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Which Quantum Interpretation could make a difference?

  1. Dec 30, 2011 #1
    Is there an interpretation of quantum mechanics, which could make a difference to future calculations and results? Maybe an interpretation which could rewrite and simplify the algebra? Or one which has new testible results which when correct would change the quantum mechanical equations to make them more precise or simpler?

    I mean there are popular interpretations like many world interpretation, but it is hard to see why one should put up a theory like this which is neither more powerful nor more intuitive than a copenhagen interpretation. Also Bohm might be easy to grasp for the human mind, but result-wise it only complicates things?
  2. jcsd
  3. Dec 30, 2011 #2
    If you look at the thought experiment in GianCarlo Ghirardi's book 'Sneaking a Look at God's Cards', one could see if the Copenhagen interpretation holds or not.
  4. Dec 30, 2011 #3
    i think the GRW theory (ad hoc 'collapse' theory, which puts in collapse 'by hand' by adding a nonlinear term to the Sch Eq. ) gives testable results, since in reality no wavefunction collapses instantaneously. (see https://www.physicsforums.com/showthread.php?t=446783)
    But i should warn you, i am no expert.
    From what i understand, TI and PTI Transactional*Interpretation (John Cramer's) do not give new testable predictions.
  5. Dec 30, 2011 #4
    I think many of them claim that they make somewhat different predictions but only under as yet untestable situations. Consider one deBroglie/Bohm interpretation:
    Inflationary Cosmology as a Probe of Primordial Quantum Mechanics

    De Broglie-Bohm Prediction of Quantum Violations for Cosmological Super-Hubble Modes
  6. Dec 30, 2011 #5
    If you are really interested in the subject i just found a great review article on decoherence and interpretations:

    Decoherence, the measurement problem, and interpretations of quantum mechanics
    Rev. Mod. Phys. 76, 1267–1305 (2005)
  7. Dec 30, 2011 #6
    Why would you say that it complicates things result-wise?
  8. Dec 30, 2011 #7
    The thought experiment in the book I mentioned is in regards to standard QM, not his GRW theory.
  9. Dec 30, 2011 #8
    GRW isn't exactly an interpretation of QM. its a completely new theory.
  10. Dec 30, 2011 #9
    ok that is more strictly true since it modifies the SHE. but it also sheds some light on measrument and decoherence treating them as wavfunciton leaking from system with small #dof to a system with large #dof again see the post by zpower
  11. Dec 31, 2011 #10
    Thanks! That's exactly the type of answer I'm looking for :)
    And of course I'll try to understand it myself before I make a judgement.

    Good advice. As I'm really interested, I've already looked for lots of papers and this one is on my list too. I'm afraid the list is too long though, with lots of unneccessary information.

    Because it makes the same predictions at the cost of being non-local (and non-linear?). I have a book about Bohm Mechanics I'm eager to read, however I'm slightly losing interest in this interpretation since it lacks nice properties the Schroedinger equation has.
  12. Dec 31, 2011 #11

    Vanadium 50

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    By definition, all interpretations of the same theory have exactly the same predictions. If the predictions are different, they are different theories. By definition, therefore, interpretations are untestable. If they were testable, they wouldn't be interpretations.

    One area of confusion is that some proponents of some interpretations claim testability. You can't have it both ways - if it makes different predictions, it's not the same as QM, and if it makes the same predictions, how can you tell?
  13. Dec 31, 2011 #12
    Where are you basing this on? The (same) Schrödinger equation still holds true in the De Broglie-Bohm theory, so it's just as linear as orthodox QM. And as for non-locality: this doesn't change any of the math. I've never quite understood what the objections against a non-local physical picture could be if the only alternative is no physical picture at all (okay this statement is perhaps a bit bold, but it's to get an idea across that's worth a thought). It can also be argued that non-locality is inherent in all "versions" of QM; it simply becomes more explicit when you're specifying and underlying physical reality. Anyway, these arguments are not meant to convince you that the Bohmian interpretation is the best, certainly not, but is meant to convince you that those arguments you bring up are irrelevant. (Disclaimer: re-reading my post, my sentences could be read in a harsh tone. This isn't the intention! I think it's good that you're interested in interpretations. Sometimes it's easy to misinterpret someone's "tone" when you can only read what he says. Best of luck!)
  14. Dec 31, 2011 #13
    Different predictions result if the standard interpretation holds in the thought experiment Ghirardi proposes.
  15. Dec 31, 2011 #14
    The Schrödering is local, deterministic, linear and the simplest equation one can imagine. I believe it's a pity to lose this features for the very first idea about reality that came to people's minds. So at some point I'd rather think an alternative interpretation of what the wavefunction means, than squeeze a simple equation into a complicating form.
    But ideas and speculations are not part of this forum, so I'd rather listen to ideas which interpretation or alternative QM could make a difference :)
  16. Dec 31, 2011 #15

    Vanadium 50

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    Then it's a different theory. That's what being a different theory means.
  17. Dec 31, 2011 #16
    .... therefore entails Copenhagen Interpretation isn't a valid interpretation for QM.
  18. Jan 1, 2012 #17
    Regarding the question in the title of the thread, the answer is that no interpretation of QM has made a (quantitatively measurable) difference. So, you're left with the bare bones QM math, and how successfully you're able to apply that (when it becomes apparent that you need to) depends on how fluent you are with it, your ingenuity, the breadth and depth of your knowledge of your subject matter, etc.

