Understanding Virtual Photons and Their Role in Electron Interactions

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Discussion Overview

The discussion revolves around the concept of virtual photons and their role in electron interactions, particularly in the context of quantum electrodynamics (QED). Participants explore the nature of virtual particles, the implications for electron charge, and the behavior of electromagnetic forces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions when virtual photons are emitted by electrons and whether there is always a cloud of virtual photons surrounding each electron.
  • Another participant explains that virtual particles are part of internal processes and do not emerge as final state particles, clarifying that electrons interact with photons via the electromagnetic force.
  • There is a discussion about the self-energy of the electron and how it relates to the charge of the electron not being a fixed value due to virtual photon clouds and virtual electron-positron pairs.
  • A participant seeks clarification on whether this means the electron does not have a fixed charge of -1.
  • Another participant discusses the coupling constant and how it varies with energy, affecting the strength of interactions between charged particles.
  • A question is raised about whether virtual electrons are responsible for spreading electromagnetic forces.
  • A participant asserts that the photon is the exchanged boson responsible for electromagnetic forces and recommends reading Feynman's QED for further understanding.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the nature of virtual photons and their implications for electron charge. There is no consensus on the specifics of how these concepts interact, and some questions remain unresolved.

Contextual Notes

Participants discuss the complexities of virtual particles and their roles in quantum electrodynamics, highlighting the dependence on energy scales and the nuances of coupling constants. Some assumptions about the nature of charge and interactions are not fully explored.

Who May Find This Useful

This discussion may be useful for individuals interested in quantum physics, particularly those exploring concepts related to particle interactions and quantum electrodynamics.

aj_baj
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Hi,

I'm a newbi when it comes to physics, but i read something last night that made me wonder: I read that an electron can send out "virtual photons" that "goes back" to the electron if it doesn't find anything to interact with, my question is now, when are these photons sent out? Is there always a cloud of "virtual photons" around each electron?
Can someone explain to me, please?


*English aint my native language, so please exuse my errors:redface:*
 
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Don't be alarmed by the term "virtual" a virtual particle is simply part of an internal process and as such never emerges as final state particle (which are the "real" particles). Electrons interact with photons via the electromagnetic force. In the language of modern particle physics each force is transmitted by a "gauge" boson, for electromagnetism this is indeed the photon. The process you described is what is known as the self energy of the electron and corresponds to corrections to the approximation of a free (Dirac) Electron due to the electromagnetic force (QED). So yes, an electron is surrounded by coulds of virtual photons, and these even contain current loops, so that an electron is surrounded by virtual electron positiron pairs aswell. The end result is that the charge on the electron is not a fixed vaule and depends on the energy scale with which we look at it!
 
okey, thank you very much!
So this means an electron hasn't exactly the charge -1 ?
or have i misunderstood you?
 
The change is in the coupling constant, which we write as eQ, Q is different for different particles, i.e -1 for the electron 2/3 for the up quark... What happens is that a quantity e^2/4\pi called alpha changes with energy, so that at very high energies electrons will interact with other charged particles with a different strength to that at much lower energies (for QED the coupling gets stronger with higher energies for the nuclear force QCD the coupling gets weaker which is called asymptotic freedom and explains why we don't see free quarks)
 
Is it the virtual electrons that "spread" the electro-magnetic forses?
 
No, the photon is the boson which is exchanged by charged particles, from which the EM forces arise, have you read Feynmans QED? I think you'd enjoy it!
 
Okey, I understand. No, I havn't, were can I find it?
 

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