Tagged Questions
4
votes
1answer
104 views
Mass gap for photons
I am puzzled by the answers to the question:
What is a mass gap?
There, Ron Maimon's answer gives a clear-cut definition, which I suppose applies to any quantum field theory with Hamiltonian $H$, ...
2
votes
1answer
94 views
Photons, where do they come from? [closed]
Photons, where do they come from?
What exactly is a photon?
I've certainly heard how they get produced, but it doesn't seem to make sense that some sort of particle should need to be produced just ...
0
votes
0answers
49 views
How does QED deal with wavelength of quanta [duplicate]
Since QED treats photons as individual units (quanta) how does it treat the concept of the "wavelength" associated with the photon?
3
votes
0answers
100 views
Quantum Electrodynamics
I was wondering if anyone could give a simple explanation of how light interacts with matter. From what I have read in QED, electrons will repel each other because of their ability to emit and ...
4
votes
1answer
119 views
Are there 2 kinds of photons, one that mediate the electromagnetic interaction and the other the quanta of light?
It is usually said that photons are the force carriers or the mediators of the electromagnetic forces between electric charges. At the same time we know also that electromagnetic waves on the quantum ...
0
votes
2answers
155 views
Why does Quantum Electrodynamics Allow a Photon to Exist Temporarily as a Positron and an Electron?
In this question...
Why does a photon colliding with an atomic nucleus cause pair production?
...I asked why a photon colliding with a atomic nucleus can become an electron and a positron. The ...
1
vote
1answer
102 views
Two-photon scattering: colours
Is there a particular conservation principle that necessitates that the outcoming photon pair has the same frequencies as the incoming photon pair?
I'm thinking in particular of these Feynman-like ...
1
vote
0answers
60 views
Photons interact with themselves
We know that photons are the antiparticles of themselves and if they interact with each other through higher order process do they annihilate and again produce photons?
Here is the Phys.SE question ...
0
votes
0answers
52 views
Electromagnetic charge [duplicate]
Possible Duplicate:
If electromagnetic field give charge to particles, does photon carry charge?
Is it possible to charge photons
I was wondering if light when it's in wave form (seeing ...
3
votes
3answers
631 views
Why/how does an electron emit a photon when decelerating?
I've had two special relativity courses so far but none really gave me a clear description of the process.
2
votes
1answer
81 views
Is there a point interaction model of the electron?
Is there a point interaction model of the electron? Is there a point interaction model of the electron? I imagine something like $\propto(\bar \psi\psi)^2$ (edited). Is such a thing in use?
Since I ...
6
votes
2answers
475 views
Deriving Planck's radiation law from microscopic considerations?
In the usual derivation of Planck's radiation law, the energies or frequencies $\omega$ of the oscillators depend on the measurements $L$ of the black body. The model is such that the only ...
3
votes
1answer
338 views
Why can't we make measurements in a photon's rest frame when loop diagrams make measurements possible?
It is one of the axioms of special relativity that the photon has no rest frame; light travels at speed c when measured in any inertial frame of reference. As a corollary, it is often said that if one ...
2
votes
1answer
143 views
For someone who only studied electromagnetism, what is the modern way to explain electromagnetic fields?
After reading most of the electromagnetism chapters of Feynman's lectures on physics, I would like to understand in more detail, at least an idea, of what causes the electromagnetic fields. Not sure ...
1
vote
2answers
237 views
Photon emission from excited atoms
the answer given by classical quantum mechanic to the for atomica levels does not provide that an electron in an excited levels can radiate a photon and move to a lower level. How QED justifies this ...
2
votes
6answers
2k views
Why can't photons have a mass
Why can't photons have a mass? Could you explain this to me in a short and mathematical way?
6
votes
3answers
2k views
Properties of the photon: Electric and Magnetic field components
Consider an electromagnetic wave of frequency $\nu$ interacting with a stationary charge placed at point $x$. My question concerns the consistency of two equally valid quantum-mechanical descriptions ...
