Problem with Schrodinger's Cat

Discussion in 'Physics & Math' started by Journey0820, Jul 7, 2007.

  1. GhostofMaxwell. Banned Banned

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    Oh shit!:roflmao:

    Yes, the contrivance he deems ridiculous but not the principle itself. This is what I mean by chinese whispers.

    Can you see where this backs up your claim that actual quantum principles are ridiclous?:bugeye: It escapes me.
     
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  3. Pandaemoni Valued Senior Member

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    I still say the experiment is not "wrong" for the reasons indicated. All that the OP has shown is that he does not prefer the "consciousness based" version of the Copenhagen interpretation, preferring instead a "measurement based version of it that allows for inanimate measurers.

    Since there is no way to prove the latter interpretation "more correct" than the former, you have left the realm of science. One might as well be arguing over how many angels can dance on the head of a pin. Even though I myself disagree with the "consciousness-based" interpretations when it comes to something as complex as a cat, I realize that even my preferred interpretation (of decoherence) is a philosophical gloss on the science involved rather than a scientific theory in and of itself.

    Feynman once wrote:
    What I think he meant was that, while the math of quantum mechanics is very clear, if you try to muddle things by determining what's "really happening to that cat" you lead yourself down false paths. If you think you know exactly what happens to that cat when you are not looking at it, and you think that your answer is a scientific one and that adherents of quantum mechanics are "wrong", then you are mistaken. All that you can say, scientifically, is that there is X% chance that, if we broke open the box now, the cat will be dead (and a 1-x% chance that it will be alive). Everything else is just untestable speculation. If you assume that the math that gives you your percentages is a literal description of reality when you are not measuring it, then you can get cats in superpositions.

    There are dozens of perfectly valid interpretations, and no one of them can be said to be any more or less correct.
     
    Last edited: Jul 7, 2007
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  5. Oli Heute der Enteteich... Registered Senior Member

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    Then re-read it.
    Schrödinger said the CASE was ridiculous, not the contrivance.
    I.e. the interpretation...

    Not the principles - the interpretation that it needs a conscious mind to cause the collapse.
    (Actually, in keeping with the Feynman quote in the post above, then the principles are ridiculous (in that it's totally counter-intuitive

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    ), but they work so WTF).

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  7. GhostofMaxwell. Banned Banned

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    OK the case was ridiculous, I have no problem with that. He still never calls the principle riduculous.

    So you now agree with me good.
    Yes they certainly are counterintuitive but you are also back to saying they are worthy of ridicule. Hard to understand is not ridiculous
     
  8. temur man of no words Registered Senior Member

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    Actualy your solution is what Bohr said. According to Bohr's interpretation measurement causes collapse, measurement being an interaction with a system that undergoes the classical mechanical laws.
     
  9. madanthonywayne Morning in America Staff Member

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    This sounds like the concept behind the maximum improbability drive from the Hitchhiker's Guide.
     
  10. Enmos Staff Member

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    This is arrogance.. why is it that the cats state solidifies when a HUMAN opens the box..
    You guys really think the universe treats human any different than, say, a rock?
    I mean who or what makes it so that a state becomes definate a soon as an observer observes it. Its actually just silly.
    The QM results cant be what they seem to be. Something has to be flawed. There has to be another explanation for them.
     
  11. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    You are correct. The "other explaination" is essentisally the same as why "entropy always increases," why temperature (one particular thermal distribution with a single parameter) exists, why two thermally connected bodies come to the same temperature. In a word: "probability" but for better understanding see:

    http://www.sciforums.com/showpost.php?p=1422754&postcount=17 & http://www.sciforums.com/showpost.php?p=1422822&postcount=19

    Where I show "Time's arrow" (entrophy always increasing) is not part of physic at all, only a result of atomic collision probabilities.

