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Thread: A question regarding quantum interpretations

  1. #1 A question regarding quantum interpretations 
    Forum Freshman Kompi's Avatar
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    I am positing this while at the same time being aware that I am not entirely certain I know what the question I should be asking really is, so I hope you will forgive some meandering and confusion on my part.

    I've been reading The Quantum Universe by Brian Cox and Jeff Forshaw in an attempt at finally coming to some degree of understanding as to what quantum mechanics actually imply and finally worked my way to a point where they've started mentioning the idea of multiple interpretations, notably the Many-worlds interpretation.

    To my understanding, the reason it is brought up is that if we attempt to measure the entirety of a system it is necessary that we look at previous events as well, and the possibility that we must look into both what we observed happened and even possibly what could have happened but didn't to end up with the correct result.

    The problem I'm having is that I'm not quite succeeding at grasping where exactly this kind of interpretation becomes necessary - the closest idea I can picture is essentially the throwing of two six-sided dice where the probability of a certain outcome for each dice is going to be 1/6 no matter what, even though the probability of a certain result including both dice has a separate probability distribution. Since you can view this situation both per dice and with both dice at once (and each one is, to my understanding, equally correct depending on what observations you are making), I'm not seeing where exactly the interpretation issue becomes necessary.

    Of course, I realise that what I am essentially doing is trying to intuitively understand something that - as far as the book is concerned - can not be intuitively understood (only believed to be understood by failing to understand the actual complexity) so I full well expect I might get an answer that basically boils down to "It just is the way it is and it doesn't care whether you get it or not."


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    Quote Originally Posted by Kompi View Post
    I am positing this while at the same time being aware that I am not entirely certain I know what the question I should be asking really is, so I hope you will forgive some meandering and confusion on my part.

    I've been reading The Quantum Universe by Brian Cox and Jeff Forshaw in an attempt at finally coming to some degree of understanding as to what quantum mechanics actually imply and finally worked my way to a point where they've started mentioning the idea of multiple interpretations, notably the Many-worlds interpretation.

    To my understanding, the reason it is brought up is that if we attempt to measure the entirety of a system it is necessary that we look at previous events as well, and the possibility that we must look into both what we observed happened and even possibly what could have happened but didn't to end up with the correct result.

    The problem I'm having is that I'm not quite succeeding at grasping where exactly this kind of interpretation becomes necessary - the closest idea I can picture is essentially the throwing of two six-sided dice where the probability of a certain outcome for each dice is going to be 1/6 no matter what, even though the probability of a certain result including both dice has a separate probability distribution. Since you can view this situation both per dice and with both dice at once (and each one is, to my understanding, equally correct depending on what observations you are making), I'm not seeing where exactly the interpretation issue becomes necessary.

    Of course, I realise that what I am essentially doing is trying to intuitively understand something that - as far as the book is concerned - can not be intuitively understood (only believed to be understood by failing to understand the actual complexity) so I full well expect I might get an answer that basically boils down to "It just is the way it is and it doesn't care whether you get it or not."
    Quantum theory makes specific predictions about experimental outcomes. Those expectations are routinely met when the experiments are run. It is in that important sense that quantum theory is understood.

    We're humans, though, and that means that we never stop asking why. The various interpretations of quantum theory aim to satisfy the "why" questions at some level. Everett's MWI version avoids the seeming arbitrariness of the Copenhagen interpretation's invocation of "wave-function collapse under measurement." Since all interpretations of quantum theory are just that -- interpretations -- there is no set of measurements that can distinguish between them. In short, these various interpretations exist to satisfy a human psychological need. If you want to believe that MWI describes what "really" goes on, be my guest. If you want to believe that the Copenhagen interpretation describes "reality," then be my guest.


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    Hm, so basically interpretations are really just ways of trying to picture what the mathematics and observations say in a way we can sort of envision and are essentially not all that important from a perspective of "this is just how it works, deal with it"?

    Or rather, what interpretation one picks - if any - doesn't actually affect the actual outcome in any meaningful way, it just formulates how one explains what exactly happens to reach that result, under the hood?

    Hm, well I think that clears it up quite a bit, really - thanks!
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    Quote Originally Posted by Kompi View Post
    Hm, so basically interpretations are really just ways of trying to picture what the mathematics and observations say in a way we can sort of envision and are essentially not all that important from a perspective of "this is just how it works, deal with it"?

    Or rather, what interpretation one picks - if any - doesn't actually affect the actual outcome in any meaningful way, it just formulates how one explains what exactly happens to reach that result, under the hood?

    Hm, well I think that clears it up quite a bit, really - thanks!
    Yes, the interpretations all make the same observable predictions, so there is no way to distinguish among them experimentally. For that reason, many -- perhaps most -- practicing physicists more or less ignore the interpretations, and prefer instead to "shut up and calculate," as they describe it.
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    https://www.youtube.com/watch?v=LW6Mq352f0E Watch the whole video. If you are familiar with the experiment and it still doesn't make sense I'll elaborate if you want.
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