Classical physics vs quantum physics

  1. Why do we say that classical physics is a lot different from quantum physics?

    The laws that determine the macroscopic world should be derivable from quantum laws. So in a way the Newtonian or classical laws are basically quantum laws( maybe a bit approximated)
    So why differentiate between macroscopic and microscopic world?
     
  2. jcsd
  3. Simon Bridge

    Simon Bridge 15,004
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    We don't (except by mistake). We say that quantum physics is different from classical physics :)

    All dogs may be animals but not all animals are dogs.
    All classical physics is a consequence of quantum - but not all quantum physics can be described classically.

    Technically - classical physics is what QM does on average ... so the math is different.
     
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