    In the case of the cat (certainly a system of many atoms) the fate of each is unpredictable, just as how long you will live is unpredictable; but this does not make selling life insurance unprofitable as for both cat and life insurance companies, there are large numbers of individual cases/ atoms.

    "Observation" has nothing to due with any creature "looking," not even an ant is required. Conceptually, every atom of the cat, living or dead, is still in a "mixed state." In fact ever atom of the universe is in a "mixed state."

    When one speaks of "being alive" one is not speaking of a small number of atoms. Even though every atom of the living (or dead) organism is in a "mixed state," impossible to fully know the state that atom will be in after an interaction with other atoms, the statistical average of their interactions will with extremely high probablity fall into a few "gross states."

    In the case of S's cat, living or dead, are the gross states. Initially the cat is in the "live gross state" but as time passes it will transition into the "dead gross state." (Cats are not imortal.) The transions is not instantious, but is nearly complete in 10 or 15 minutes from last heart beat; however some parts, which do not require much oxygen such as the claws, may cling to the "live gross state" for a day or so.

    Humans only enter the picture because they define these "gross states." To take a simple example: If there is a covered box with 100 black and 100 white marbles in it that nearly cover the bottom of the box and you shake it up, and then open the box to discover all 100 white marbles have their "X coordinate" greater than any of the black marbles, most humans would say "that is a rare chance state." In fact that state is no more rare than any other PARTICULAR configuration*, but we humans pick out only a very small subset of all the possible states and call them "rare."

    Sometimes the fact that humans are "defining the gross states" becomes obvious. For example, is S's cat living or dead three minutes after the last heart beat?
    ------------------------
    * Brazil, where I live, has a federal lottery with less than half payout ratio. My wife plays it almost every week ("If I don't play I can't win.")
    You chose 6 of 60 numbers (I think). I played it once in a failed effort to get her not to play. I seleceted the six numbers, 2,3,4,5,6 & 7** and let her see my choice.
    She said: "That is silly - You will never win with those numbers." I of course replied: "I have just as good a chance of winning as you do with your six numbers." Point being that my numbers were in a human defined "rare gross set" and her's were in a human defined "very likely to win" gross set.

    One technical comment on "particular configuration" definition: The swap of black ball 17 with black ball 78 makes a new "particular configuration" as I am using the term. I.e. the marbles are not indistinguishable, for example, differ from perfect sphere, impurities, etc.

    **I avoided 1,2,3,4,5 & 6 as there might be some other insane player and I did not want to split the prize if he and I did win.
     
    Last edited by a moderator: Jul 8, 2007
  12. Oli Heute der Enteteich... Registered Senior Member

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    The interpretation. Read my words.

    ?

    You misunderstand:
    not worthy of ridicule: ridiculous.
    The very idea that things "aren't" until measured is mind-blowingly ridiculous: it's what's so fun about physics.

    The 2nd and 3rd definitions.
    It's absurd (i.e. no intuitive and doesn't fit with "real life").
    It's also extravagantly humorous and extremely "neat".
    I accept (fully) that it happens, but it's so *wow*.
    It's phenomenally cool that things don't exist until we look for them.
     
  13. GhostofMaxwell. Banned Banned

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    :thankyou:
     
  14. Dinosaur Rational Skeptic Valued Senior Member

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    Schrodinger definitely viewed his thought experiment as a rebuke of the Copenhagen interpretation of Quantum theory. He developed his wave function in an attempt to provide a classical basis for QT, and was disappointed in the result.

    I do not think any modern expert views the Cat experiment as confusing or a rebuke to the Copenhagen interpretation. .

    Books & articles on Quantum Theory written for laymen suggest some confusing views not actually held by the experts (I am not an expert, use some judgment in accepting my views).

    The essential characteristic of the measurement of a quantum phenomenon is that the measurement indicates that some quantum entity has had an effect on the macro world.

    The Copenhagen interpretation essentially states that quantum level entities do not have properties until there is some effect on the macro world. Neither a measurement nor an observer is necessary. This is not equivalent to stating that quantum entities do not exist until they have an effect.

