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B Why don't emission/loss of virtual photons lower a charge's energy?

  1. Jul 8, 2017 #1
    Hello all,

    I came to know that electric(electromagnetic in general) force between charge particles is mediated by photons. At first I just wondered what are photons doing here? I mean till what I know is that photons bundels of energy for em radiation and that they are massless but have momentum given by Einstein energy momentum equation.

    So for the photons I am used to they have energy and momentum. And I started to worry how a photon is mediating the electric interaction(force) between two charge particles.

    Then I searched over the internet and find something called Quantum Field Theory, by a simple careful reading I found that the way charge particles interact with each other is by emitting or exchanging photons.

    Now I have two questions: 1 how can exchange of photons led to attractive force between unlike charges and how can exchange of photons led to repulsion between like charges.

    2. Does a charge always emit photons no matter is it isolated or with other charges. If so won't the charge lose its by continuously emitting photons(as photons have energy and they are coming from charge so they should take charge's energy)?

    Finally I am still more confused when folk says that these types of photons are different and are called virtual photons, which do not follow energy-momentim relation . I still do not know how even not following energy-momentum relation can remove my doubts.

  2. jcsd
  3. Jul 8, 2017 #2


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    Staff: Mentor

    Virtual particles are not real. They have the same "physical existence" as the number 3: they are tools in calculations only. Don't expect things in calculations to behave like physical objects.
    No, it only emits photons (=real photons) if it is accelerated.
  4. Jul 22, 2017 #3
    Ok got it! Thank you :)
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