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The old problem of the virtual particles

  1. Jul 4, 2010 #1
    Before Posting This , I spent nearly an entire day googling the problem of virtual particles and the conservation of energy , but it only got me more confused :confused:

    Let's review this problem from the beginning :
    Due to Heisenberg's uncertainty relation between time and energy [tex]\Delta t \Delta E \gtrsim \hbar[/tex] , virtual particles are allowed to be created and then annihilated in very very short time . The problem arises from the fact that the creation of the virtual particles violates the law of the conservation of energy : "Energy Cannot be Created or Destroyed"
    some of the solutions of this problem (that I've read during my googling day) is that the virtual particles are some sort of mathematical tools in QFT calculations that doesn't have physical existence , If This is true , What about The Casimir Effect ? didn't it prove the existence of virtual particles ?

    How can this problem be solved ?

    thanks in advance .......
  2. jcsd
  3. Jul 5, 2010 #2
    Virtual particles come from the fact that quantum mechanics is, well, quantum. Like photons are the quanta of EM fields, virtual particles are also field quanta, of things such as the coulomb force and magnetic dipole force. The Casmir Effect is also due to the quantization of the fields.

    This is one of the aspects of QM that 'makes more sense' when particles are thought of in terms of mass/energy quanta, rather than billiard balls.
  4. Jul 5, 2010 #3
    Energy conservation is not violated by virtual particles: Energy does not make sense on short time intervals: it takes time for energy/mass to manifest itself, so in fact nothing is violated.
  5. Jul 5, 2010 #4
    Last edited by a moderator: Apr 25, 2017
  6. Jul 5, 2010 #5


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    I understand (at least I THINK I understand) the concept of virtual particles in QFT, but what I never really understood is what the exact relationship with this concept is with the energy-time uncertainty principle
    \Delta t \Delta E \gtrsim \hbar
    I have the feeling that in QFT you don't need this relation at all to explain virtual particles, right?
  7. Jul 5, 2010 #6


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    Please read an entry in the FAQ thread in the General Physics forum.

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