    I do not think that anyone claims that a photon does not exist until it has some effect. It is claimed (for example) that its polarization does not exist until it has an effect. There are interesting descriptions of incorrect conclusions resulting from the assumption that certain quantum properties exist prior to their having an effect on the macro world. One such conclusion relates to polarity measurments.


    BTW: Collapse of the wave function is a misleading phrase. It is merely jargon for a more complicated description of what is happening. Consider the following analogy.
    • One can create a table of probabilities associated with throwing dice. When the dice are thrown, one could say: “The probability table collapsed to a four.”
    For dice we say that he threw a four or that when dice are thrown a particular number will occur.

    Similarly, the wave function provides a knowledge of probabilities associated with the possible results of quantum level processes. When some result occurs, it might be better (but not as erudite) to say That happened instead of one of the other possibilities. The collapse phrase implies some mysterious process, but this is a misleading implication.
     
  15. temur man of no words Registered Senior Member

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    That is true, but after a measurement the wave function really collapses into a very thin peak supported at the measurement result. That is, measurement forces quantum system to be in one of the eigenstates of the operator corresponding to the measured dynamical variable.
     
  16. Enmos Staff Member

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    I have also heard this variety:
    A tree falls over the forest and nobody is there to hear it.
    Did it ever make a sound or not ?

    Common sense says it does make a sound, but im eager to hear your thoughts about this in light of Schrödingers Experiment.
     
  17. GhostofMaxwell. Banned Banned

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    Of course a tree falling in the woods makes a sound if nobody is there but a
    tree falling in the woods making a sound if nobody is there is not a quantum priciple Just like the scenario that a person still breaks the speed limit if a cop isn't there to see it isn't a priciple of quantum physics.
     
    Last edited: Jul 13, 2007
  18. Enmos Staff Member

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    So what does that mean for Schrödingers Experiment?
     
  19. GhostofMaxwell. Banned Banned

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    I wasn't aware it was an experiment to test a quantum principle, rather it was a demonstration to explain this principle to the layman.

    I personally think it means that Physicist can perilously forget how stupid the average layman can be.

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  20. Enmos Staff Member

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    I know that but from your answer i deduct that you dont believe the cat is both alive and dead until the box is opened.
     
  21. GhostofMaxwell. Banned Banned

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    I believe Schrodinger's analogy has the cat both dead and alive at the same time for you to picture the quatum world, but only the quatum world has two states open at the same time in reality.
     
  22. Enmos Staff Member

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    Ok, i thought we were still in that mindset (Schrödinger's analogy).
     
  23. Dinosaur Rational Skeptic Valued Senior Member

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    The tree falling in the forest is a silly issue dreamed up hundreds of years ago when philosophers were more naive than modern day thinkers. In particular, they did not understand the physics of sound waves.
    • If you define sound as a perception derived from the sensory system of a living creature, prehaps you can claim that the tree does not make a sound.

    • If you define a sound as compression waves in the air, then the falling tree makes a sound.
    Note that if trees could exist in a vacuum, a falling tree would not make a sound if it existed in a vacuum, although it might be possible to sense ground vibrations due to the impact.

    Temur: After a measurement, the input to the wave function has changed.
    I still claim that collapse of the wave function is jargon meaning something like the following.
    • Prior to a measurement, the wave function describes the probability associatied with each possible measurement not yet made. When a measurement is made, one of the possibilities has become real in some sense of the word real.
    I still claim that the situation is analogous to a table of probabilities associated with dice throws. when the dice are thrown and a gvien total results, one might say that the table has collapsed to the particular possibility that occurred.

    The Quantum Theory jargon is used because the situation is much more subtle than a dice throw (due to the Uncertainty Principle, the measuremanet is never as exact as the reuslt of a dice throw), but the general concept is the same.
     

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