Moving charges: Describing its field as photons

[McLaren Rulez]

Hi,

I was studying Cherenkov radiation and here's what I read. A charged particle moving through a medium has an electric field. This is equivalent to the particle emitting photons which are absorbed by the atoms of the medium and causes them to reorient themselves.

I am a little uncomfortable with the electric field being viewed as photons. For instance, a static electric field has nothing to do with photons. Also, electromagnetic radiation is quantized as photons. But a moving charge seems to be something in between the two so how is it explained? And does this mean that a moving charge (just moving, not accelerating) emits light? I'm quite muddled about this connection so I'd appreciate an explanation or a good source.

Thank you!

 

[vanhees71]

A classical electromagnetic field is not described by photon-Fock states but by coherent states. I don't know, why many people think the photon picture is better than classical electromagnetic fields, if you deal with a situation where classical electromagnetics applies!

 

[Fr34k]

The photons are used when you want to describe interactions of particles. Ie. if you have 2 electrons with their own electric fields. "How do they know where and what the other one is"? It's easier for us to imagine that they exchange something that gives both a sense of their surroundings, in this case a photon.
Now for Cherenkov light, actually particle doesn't emitt light, the medium does. When a particle faster than light in that medium travels through it, it "rearranges" the molecules and atoms with it's field, or as your professor put it, it gives off imaginary photons so the atoms in material "see" where particle is and where is it going. When the particle passes the molecules and atoms rearrange themselves back and that emitts photons you see as Cherenkov light.

 

[McLaren Rulez]

Thank you. I think I get it now.

 

[sardar]

Hello,

Thank you for sharing your thoughts on this topic. I can understand your discomfort with the idea of describing a moving charge's electric field as photons. It is important to note that while photons are the fundamental particles of electromagnetic radiation, they are also the carriers of the electromagnetic force. This means that any interaction involving the electric or magnetic fields can be described in terms of photons.

In the case of a moving charge, the electric field is constantly changing as the charge moves, and this changing field can be thought of as a stream of photons being emitted and absorbed by the surrounding atoms. This is known as the wave-particle duality of light, where light can behave as both a wave and a particle.

To answer your question about whether a moving charge emits light, the answer is yes. However, the amount of light emitted is very small and not visible to the naked eye. This is because the emission of photons is a continuous process and the energy of each photon is very small, making it difficult to detect.

I would recommend further reading on the topic of wave-particle duality and the connection between moving charges and photons. It is a complex concept, but it is an important aspect of understanding the nature of light and the behavior of electromagnetic fields.

I hope this helps clarify the connection between moving charges and photons. Thank you for your question and curiosity on this topic.

Best,