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Is the vacuum of space really devoid of 'everything'?

  1. Oct 17, 2006 #1
    First off, I guess a solid definition of a perfect vacuum is needed. I think it is a region of space in which no Hadrons, Baryons, or Fermions exist. Is this correct?

    Secondly, assuming a region of space like this exists, surely this region must be permeated by some form of EM radiation propogating through it, right?

    With these two questions in mind, my main question then becomes... Isn't it impossible to have a region of space that is devoid of both elementary particles and photons?

    OT - If one subscribes to idea of a quantum foam, does this foam necessarily permeate every cubic inch of space, or could there be regions of space where no foam exists?

    Forgive me for the loosely worded questions, I am not conversant enough in QM to articulate them properly. Any suggestions or answers are welcome, ty.
  2. jcsd
  3. Oct 17, 2006 #2
    From the time - energy uncertainty relationship, one can deduce that indeed, there is no such thing as a vacuum. For this would imply delta E = 0 violating the inequality.

    in quantum field theory, which I have not studied so my explanation is not to be considered authoritative, there are virtual particle creation - annihilation processes going on all the time. This is measured experimentally by the Casmir Force. Google this, it's good stuff.
  4. Oct 17, 2006 #3
    Yes, I like your two points ptabor. That makes good sense to me, ty.
  5. Oct 17, 2006 #4


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    Also, if an area of space could be devoid of both matter and energy, it would reach Absolute Zero, which is (theoretically) impossible; forbidden by QFT, HUP, Thermodynamics, and several other laws.
  6. Oct 18, 2006 #5
    Interesting points Lurch. You have inspired another question, if a region of space is devoid of matter, won't it already be at 0K since even if there is radiation present, there will be no matter to be thermally agitated?
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