Virtual bosons and conservation of energy

  1. I read this on a website called Physics for Idiots

    "If an electron gets near another electron it emits a virtual photon which is absorbed by the second electron and lets it know it need to move away."


    If a virtual photon is absorbed, doesn't than make it real, and so break conservation of energy?

    Thanks, Mark
     
  2. jcsd
  3. TumblingDice

    TumblingDice 463
    Gold Member

    The energy is transferred as momentum, according to wiki:
    More here: en.wikipedia.org/wiki/Force_carrier#Forces_from_the_particle_viewpoint
     
  4. If the energy is transferred as momentum, wouldn't that make the virtual particle real? Meaning, if a virtual particle can exist only within the uncertainty principle, and before it disappears transfers momentum to a real particle, where does that momentum come from?

    I would think this could be a source of unlimited energy, if you could freely transfer momentum from virtual particles to real particles.

    I must be missing something...

    Thanks, Mark
     
  5. the momentum the one particle gets is equal to the momentum the other particle is losing....
     
  6. mfb

    Staff: Mentor

    No. Why should it?
    Momentum is conserved at every interaction point.

    No. Energy and momentum are exactly conserved everywhere.
     
  7. Actually I have related question; why do cosmologists worry about things like Boltzmann brains and so on? Isn't the idea there that "observers" could fluctuate out of the vacuum (given almost infinite time) and so with an infinity of universes or some such we would have to worry about the probability that we could be such observers?

    But how does that make sense? Even granted that the vacuum could fluctuate into such a configuration, as stated above this would only be "allowed" for a completely negligible time interval, no matter how long we are allowed to wait for fluctuations. Am I missing something here?
     
  8. mfb

    Staff: Mentor

    It would be weird to be one. And there is no reason why a Boltzmann brain should have a memory that looks like the world would follow any specific rules - this would be a very rare coincidence.
    Still long enough to wonder about the world. This is very rare, but it could exist.
     
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