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Types of virtual Particals

  1. Jun 12, 2012 #1
    Virtual particals or not only found spontaneously apearing in a vacuum, but also inside atoms via the strong force. My question is are these virtual particals always considered (as far as we know) the same, or do they come in documented/reasonably theorized variatys.

    Any other examples of where virtual particals have a roll in our universe?
     
  2. jcsd
  3. Jun 12, 2012 #2

    mfb

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    Virtual particles are a method to describe (nearly all) interactions. Therefore, as soon as you have some interaction doing anything, you have virtual particles.
    They are just like regular particles, but can violate the energy/momentum-relation.
     
  4. Jun 12, 2012 #3
    So if I rub up against my wall somehow virtual particals are emmited? Or by 'interactions' do you mean strong/weak force, electromagnatism, and gravity? Can you please elaborate.
     
  5. Jun 14, 2012 #4
    according to quantum field theory, you get virual particlee when a process undergoes, such as an electrons and positrons annhilating eachother to create photons. the virtual particle maintains the energy conservation of the system, but the intermitent step (typically a connecting line in a fynmann diagram) that defines the virtal particle can have pretty much any energy (some like to put relativistic limits on it). but i only took a small intro/survey course to qft, so i could have this wrong.

    i think of them more a a mathematical entity rather than an actual particle, hence the virtual.

    there is a lot in qft that people try to create physical meaning for that they probably shouldnt.
     
  6. Jun 14, 2012 #5
    Virtual particles are an artifact of a particular mathematical model. in the perturbation description of quantum theory these particles are the carriers of the interaction between real particles. They do not obey the usual rules. They can travel faster than c and they do not obey E^2 = pc^2 + (mc^2)^2. Whether they exist or not is a subject of much debate.

    I suggest you read the physics FAQ for a complete discussion.
     
  7. Jun 14, 2012 #6
    Virtual particles are an artifact of a particular mathematical model. in the perturbation description of quantum theory these particles are the carriers of the interaction between real particles. They do not obey the usual rules. They can travel faster than c and they do not obey E^2 = pc^2 + (mc^2)^2. Whether they exist or not is a subject of much debate.

    I suggest you read the physics FAQ for a complete discussion.
     
  8. Jun 15, 2012 #7
    Virtual electron-positron pairs, or the physics model they represent, produce the 27-MHz shift in the 1057-MHz Lamb shift in hydrogen, and very significant measurable energy shifts in muonic and pionic atoms. Whether or not virtual particles exist, they have a measurable effect.
     
  9. Jun 15, 2012 #8

    mfb

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    Emission of virtual particles does not make sense - by definition, virtual particles have to be created and annihilated in the described process.
    In addition, virtual particles are a nice model to describe fundamental interactions, like the attraction between an electron and a proton. In contrast, if you want to describe macroscopic things, it is better to do this classical: with electromagnetic fields and so on.

    "Interactions" in particle physics are the strong and the electroweak interaction (which contains the electromagnetic and the weak interaction in the low-energy limit).
     
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