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Thread: Quantum uncertainty, and Schrodinger's cat

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    Quantum uncertainty, and Schrodinger's cat

    According to the famous thought experiment, Schrodinger's Cat exists in a quantum uncertain state until the box is opened, and can thus be both alive and dead.

    I've run into someone who insists that this is a logical contradiction, and thus that not only the cat, but quantum uncertainty itself, is impossible.

    Does anyone have a good reference that explains this in a fair amount of detail? Not too technical, since I don't know how much science they really understand.

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    Contributor skepticalbip's Avatar
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    A good place to start would seem to be googling "Copenhagen interpretation". Although Schrodinger disagreed with this interpretation and introduced his thought experiment with the cat in the box to demonstrate how absurd it was, those who supported the Copenhagen interpretation adopted that thought experiment as a real example of their interpretation of quantum uncertainty.... go figure.

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    A cat can either be alive or dead.

    It cannot be both.

    If anybody thinks differently provide the evidence of a cat that is both dead and alive.

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    "Those who are not shocked when they first come across quantum theory cannot possibly have understood it."
    ~ Niels Bohr.

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    Well, it is one interpretation. Another interpretation is the "many-worlds" interpretation, in which the universe splits and becomes two universes, one in which the cat is alive, and another in which it is dead. Win something in the not-so-absurd department, lose a little in the parsimonious department!

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    Quote Originally Posted by skepticalbip View Post
    "Those who are not shocked when they first come across quantum theory cannot possibly have understood it."
    ~ Niels Bohr.
    Whether a cat can be both alive and dead is a matter for biology not physics.

    But all one has to do is produce a cat that is both alive and dead to demonstrate my error.

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    Quote Originally Posted by untermensche View Post
    A cat can either be alive or dead.

    It cannot be both.

    If anybody thinks differently provide the evidence of a cat that is both dead and alive.
    Clearly, you've never been attacked by a horde of zombie cats. It's not really a particularly dangerous attack since they don't so much swarm towards you as they just kind of wander around on their own and ignore you. Zombification doesn't do so much to cats. They are both dead and alive, though.

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    Elder Contributor barbos's Avatar
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    Quote Originally Posted by untermensche View Post
    Quote Originally Posted by skepticalbip View Post
    "Those who are not shocked when they first come across quantum theory cannot possibly have understood it."
    ~ Niels Bohr.
    Whether a cat can be both alive and dead is a matter for biology not physics.

    But all one has to do is produce a cat that is both alive and dead to demonstrate my error.
    Biology is a matter of physics.

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    Quote Originally Posted by untermensche View Post
    Quote Originally Posted by skepticalbip View Post
    "Those who are not shocked when they first come across quantum theory cannot possibly have understood it."
    ~ Niels Bohr.
    Whether a cat can be both alive and dead is a matter for biology not physics.

    But all one has to do is produce a cat that is both alive and dead to demonstrate my error.
    "..the 'paradox' is only a conflict between reality and your feeling of what reality 'ought to be.'"
    ~ Richard Feynman,


    To produce the cat would collapse the wave function so its physical state would be settled. You don't seem to understand (no surprise) what the Copenhagen interpretation is even addressing.
    Last edited by skepticalbip; 03-14-2015 at 05:38 AM.

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    Quote Originally Posted by Togo View Post
    According to the famous thought experiment, Schrodinger's Cat exists in a quantum uncertain state until the box is opened, and can thus be both alive and dead.

    I've run into someone who insists that this is a logical contradiction, and thus that not only the cat, but quantum uncertainty itself, is impossible.
    Logic is secondary to a reality, if reality does not fit your logic then it's your logic at fault, not the reality.

    It only a contradiction when being both alive and dead is not part of his logical system.
    Quantum mechanics has different interpretations but it is mathematically (logically) consistent. It means you can in principle simulate the whole universe on a computer. Of course computer would have to be much bigger than universe but mathematically speaking it can be done. So logic is fine with QM.
    Last edited by barbos; 03-14-2015 at 05:05 AM.

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