Feynman diagrams - electrical charges

In summary, virtual photons are just terms in perturbation expansion. When 2 electrons meet, there is definitely something happening in the electromagnetic field between them, but the repulsive force is not caused by physical emission of photons.
  • #1
Camille
20
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I have a request for some explanation in Feynman diagram concerning repelling/attraction of electrical charges. I have been told that when two charges (say, e1(-) and the e2(-)) repel each other, a photon is being emitted from one of them, and the other charge is later being hit by this photon. There is some confusion I can see in this explanation.

First: Does the charge e1(-) emit just a beam of photons in the direction of charge e2(-)? If yes, then how is that this photons always hit charge e2(-) and never miss? Charge e2(-) could move before photons hit it.

Second: Or perhaps the charge e1(-) emitts photons constantly, in all directions. If that's so, what is the wavelength of those photons? Can we detect them?

Third: Does the interaction between charges is based purely on conservation of momentum? (I mean: charge e1(-) gives up some energy (mass of photon) and is therefore tilted outwards the system and charge e2(-), hit by the photon, also gets tilted - therefore we see the repelling.)

Fourth: In the system of e1(-) and e2(-), do they both emit photons in each other's direction?
 
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  • #2
For one thing, a negative and a positive charge attract each other, not repel.

Feynman diagrams are just a convenient shorthand for a mathematical expansion. They shouldn't be taken too literally.
 
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  • #3
Fair point, my error :D

But they must have something to do with the reality. Photons must be really emitted, right...?
 
  • #4
Camille said:
But they must have something to do with the reality. Photons must be really emitted, right...?

Virtual photons are not really emitted. They are just terms in perturbation expansion. When 2 electrons meet, there is definitely something happening in the electromagnetic field between them, but the repulsive force is not caused by physical emission of photons.

The virtual photons (Green functions) are just a tool used to solve differential equations.
 
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  • #5
Is it already known in physics what is happening in the electric field between the electrons? And I mean at the subatomic particles level.

Can someone share some materials from where I could learn to use and read Feynman diagrams in a more or less easy way?
 

1. What are Feynman diagrams and how are they used in understanding electrical charges?

Feynman diagrams are a visual representation of mathematical equations that describe the interactions between subatomic particles, including electrical charges. They are used to predict the probability of different types of particle interactions and can also help in understanding the behavior of electrical charges in different scenarios.

2. How do Feynman diagrams depict electrical charges?

Feynman diagrams use lines and vertices to represent particles and their interactions. The lines can be straight or wavy, depending on the type of particle, and can also have arrows to indicate the direction of charge flow. The vertices represent the point of interaction between particles, including the exchange of virtual particles.

3. What do the different types of lines in a Feynman diagram represent for electrical charges?

The straight lines in Feynman diagrams represent particles with mass, such as electrons or protons. The wavy lines represent particles that mediate the interaction between charged particles, such as photons for electromagnetic interactions. The dotted lines represent virtual particles, which are not directly observed but are crucial in understanding the behavior of electrical charges.

4. Can Feynman diagrams be used to predict the behavior of electrical charges in all scenarios?

Feynman diagrams are a powerful tool for understanding the behavior of electrical charges, but they have limitations. They are most accurate for predicting interactions between particles at high energies, such as in particle accelerators. At lower energies, other factors such as environmental influences can also play a role in the behavior of electrical charges.

5. How have Feynman diagrams contributed to our understanding of electrical charges?

Feynman diagrams have been a crucial tool in the development of quantum electrodynamics (QED), which is the theory that describes the behavior of electrical charges. They have helped scientists make predictions and test the accuracy of the theory, leading to a better understanding of the fundamental forces of nature and the behavior of subatomic particles.

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