Tag Info

New answers tagged

1

Feynman diagrams are more than just the Lagrangian. They can be acquired by expanding the path integral of the theory into a perturbative series. There is a priori no reason to assume that all quantities needed in order to produce sensible results are consistent with gauge invariance. One possible issue is the problem of regularization: the way your ...


0

I assume the first part, up to But how exactly does it happen? defines and explains your question, and then you show what you think about it so far? It looks like the point where it goes wrong is about what the inductor does. There is nothing about "split-second" and relativistic, it behaves in a pretty symmetric way to the capacitor. It's "dynamic" ...


4

Virtual particles are not real It's in the name. You may draw Feynman diagrams where there are internal lines, and we call these internal lines virtual particles. They are not real. You will never detect a virtual particle. They are not really exchanged between the real charged particles. Virtual particles are a just-so stories designed to explain Feynman ...


2

We don't really understand why charge is quantized. Nor we do know if there ought to be magnetic monopoles. These two things seem linked. Dirac gave an argument for charge quantization in the early days, but this presupposed the existence of a magnetic monopole. In Maxwell's equations, it would be completely natural to imagine the existence of magnetic ...


2

Because QED in $D=2$ is a confining theory and as such it develops mass gap. The coulomb potential in $D=2$ is linear with the distance of the charges. It is one of the few exactly solvable confining QFT theories. Perhaps, I should add that by gauge invariance one can always fix $A_x=0$ while for the other component, $A_t$, the equations of motion give ...


1

This is where virtual particles come into play. http://youtu.be/K6i-qE8AigE?t=3m23s Essentially you can think of these virtual particles as temporary photons as carriers that dont exactly behave ver well with conservation of energy. The field is full of these non-conservative carriers for a very brief instant as a function of the mass of the carrier ...


0

If you had a neutral plasma (which can be the free charges in a metal) and you pulled the negative and positive charges apart and let them go, they would oscillate due to the electrostatic potential. This is an excitation known as a plasma oscillation. A Plasmon is the quasiparticle associated with plasma oscillations (analogous to phonons being the ...


2

There's no difference between plasmon and plasmon polariton. Both of them indicate the resonant excitations involving electromagnetic wave and collective electronic motions simultaneously. "surface" stresses that the excitation in many cases occurs at the interface of a metal and a dielectric. However, there exist bulk plasmons as well. So "surface ...


5

The QFT for the scalar is considered to be massive for a very good reason: it is infinitely unlikely for the mass to vanish. There is no symmetry principle that would protect the scalar field from acquiring a generic mass. (The gauge symmetry is the principle that protects the masslessness of the photon but the scalar fields can't sacrifice to lose ...


1

This is how an experimentalist sees this part of the question ( the wave/particle duality has been addressed). So, if photons invariably appear to exhibit the characteristics of virtual particles, As described in Frederic's answer, all internal lines in Feynman diagrams are called by a virtual particle's name. In the plot in his answer it is called a ...


6

Short answer: A virtual particle is not the opposite of a classical particle. While the other answer captures some aspects correctly, there are still a few flaws and inaccuracies which in the following, I will try to set straight. Wave-particle duality Strictly speaking, quantum objects are neither waves or particles. They are entities behaving like ...


11

Photons do not exhibit the property of virtual particles, but it is not your reasoning that is faulty, you have simply fallen prey to an imprecise use of terminology. Let me start with my view of the wave/particle duality. Most of the images of "particles" and "waves" comes from a time when we really didn't understand the quantum world, and some ...


2

It is an intriguing question if one can formally do this. Classically the electric field might be considered as a limiting case of the electromagnetic radiation where the wavelength goes to infinity. I have answered a similar question here, where I refer to an analytic demonstration of how classical electromagnetic radiation emerges from a great ensemble of ...



Top 50 recent answers are included