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Quantum gravity and Casimir effect

  1. May 21, 2012 #1
    Just a crazy thought, does a massive body actually reduce baseline quantum fluctuations nearby (compared with the outer space which has much more baseline fluctuations), thus mimicking Casimir effect on a much larger scale and draws things towards a region having a reduced quantum fluctuations? Regards Allan
  2. jcsd
  3. May 21, 2012 #2


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    That question cannot be answered:
    1) For all practical purposes, "quantum gravity" must be considered as an hypothesis. There is no experimental evidence, at all, that gravity is in fact quantized. And even if it was, the concrete form of its equations would not be known (and might not be solvable if they were known). Both of those would be required ingredients to answer your question.

    2) There is this crazy notion that the Casimir-Polder force is caused by mysterious vacuum fluctutations. Note that this force is only a quantum-electrodynamical *correction* to the London-dispersion force between neutral atoms/molecules/objects[1] (which is not mysterious at all). This QED effect is in almost all situations completely negligible.

    [1] The title of the original publication even says so: http://prola.aps.org/abstract/PR/v73/i4/p360_1
  4. May 21, 2012 #3
    thanks cgk, can we indirectly check this by comparing the null point energies in relation to gravitational field strengths?
  5. May 21, 2012 #4
    Even though it doesn't change the answer to the question, this point is somewhat misleading in the fact that there is very strong evidence to believe gravity is quantized. Because of Binary Pulsar 1913+16 , it is now accepted that gravitational waves exist. The pulsars radiated energy in a way that was predicted by general relativity, and this was the main factor behind the 1993 Nobel Prize in Physics.

    Gravitational waves have a frequency given by [itex] f = \frac {c} { \lambda} [/itex]. From Planck's law, [itex] E = fh [/itex], we know that a wave with a frequency f has an energy quanta proportional to f by Planck's constant. This energy quanta would, of course, be the quantization of the gravitational field, the graviton.
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