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Virtual Photon

  1. Nov 24, 2009 #1
    In my lecture this morning i was told that charged particles interact by the exchange of virtual photons and that they serve as carriers of momentum and force. But it says that a photon is a boson with spin number 1, massless and zero charge.

    The question is basically how can a massless particle carry momentum ?
     
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  3. Nov 24, 2009 #2

    dextercioby

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    I would ask you: on what mathematical grounds does a massive particle carry momentum ?
     
  4. Nov 24, 2009 #3
    It is irrelevant if it is virtual or not. Real photons are also masless, but they carry momentum. Massless = no rest mass, you are probably thinking about the 'relativistic' mass.
     
  5. Nov 24, 2009 #4

    George Jones

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    Elaborating a bit on what Dmitry67 wrote, according to special relativity, the energy, momentum, and rest mass of a particle are related by

    [tex]E^2 - \left( cp \right)^2 = \left(m c^2 \right)^2.[/tex]

    For a photon, [itex]m=0[/itex] and [itex]E = cp[/itex].

    Even classical electromagnetic fields carry momentum.
     
  6. Nov 24, 2009 #5

    jtbell

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    And with the same relationship, if you considerf E and p as the energy and momentum densities of the fields.
     
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