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Does that classical world even exist?

  1. Jan 21, 2014 #1
    I mean many people try to abstract the classical world but isnt it just the accumulation of QM properties that build and break down what appears to be an obvious and intuitive classical world. Does QM outright contradict the classical world or does it explain the base fundamentals of our classical world coherently and is in symphony with it. I hope there is some sort of syncronicity of the two worlds. There are people who outright deny our everyday classical lives and deny the fact that both the classical and quantum both work in symphony but no one knows HOW YET.

    My basic question is does classical reality as we know it exist or is this all fake. My intuition and senses tell me this world is real and I hope it is and please I dont want abstract without proof mental masturbation arguments against a classical reality. I am also aware that it is a matter of perspective.

    BUT DOES THE CLASSICAL WORLD AS WE PERCEIVE IT ACTUALLY EXIST ALONGSIDE QM. There is a reason the world I pervceive is mostly classical and (sometimes) quantum. QM does not contradict the classical am I right?
  2. jcsd
  3. Jan 21, 2014 #2
    The philosophy forum is closed now but you can safely say that the world is much weirder than people assume. Look up the interpretations and see if you can find yours.
  4. Jan 21, 2014 #3


    Staff: Mentor

    It exists, its real, not fake, and emerges from the QM realm. Both Copenhagen, the statistical interpretation, and others to varying degrees, all implicitly make that assumption.

    Exactly how that happens is an area of active research. Much has been resolved, but issues still remain and research is ongoing.

  5. Jan 21, 2014 #4


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    Staff: Mentor

    QM does not contradict the classical world at a macroscopic scale. It does at a microscopic scale, but all that proves is that classical physics doesn't apply at that scale. There's no contradiction because if you average out all the microscopic quantum stuff across an entire macroscopic system, you end up with the classical macroscopic view of that system.

    It's somewhat analogous to the way that if you take a microscopic look at individual gas molecules bouncing around, there's no notion of pressure or temperature; but ##PV=nRT## works just fine if you look at a macroscopic collection of these molecules.
  6. Jan 22, 2014 #5
    how do I edit posts I meant to say does THE classical world even exist
  7. Jan 22, 2014 #6


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    Science Advisor

    Take a look at Landau and Lifshitz. They explicitly state the need for the classical world to exist in order to formulate quantum mechanics. Relevant quotes from Landau and Lifshitz are excerpted in Bell's essay http://www.tau.ac.il/~quantum/Vaidman/IQM/BellAM.pdf. In the Copenhagen/orthodox/shut-up-and-calculate interpretation, one always makes a cut of the universe between classical and quantum realms, and quantum mechanics is a way of calculating probabilities of "classical" or "macroscopic" or "definite" outcomes.

    Other interpretations such as Bohmian mechanics and many-worlds (assuming it works) differ in not having to postulate the classical-quantum cut.
    Last edited: Jan 22, 2014
  8. Jan 22, 2014 #7


    Staff: Mentor

    As you would expect from someone of Landau's stature, he is correct.

    But since Landau wrote that text a lot of research has gone on and how it emerges without having to assume it is much better understood.

    At the level I think the OP is at Omnes book would be a good place to start:

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