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B Virtual Particles; Making the Universe an Open System?

  1. Sep 28, 2016 #1
    The question here is simple; would the existence of virtual particles make the universe an open system? And if not, why? I thank all who consider this question for their time and would love to hear an answer.
  2. jcsd
  3. Sep 28, 2016 #2


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    We have tons of threads on virtual particles. I suggest a forum search.
  4. Sep 29, 2016 #3


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    Why would it?
  5. Sep 29, 2016 #4


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    To the OP: What is your definition of an open system?
  6. Sep 30, 2016 #5
    The concept of virtual particles come from the mathematical structure of perturbation theory.
    Even more than that, they come from Feynman diagrams, which is a way to interpret the terms in the perturbation in field theory.

    This poses two points:

    1) Although people interpret some phenomena using this concept there is no fundamental evidence that they really exist. I mean, they are used as tool of interpretation without being connected to any observable directly. Also they would violate energy-momentum relation of special relativity (they are off-shell). One might think that's not a big deal. That's when my second point comes in

    2) This is a problem I see which I would be glad if someone has an answer for it. As they come from Feynman diagrams, which come from perturbation theory how would they make sense in a non-perturbative theory? As far as I know they can't (it even makes sense to me that they never will). As a non-perturbative approach is more general, in fact indispensable when dealing with phenomena other than scattering, they cannot be part of the fundamental concepts of physics.

    Therefore, my answer is no because there is no virtual particles.
    Even if you'd like to consider them (for sake of reasoning), as they are not observable they should put no threat to the closedness of the universe.
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