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Quantum Mechanics Prior To The Big Bang

  1. Oct 25, 2014 #1
    Are we able to apply Quantum Mechanics to a Universe Prior to the Big Bang? Or would such mechanics require an entirely new set of formulas?
     
  2. jcsd
  3. Oct 25, 2014 #2
    Would a universe even exist prior to the Big Bang? (Maybe so in a Many-World's interpretation of QM, but not sure.)
     
  4. Oct 25, 2014 #3

    phinds

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    Since there is no testable theory that posits a time before the big bang, you can pretty much make up whatever answer you like, since it can't be tested. Of course, it isn't physics, but ...
     
  5. Oct 25, 2014 #4

    atyy

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    At present, we don't even know if we can apply quantum mechanics very near the big bang, because our current theory of quantum gravity fails when the spacetime curvature is very high. You can ask in the BTSM forum about the LQC bounce if you like.
     
  6. Oct 25, 2014 #5
    quantum gravity fails when the spacetime curvature is very high

    How does Quantum Gravity fail when spacetime curvature is very high? It sounds to me like a plane that is flying straight up and then stalls.
     
  7. Oct 25, 2014 #6

    atyy

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    The failure is pretty much the same as that of quantum electrodynamics. For quantum gravity and quantum electrodynamics to make sense, as we currently understand them, we need to do something equivalent to putting the theory in a large but finite box, and finely discretizing the theory. We only do experiments at very low energies and long wavelengths compared to the discretization, so the discretization doesn't matter, and the theories make good predictions. However, since the theories are discretized, this means they don't make sense if we probe very finely, ie. if we can probe very high energies or high curvatures.
     
  8. Oct 25, 2014 #7

    bhobba

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  9. Oct 25, 2014 #8

    bhobba

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    Its because of the infinities that plague Quantum Field Theory in general.

    To tame those something called Effective Field Theory is required - at least that's the modern view the great physicist Wilson got a Nobel prize for sorting out - its an outgrowth of trying to understand what is called renormalisation. That paradigm is the best way to view quantum gravity:
    http://arxiv.org/abs/1209.3511

    Thanks
    Bill
     
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