    The current status quo, afaik, is that 'interpretational issues' are just so much fluff wrt applied physics.

    If you have a particular question wrt how QM might be applied to something that you're working on, then maybe somebody here can offer some insights.

    Otherwise, I would just direct you to the posts of Vanadium 50 and aimforclarity, the only, afaik, physics phd's who've responded to your question thus far.

    This is not to say that your question isn't a good one. But what you're really asking is, imo, whether current QM can be the basis of a more encompassing and deeper theory of nature. And I suppose, I hope at least, that there are some really smart people working on this pretty much continually. And I also suppose that when/if they come up with something important, then they'll certainly publish it. But, afaik, and imho, no extant interpretations of QM hold the promise of a deeper, more 'realistic', QM.
  19. Jan 1, 2012 #18
    When you think about it almost any theory can be made to have many different interpretations but then one has to add so many corollaries to it that it's dismissed on principles of simplicity/elegance, etc. Think about relativity. There are really 3 different interpretations:
    Physicists chose one over the other for reasons of simplicity/elegance, I think? With QM, it's harder because all interpretations are equally hard to swallow, or so it seems.

  20. Jan 1, 2012 #19
    I don't quite get what you're getting at. Are you under the impression that de Broglie-Bohm changes the Schrödinger equation?
  21. Jan 1, 2012 #20
    I don't think that all QM interpretations are equally hard to swallow -- just the one's that entail a metaphysical picture that seems to contradict our experience ... such as MWI or dBB. The Copenhagen interpretation is essentially an instrumentalist one. And, afaik, it's the CI, combined with the Born/probabilistic interpretation that most working physicists think in terms of when applying QM. In other words, there's no way to know, qualitatively, the reality underlying instrumental behavior -- so, when you've got real problems to solve you just accept the simplest, most straightforward, interpretations of the QM math, which seem to be the CI (in its simplest, instrumentalist form) along with the Born/probabilistic interpretation(s).

    The hard thing to get away from is the idea that QM, in its current form, is a description of the real physical reality, of nature. People (most everybody I would suppose) who use the Minkowskian interpretation of SR have the same problem. What I was taught, and what I try to keep in mind, is that these 'interpretations', any 'interpretations', of physical theories are not to be taken as descriptions of 'reality'.
    Last edited: Jan 1, 2012
  22. Jan 1, 2012 #21
    An instrumental approach is also a metaphysical perspective. Most physicists who espouse these models aren't doing so from a "naive realist" perspective but from a "scientific realist" perspective and there's a difference. If physical theories aren't trying to model/describe some aspect of "reality" what are they all about? And what is it that makes us change/update our models as science/physics progress?
  23. Jan 1, 2012 #22
    What physical theories are unarguably and unambiguously about is the behavior of instruments. Mathematical models might reflect a certain 'vision' of the underlying reality, or they might not. Consider the Heisenberg 'picture'. Does that give you a visualizable apprehension of an underlying reality?

    What makes physicists change/update their models is the behavior of instruments. Nobody knows what's happening in the reality underlying that behavior. But inferences/guesses regarding the underlying reality are made, based on the instrumental behavior and our sensory experience.
  24. Jan 1, 2012 #23
    You are absolutely right. In fact I don't have a particular problem, but I rather want explore ways to interpret the way function a better way. I want to understand why guessing the Schrödinger equation works and what is the bare minimum to set up QM. One key question would be why <x|p>=exp(ikx)
    Anyway... :)

    It's only about notation. Schrödinger is simple and Bohm twisted and it hides the underlying features.
  25. Jan 1, 2012 #24


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    True, but an interpretation can suggest a new approach to fundamental physics, e.g., Relational Blockworld.
  26. Jan 1, 2012 #25
    Most scientific or ontic structural realists don't claim that our models are duplicate copies of mind-independent reality, only that they are guided by that reality. The theoretical abstractions of the physicist cannot be just the result of induction from sense data. There is genuinely creative, theoretical work that is done that go way beyond the instruments or our observations as they involve lawful generalizations and reliable predictions that are applicable way beyond our instruments. The data and observations are useful and have an instrumental character but they are of no particular interest in themselves, "but only insofar as they constitute evidence that permits one to determine fundamental features of the real world" (at least, within our cognitive limitations). Of course, the question which divides philosophers is: "what is the nature of this 'non-empirical element'? Does it belong to the real world or is it a product of our minds? I'm not sure? But I can't see how one can have genuine progress in science if there wasn't some match between the two. Why the match or at least partial match? I have no clue.
    Last edited: Jan 1, 2012
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