Virtual photons and long range force carrier

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ftr
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It is often said that the photon is the long range force carrier like the static force between electrons. Lets say we have two electrons galaxy apart, wouldn't the virtual particles have to travel long distances and "virtually" become real.

And isn't the first sentence is wrong anyway since real photons are NOT virtual photons.
 

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  • #2
vanhees71
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I don't know, why many people want to confuse themselves as thinking about the Coulomb field between electrons as "virtual photons". It's much simpler to think about them as what they are, namely fields. The Coulomb force is a quasistatic approximation for particles nearly at rest, meaning moving with speeds much slower than the speed of light.

Of course, you can derive this approximation from perturbative QED. You have to resum the socalled soft-photon ladder-diagrams for the two-body scattering-Feynman diagram. This is important to establish the approximation but doesn't help very much in the intuitive understanding of what's going on.

A very good treatment of this issue is found in

Weinberg, Quantum Theory of Fields I.
 
  • #3
ftr
603
43
I don't know, why many people want to confuse themselves as thinking about the Coulomb field between electrons as "virtual photons". It's much simpler to think about them as what they are, namely fields. The Coulomb force is a quasistatic approximation for particles nearly at rest, meaning moving with speeds much slower than the speed of light.

Of course, you can derive this approximation from perturbative QED. You have to resum the socalled soft-photon ladder-diagrams for the two-body scattering-Feynman diagram. This is important to establish the approximation but doesn't help very much in the intuitive understanding of what's going on.

A very good treatment of this issue is found in

Weinberg, Quantum Theory of Fields I.
Thanks for the reply. of course I know about the math, I have tons of books on QFT. But sometimes the descriptive statements can become annoyingly confusing.
 

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