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Schroedinger's cat

  1. Jul 18, 2008 #1
    Hello guys, i'm just new here.I have a question about observers.
    This may be a stupid question , but here it goes.

    We have lets say the Schroedinger's cat tought experiment.
    The main question.If you have a particle in a superposition of states, of wich all pure states have a different effect, like the mechanis in the experiment, wich either triggers or not.
    So, if the cat is the observer, doesn't it collapse the wave functin of the particle, just by observing the effect?
    The first instant, tha cat sees the mechanism, it "decides" that it either kill it or not. So the moment that the cat's state is decided, isn't when we look at it, but rather when the cat looks at it (wich is the fist instant).

    Is my logic wrong?....i just taught about, because i read about multi-word theorys and stuff (on this exp.), and don't think that such complicated theorys are needed in this case.
  2. jcsd
  3. Jul 18, 2008 #2
    To show how quantum superpositions contradict common sense, Schrödinger posited his cat-threatening device, in which the outcome of an atomic-scale quantum event would trigger, say, a gun to fire. If, said Schrödinger, the quantum system was in a superposition of the states that triggered and failed to trigger the gun, then the gun would simultaneously fire and not fire. The cat would be both killed and spared.

    Fortunately, there is a way out of this illogical outcome. Every real system, whether quantum or 'classical' (such as a life-sized cat), is in contact with an external environment -- a messy, noisy collection of atoms whose state can never be perfectly known. This coupling between a quantum system in a superposition and the environment in which it is embedded leads the system to 'collapse' or decay over time into one state or another. This process is known as decoherence.
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