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View Diary: Schrödinger's Church, or Wait Wait, don't Convert Me! (153 comments)

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  •  It is still a bad analogy. The superposition of (0+ / 0-)

    states is a description of probabilities.  Probabilities only describe the future.  The past is always 100% certain.  For example:  what are the odds of the detroit lions winning the superbowl?  Probably 1,000,000:1.  What are the odds of them winning in 1957?  100%!  Because they already won it, it is in the past!  (That is also why you can only bet on future games.)

    So, in 1956 the odds were maybe 100:1, but in 1958 the odds were 100% because it already happened.  The wave function collapsed (i.e. the probability distribution of 1957 championship winners collapsed) into a discrete data point:  the detroit lions won.

    Any time a future event with a probability of outcomes is evaluated (observed), the probabilities 'collapse' to a single outcome.

     As far as the cat is concerned, if it is truly isolated in a box, it is no more or less real than what might be in any box labelled 'cat', especially if the person who put it in there is not around.  It is simply a probability of the accuracy of the label and the reliability & trustworthiness of the person who says "trust me, there is a cat in there".

    To any wingnut: If you pay my taxes I'll give you a job.

    by ban48 on Sun Feb 17, 2013 at 11:46:14 AM PST

    [ Parent ]

    •  The problem with QM is... (1+ / 0-)
      Recommended by:

      ... a large number of things that we observe in day-to-day life break if we view the system as determinate. Take water for example. If we use the Bohr model of electrons as having a circular but unknown orbit, multiple properties of water do not make sense. However, if you use the model of an electron as a probability field, then its chemistry starts to make sense.

      You can't collapse the probabilities into discrete data point without destroying the molecule. In fact, you can't collapse the probabilities at all because of Heisenberg's Uncertainty Principle.  Precision in the measurement of momentum is reciprocal with precision in the measurement of position.

      It's a theory that's central not only to model chemistry, but most contemporary technology as well.  

      The football team is just as bad of an analogy as the cat, because it's a macroscopic phenomenon and a determiniate outcome is, arguably, an element central to the definition of a "game" like football.  One of the points of Schroedinger's cat, imaginative science fiction aside, is that historical probability and quantum probability are quite different from each other, and our everyday intuitions of how probability works don't apply to QM.  

      •  Is it because the statistics is different or (0+ / 0-)

        because what the statistics describes is different? Using momentum & position: I take a measurement on position and 'collapse its wave function'.  The probability field that was position is now a discrete value (or a very small field).  But now I've destroyed what I did know about momentum: its probability field has ballooned.  The system is still indeterminate.  I can never know both values.  I will always need a mathematics that works on probabilities.

        But, most people are familiar with the concept of contingencies.  I just think that is a better framing than state-superposition: that it is both 'alive and dead', when both have no meaning because what might be a cat in a box is actually neither.

        This might sound like splitting hairs, but the whole 'the cat is both alive and dead until an observer looks at it and collapses the wave function' is to me kindof... meh.  

        Versus: the state of the cat is irrelevant because it is locked away in a box.  Likewise, the momentum of a particle whose position I just measured is irrelevant.

        To any wingnut: If you pay my taxes I'll give you a job.

        by ban48 on Sun Feb 17, 2013 at 03:43:46 PM PST

        [ Parent ]

        •  Another problem ... (0+ / 0-)

          ... is that "alive" and "dead" are probably not discrete states that can be put into superposition. Life and death are very much a matter of "I know it when I see it."

          •  A coin toss is a discrete state: I flip a coin (0+ / 0-)

            but don't look at it.  As long as it is covered I have to treat it as a contingency that it may be heads or tail.  Until I look at it, to me it is "could be heads, could be tails".  Even if someone else looks at it and tells me "it isn't a probability distribution, it is a single value", I still don't know what the value is and have to treat it as heads-tails.

            I think the statistics portion of QM mirrors this, and it doesn't have to be so foreign - most people can understand this, even if they cannot follow the math (which I can't :) ).

            The real difference (to me) is the assumption of underlying determination: most people think a coin toss is ultimately deterministic:  if I had all of the appropriate information about the effort of the toss and the throw angle and the wind etc. etc., I could make a deterministic prediction of how the coin will land - vs. in QM that is never the case.

            (PS - I think determination is over-rated, but that is another thread :) )

            To any wingnut: If you pay my taxes I'll give you a job.

            by ban48 on Mon Feb 18, 2013 at 04:57:07 AM PST

            [ Parent ]

    •  But to answer your original objection... (0+ / 0-)

      We can say that a particle in superposition exists, usually because we can measure other properties of the particles in question. For example, a water molecule has no net charge; therefore, it must have equal numbers of electrons and protons.  

      So in the Schrodinger's Cat thought experiment, we know that the box has a cat because we can measure the box and discover that its mass and charge require a cat inside. One obvious objection is that the SC thought experiment requires that cats be quantized in the same way as particles, which any cat-owner will tell you is absurd.  Otherwise the box might equally be filled with pugs, rabbits, old socks, or a volume of an encyclopedia.  

      Larger objects can be put into indeterminate states, but probably not using the bounds of the SC experiment.

      •  Well, I could weigh the box and know something (0+ / 0-)

        is in it :)

        I guess I just don't get caught up in the not-knowing part:  you don't know what is in the box until you open it, you don't know what is in the particle until you measure it.  You had a probability distribution of what might be in the box (cat, dog, hamster, socks) or what 'in' the particle (quantum-state-wise'), but you don't know until you look.  Statistics-wise it is all the same to me.  What make QM different is that measuring one attribute disturbs (destroys information about) another, so you can never know it all.

        (... But now I'm beginning to think it is better to have a different language.  its kindof tough coming up with an example of how counting cats is not only independant of their color, but may or may not recolor the cats ...)

        To any wingnut: If you pay my taxes I'll give you a job.

        by ban48 on Sun Feb 17, 2013 at 04:56:40 PM PST

        [ Parent ]

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