B How and why do quantum fields interact with each other?

[Daniel Bolstad]

Why is it that quantum fields interact? How do they do this? Does every exitation of any field affect all other fields?

I'd appreciate an explanation that uses as little math as possible, I don't have a science background.

 

[ZapperZ]

Why is it that quantum fields interact? How do they do this? Does every exitation of any field affect all other fields?

I'd appreciate an explanation that uses as little math as possible, I don't have a science background.

Then maybe you need to first explain to us what you mean when you ask "quantum fields interact". You seem to be using familiar terms, but it doesn't seem to feel as if you are aware what they are.

For example, what makes you think that "every exitation of any field affect all other fields"? Where did you get this, and where did this come from? Do you have an example of this to support your claim? The "weak interaction" doesn't interact with the EM interaction. If it does, then neutrinos won't be this difficult to detect and interact. This is what I mean by you are using familiar terms, but I don't think you know what they are.

So don't ask us why the color of the unicorn's horn is pink. Let's first establish that there IS a unicorn, i.e. establish that you actually know what "quantum field theory" is to start with. Can you do that?

Zz.

 

[dextercioby]

I'm afraid the OP has asked for explanations of things way above his head, so we can't formulate any answer that he could understand.

 

[DrDu]

If fields wouldn't interact, they would not be observable. The problem is that nobody knows how to exactly treat interacting fields. So we have to use clumsy perturbation theory starting from free fields crossing our fingers that it may describe something remotely similar to reality.

 

[ZapperZ]

If fields wouldn't interact, they would not be observable. The problem is that nobody knows how to exactly treat interacting fields. So we have to use clumsy perturbation theory starting from free fields crossing our fingers that it may describe something remotely similar to reality.

That is not the issue here. In many cases, we detect neutrinos not because its field "interact" with other fields, but because it has a small cross-section in scattering off atoms and electrons, and those electrons create the cherenkov radiation. That's how we detect them, but this is not "weak interaction interacting with EM interaction". And we know that leptons certainly do not participate in the strong interaction.

The OP just need to really explain a lot more here, especially on where he/she got such ideas, because I have a strong feeling that the context is missing.

Zz.

 

[DrDu]

In many cases, we detect neutrinos not because its field "interact" with other fields, but because it has a small cross-section in scattering off atoms and electrons[...]

Doesn't scattering off the electrons qualify as an interaction?

 

[ZapperZ]

Doesn't scattering off the electrons qualify as an interaction?

Yes, but this is via the exchange of W or Z boson, not W/Z with photons. It is not interaction within the same type. It is the interaction with another "specie" that is the issue here.

Zz.

 

[vanhees71]

Well, if you have a question that doesn't allow me to give an answer, I just don't respond ;-)). QFT is not communicable without math!

 

[DrDu]

Yes, but this is via the exchange of W or Z boson, not W/Z with photons. It is not interaction within the same type. It is the interaction with another "specie" that is the issue here.

Zz.

Of course, but if the neutrino would not interact weakly with the electrons and the electrons with the em field, i.e. if one field would totally decouple from the rest, we would not have any means to observe it. So we are forced to consider interacting fields.

 

[ZapperZ]

Of course, but if the neutrino would not interact weakly with the electrons and the electrons with the em field, i.e. if one field would totally decouple from the rest, we would not have any means to observe it. So we are forced to consider interacting fields.

But the 2nd part is "optional". We just happen to get a particle that couples to the EM field. It doesn't have to be that way all the time, which may explain why we don't detect neutrinos efficiently, despite its abundance (i.e. we are oblivious its many other interactions). And once the electron is out, it is like any other electron.

So yes, in my view, they are decoupled, and only if the resulting interaction can produced detectable (EM) interaction can we observe it.

Zz.