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B Schrodinger cat superperposition vs sharp state

  1. Jul 4, 2016 #1
    On the Schrodinger cat, can I simply say, outside the box,the state is in superposition,but inside the box, the state is not. Besides, the experiment is so simple to do, how come no body ever did it ?. Just put an animal you hate or even an inset, and observe the expected (50% -50%) result.

    Another suggestion , instead of doing something bad , simply drop a candid to the hand of a human being inside when the isotope decay , and ask that person his experience when the box is open (what did your watch show when you received the candid, or you never receive a candid?)
    Last edited: Jul 4, 2016
  2. jcsd
  3. Jul 4, 2016 #2

    Paul Colby

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    Gold Member

    Nobody did it because the outcome is certain and understood. Looking at a cat with a wave function half in the grave looks either dead or alive. It's wave function is not an observable and it's "observable" live or dead has only two values.
  4. Jul 4, 2016 #3
    Problem is you cannot isolate the cat etc from the environment. If it were a simple experiment to do, I would have thought some people had done it by now. You have groups across the world who are designing experiments to test for macroscopic superposition, which need careful planning and set-up.
  5. Jul 4, 2016 #4


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    Staff: Mentor

    You cannot. The system is defined by its state, so it can only have one state.

    However, you may be misunderstanding the Schrodinger's cat thought experiment. When Schrodinger proposed his thought experiment in 1935 he was not trying to suggest that the cat might be in a superposition of dead and alive; everyone agreed, then and now, that it would not. Whether we open the box or not, the cat is either dead or alive so opening the box just tells us which - it is no more mysterious than if I toss a coin and then have to look to see how it landed before I know if it's heads-up or tails-up. Schrodinger proposed his thought experiment to show that something was wrong with the then-current understanding of quantum mechanics: it did not explain why the cat would not end up a dead/alive superposition, even though that clearly did not happen.

    It took several more decades to discover the solution: if the math is done correctly the dead/alive superposition won't appear. You can Google for "quantum decoherence" or for a less mathematically daunting explanation read David Lindley's book "Where does the weirdness go".
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