Problem with Schrodinger's Cat

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

  1. DaveC426913 Valued Senior Member

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    The fact that there is a measuring device in the box means that the device and its cat experience what they experience. One wavefunction experiences a poisoned cat, and one experiences a live cat. But outside the box, it has not been resolved which of these two wavefunctions will still exist once the box is opened.

    If you were the cat, you would not have two experiences: 'alive' and 'poisoned'. You would only experience one of them. It's just that there would be two cats having two experiences.

    It's kind of like peeling an onion.
     
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  5. Dinosaur Rational Skeptic Valued Senior Member

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    The problem in understanding is due to focusing on measurement & observation.

    There seems to be a quantum level of reality and a classical level of reality (The latter is also referred to as the macro level or the world of our senses). It might not be possible to precisely define the boundary between the two levels.

    With the caveat relating to defining the boundary, one should focus when a quantum level process has an effect at the classical level. Quantum phenomena are actualized when they have some effect at the classical level. In many instances, the initial effect is some change in what is called a measuring device. .

    It is a serious mistake to require a conscious observer. It is a serious mistake to require what is normally considered to be a measurment.

    Quantum level entities seem to be lacking certain properties until they have an effect at the classical level. They seem to be able to exist in a limbo state. The cat is a classical level entity. It cannot exist in a limbo state. It is either dead or alive (with a bit of controversy over the dividing line).

    Schrodinger made up his thought experiment as an argument against the Copenhage interpretation of quantum phenomena. The controversy among experts relates to whether or not the thought experiment refutes the Copenhagen experiment.

    I do not think that any expert considers the cat to be in some limbo state neither dead nor alive.
     
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  7. Then in what sense can an object be said to 'exist' if not registered by some kind of measurement/observation? Even if the object itself has a rudimentary awareness of itself that still counts as an observation.
     
  8. Pandaemoni Valued Senior Member

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    For some reason, I can't open the pdf version of this file, but the cached html is available.

    Is the Moon still there when no one is looking at it?

    The answer is "No one *really* knows," though we all have our intuitions.

    Edit: Better link to a more extensive answer Link Though the "answer" it suggests, that the Copenhagen Interpretation is wrong, is a purely philosophical and not at all a scientific answer.
     
    Last edited: Jul 27, 2007
  9. Stryder Keeper of "good" ideas. Valued Senior Member

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    Well you could fly through the moon with your eyes shut, but I wouldn't try it.
     
  10. Pandaemoni Valued Senior Member

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    Obviously, "looking at it" is a tongue-in-cheeck way of saying "measuring it." Firing myself into the Moon, even with my eyes shut, would count as a measurement, and then all agree the Moon would exist for that one instant when it killed me. Once dead, though, the Moon would again potentially cease to exist until the next measurement.
     
  11. Enmos Staff Member

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    If this is true the universe itself doesnt exist. Noone can objectively measure it.
     
  12. GhostofMaxwell. Banned Banned

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    Yes hitting a waveparticle would count as observation, but did you get this "the moon has a probability of not being there if you crash into it" from the king James 2nd psarms?
     
  13. Pandaemoni Valued Senior Member

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    If you crash into it the Moon will definitely be there (by definition). The question is whether the Moon is there when no one is observing it, based on Einstein's query to Abraham Pais ("Do you really believe the moon is not there when you are not looking at it?").

    I do agree that it is a metaphysical question, as there is no science that says that the Moon is or is not there when it's not being measured. There is no science that, at present, can prove that "classical" objects don't behave the same way that "quantum mechanical" objects do. All that can be said is that, if you decide to look at the Moon, the odds are almost exactly, but not entirely, 100% that it will be there. So far as we know scientifically there is an unimaginably tiny, but real, probability that the Moon will "teleport" its way into a different spot in its orbit (or out of its regular orbit entirely). Luckily, the odds are so small that we can reasonably expect that will never happen even if the universe persists for another trillion years.
     
