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Objects without quantum nature, or without relativistic nature

  1. Sep 20, 2004 #1
    Could there exist entities that either obey only quantum mechanics or obey only general relativity - not as an approximation but as an absolute rule?
     
  2. jcsd
  3. Sep 20, 2004 #2
    The question is a bit surprising. Do you have anything in mind?
     
  4. Sep 20, 2004 #3

    HallsofIvy

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    Relativity applies to all matter and energy and so does quantum physics.

    Quantum "properties" are not, in general, noticeable on the macro scale and relativistic "properties" are not, in general, noticeable at low (relative) speeds- but they are there.
     
  5. Sep 20, 2004 #4
    Gonzolo,

    Perhaps there is a correspondent limit to observation at which the quantum nature of matter ceases. This might be the observable universe horizon, for instance. Likewise, the Planck length might demarcate a lower bound for the relativistic nature of space.

    I suspect that HallsofIvy is right (as far as one can show), but in an infinite universe there can be an infinity of physical systems. The question is where do our familiar rules stop and how can we extend measurement beyond them?
     
  6. Sep 20, 2004 #5
    There is a conflict between Relativity and QM, very basically, QM treats gravity as a force, Relativity treats gravity as a secondary effect caused by the curvature of spacetime. Right now, it doesn't seem possible to extend Relativity down to the quantum level - the mathematics goes nuts. But, by the same token, it currently isn't possible to smoothly merge QM into relativity. This is probably the number one problem in physics today, and is what String Theory, and Loop Quantum Gravity etc are attempting to address.

    As to your second paragraph, I don't think that's exactly true. There are only a finite number of ways that energy and matter can be arranged. And even if it were true, and there were an infinite number of physical systems, the basic assumption of our science is that no matter how many systems there are, they all have to obey the same physical laws.
     
  7. Sep 20, 2004 #6
    geometer,

    If you can, read the article by Max Tegmark on page 40 of the May 2003 Scientific American, especially about his "Level IV Multiverse." His reasoning seems to allow for physical systems, as negligible as they might be, that contain only QM or only GR.

    I was intrigued to read from you and for the first time together that QM considers gravity as a force, where GR models it as an artifact of spacetime curvature. To this effect I wonder what helpful compromise remains in the second article, "P-Duality General Relativity Inside-Out," on my website, below. There I try to introduce action quantization into the metric tensor radial dependence.
     
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