neumaier

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  15. Apr 25, 2016 #14

    bhobba

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    That QM is spooky is incorrect as I clearly explained.

    The real issue with QM is what I said - ie how does a theory about observations that appear in the world around us explain that world. There are various interpretations with different takes and some issues remain which are fixed by some interpretations and a mystery in others (eg factorisation and why we get any outcomes at all) but we broadly know what's going on and that the early pioneers ideas were flawed (with the exception of Dirac who as always was very wise in sicking to the math):
    http://scitation.aip.org/content/aip/magazine/physicstoday/article/58/11/10.1063/1.2155755 [Broken]
    'Bohr’s version of quantum mechanics was deeply flawed, but not for the reason Einstein thought. The Copenhagen interpretation describes what happens when an observer makes a measurement, but the observer and the act of measurement are themselves treated classically. This is surely wrong: Physicists and their apparatus must be governed by the same quantum mechanical rules that govern everything else in the universe. But these rules are expressed in terms of a wavefunction (or, more precisely, a state vector) that evolves in a perfectly deterministic way. So where do the probabilistic rules of the Copenhagen interpretation come from?
    Considerable progress has been made in recent years toward the resolution of the problem, which I cannot go into here. It is enough to say that neither Bohr nor Einstein had focused on the real problem with quantum mechanics.'

    Thanks
    Bill
     
    Last edited by a moderator: May 7, 2017
  16. Apr 25, 2016 #15
    You and S. Weinberg have no idea how consciousness works. Read, for instance, David Chalmers (about the "Hard Problem"). Ask any neuroscientist if s/he knows how consciousness works: typical answer, "I have nothing to do with that, I study the brain". They know the paucity of answers. There are a few who have a guess, but none agrees with another.

    I can produce contemporary quotes from many authorities in Neuroscience and Consciousness Studies who disagree with you and S. Weinberg - and will, if anyone cares. In fact I have a paper by Weinberg himself which demonstrates this! A good 15% of experts in these fields would expect consciousness to play some special role in physics (for instance, collapsing a wave function); half wouldn't be surprised.

    Admittedly, many would support you and S. Weinberg.

    You and S. Weinberg are wading into a very difficult topic with a pet theory: viz., consciousness is just another physical object obeying the same rules as any other. As PeterDonis says (very justifiably) about pet theories, at least show you've studied the expert's ideas, before proposing your own.
     
  17. Apr 26, 2016 #16

    bhobba

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    Sure - but first you need to show its an issue in QM. Only very fringe interpretations make use of it - its always been fringe but in modern times, for very good reasons, its very fringe. The vast majority assume an objective common-sense world observations appear in, or actually derive that world. Its so fringe, and so likely to degenerate into philosophy the mods, correctly, keep a tight reign on such.

    Thanks
    Bill
     
  18. Apr 26, 2016 #17

    stevendaryl

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    I don't think you have to completely understand consciousness in order to conclude that there is no good reason to believe it is involved in QM at any deep level.
     
  19. Apr 26, 2016 #18

    Mentz114

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    if 'consciousness' is not just another physical object obeying the same rules as any other, then we should not be discussing it in the quantum physics forum.

    As @bhobba has stated, there is nothing wrong with QT that requires such a drastic spooky intervention.
     
  20. Apr 26, 2016 #19
    My position is: consciousness-collapses-wavefunction should be admitted as a perfectly respectable QM ontological interpretation, along with all the others. NOT that the nature of consc should be debated as a physics issue per se.

    bhobba's comment answers Mentz114's. It's not consc per se that matters, rather its role in physics. It becomes an issue (as we all know) in QM interpretations. Does it cause collapse of the wave function? 2 points:

    1) It can't be proven that it does, nor that it doesn't; I think we agree on that? It may be impossible ever to know one way or the other.

    2) I don't know if it does (of course) but maintain it might.

    Suppose for a nanosecond that it does; even, that it can someday be demonstrated. Then clearly that's an important fact for physics: it would provide the correct interpretation of wavefunction "collapse". But it would NOT imply physics "needs to discuss" consciousness beyond this one fact. Au contraire, it would strongly imply physics shouldn't discuss it, since it would have been shown to lie outside its domain.

    Note that physicists do discuss it often. You can't properly formulate MWI without explaining how the consc of the observer "splits" on the multiple paths. MWI has been called "many-minds interpretation" for this reason. (Mind is a synonym for consc). On PF the word comes up often (usually, without degenerating into wackiness). But it's always discussed with the pretense that "we're not really discussing it" - very reminiscent of Victorians discussing pregnancy. This is not the way to get anywhere with a topic.

    Ontology, philosophy in general, are not "part of" physics. Yet they get chewed over ad infinitum! Weinberg, Carroll, Deutsch, ... and going back, Einstein, Bohr, Heisenberg (almost everyone but Dirac) have wasted a lot of physicist-hours over such questions as "Why is there something rather than nothing" etc. I agree - strongly - they shouldn't, but they do. More-or-less the only place you really need to care about the "deep nature of reality" is precisely QM interpretation, where consc may play a leading role.

    Just a couple quotes from Wikipedia, "Von Neumann–Wigner interpretation":

    'The von Neumann–Wigner interpretation, also described as "consciousness causes collapse [of the wave function]", is an interpretation of quantum mechanics in which consciousness is postulated to be necessary for the completion of the process of quantum measurement.'

    'Werner Heisenberg maintained that wave function collapse, "The discontinuous change in the probability function", takes place when the result of a measurement is registered in the mind of an observer.'

    von Neumann, Wigner, Heisenberg weren't "fringe". Other mentioned as holding this view include Fritz London, Rudolf Peierls, Henry Stapp. In first half of 20th century many physicists were comfortable with this interpretation.

    Thus it hasn't "always been fringe". Having said that I admit that some of these people changed their minds later on, and that "in modern times, ... , its very fringe." But not "for very good reasons". If you want to mention one or two "good reasons", go ahead; of course I can effortlessly rebut (just as I'm effortlessly rebutting your current crop of objections). But the discussion would be fruitless: we've all heard it before, have our opinions. Your arguments have absolutely no scientific substance; same with my rebuttals. It's ...
    Common-sense means what laypeople think. And they all feel their mind is something very special, nothing like a chair or some-thing. I can produce quotes from Brian Greene, Daniel Dennett, Albert Einstein, Lucretius, probably every prominent figure who ever said mind was "just another physical object". They say, in effect, "Of course like everyone I can't help feeling the mind is special. But with my scientific knowledge I know it isn't." That clearly shows that, even in their opinion, common-sense says it is special.

    If one had to even slightly understand the phenomenon of consciousness, to do anything at all: one would never do anything at all.

    The "good reason to believe it [might be] involved" in QM is demonstrated by the intense interest, extreme confusion, and lack of conclusion, regarding wavefunction ontology.
     
  21. Apr 26, 2016 #20

    A. Neumaier

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    To make it an interpretation one would need to be able to say something how consciousness achieves the feat of state reduction. Which act of consciousness has the effect? And whose consciuousness? Once one asks questions about the meaning, your proposed interpretations dissolves completely.
     
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