  14. Pandaemoni Valued Senior Member

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    By saying "doesn't exist" what Einstein meant was "exists in a superposition of various mutually exclusive states" (and one of those states would be, for example "the Moon twice as far away from the Earth as it was yesterday" hence the Moon is "not there" in that sense if that unbelievable remote possibility is the one that comes to exist when its wave function collapses).

    In a sense, it's like asking whether an unmeasured electron exists. You get the same answer...which is that we can precisely calculate the odds that it will be there is we try to measure it, but we have no way to say "what it's doing" when we're not performing the measurement. Bohr would say that that question itself was meaningless.

    In that sense, we have no idea what the universe is doing when we are not measuring it, but we can say that if we were to try to measure it, the odds are nearly 100% that it will be there then.

    Until science comes up with a way to test and distinguish the objective and non-objective interpretations of quantum mechanics, all we can do is philosophize.
     
  15. Yorda Registered Senior Member

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    you find the solution to this problem "in your dreams". do the same experiment in a dream and what the dream tells you is that when you're not observing, there is no cat at all. that's why the perfect logic of small children tells that nobody will see them if they close their eyes.
     
  16. GhostofMaxwell. Banned Banned

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    That just sums up the ridiculousness of the suggestions made by people who dont understand the difficult grasp of quantum mechanics.
     
  17. Chatha big brown was screwed up Registered Senior Member

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    This topic has been discussed to death
     
  18. Yorda Registered Senior Member

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    it's not scientific to say that the moon exists when you're not observing it because it's unprovable.

    if you want to understand reality compare it with fiction. the fiction called reality works like all other type of fiction: movies, dreams, books, computer games...
     

  19. Yes, but you have to remember that the scientific method is based on human perceptions and cognitions so, in effect, the Moon 'exists' as an relationship between human consciousness and some kind of 'potential' external to us that interacts and crystalizes into what we call the Moon, and this applies to 'reality' in general. For example, if human beings had never developed eyes then the Moon as we see it today would have no meaning, and one can extend this idea to conclude that the universe could not exist in its present form in the absence of some kind of conscious agents. Take the old chesnut of does a tree that falls in the forest make a sound if there is no one there to hear it? One could argue that when the tree falls it produces air vibrations however is this what we would call sound? Don't forget that air vibrations have to enter our ears and act upon our eardrums which then send nerve impulses to our brain which then makes an interpretation of the phenomena and experiences 'sound'. None of this can happen when there are no ears about to interact with air vibrations, so althought the POTENTIAL of air vibrations exists to become sound it requires our or some other consciousness to produce sound. This idea applies to all of our senses as well, therefore my view is that what we think of as 'reality' is a participatory process involving sentient beings such as us or some other species and the POTENTIAL of the quantum wavefunction to 'collapses' probability into physical reality.
     
  20. Pete It's not rocket surgery Moderator

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    Now you're philosophizing

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    I think it's axiomatic for practical purposes that our perceptions have some reasonable correlation with an objective reality.

    Pete's proposition - Assume that things are as they seem, until given reason to think otherwise.
     
  21. Enmos Staff Member

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    But you can still observe the effects of the moon without seeing the moon itself.
     
  22. Chatha big brown was screwed up Registered Senior Member

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    I don't know but after reading these arguments again, I have to say its "a lot over nothing". There is no difference between measuring and observing, and there are many phases and descriptions of observing. QM is still an infant study and many facets of it are generally inconcusive. As far as schrodenger's cat, I thin only spontenuity can resolve the matter, i.e the natural progess of things, which is the path with the most natural probability and independent of obervation. Just a thought, I haven't read Quantum is a while.
     
  23. Fungezoid Banned Banned

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    Alternate Worlds

    Has eanyone ever thought of the possibility of ALTERNATE WORLDS? Where worlds split like thread when there could be two possible outcomes? So in the case of the quantum cat, in one world the cat is stone dead, and in another the cat is alive and well. Debunk THAT, now mister.
     

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