Origins of the electromagnetic force

[Crapsghetti]

I saw a very old post where someone asked where an electron gets it's charge. Where does the charge come from? Doesn't it arise from the interaction with photons? My understanding is that electric charge and magnetism can not exist without photons, and the electron itself most likely could not exist independent either, a kind of relativistic quality. Can a single photon ever exist in a void without electrons? I don't think so.

I suppose that the electromagnetic force is created by an exchange of photons between charges, but is the charge itself also created by this photon interaction?

 

[DennisN]

I suppose that the electromagnetic force is created by an exchange of photons between charges, but is the charge itself also created by this photon interaction?

Hi Crapsghetti, and welcome to PF! Electric charge is an intrinsic property of particles, i.e. it is there from the beginning, i.e. it is not created by any interaction. "Where do these charges come from?", or, better put, what is the origin of these charges? We have no information about that (today) - it is simply a feature of the particles as we know them.

 

[bhobba]

Gauge Symmetry:
http://quantummechanics.ucsd.edu/ph130a/130_notes/node296.html

Thanks
Bill

 

[Crapsghetti]

Seems like an interaction to me. Can you really have a charge that doesn't emit photons? Can you have a photon that did not come from a charge? They seem linked to me. With out one the other can not exist.

 

[DennisN]

Question 1 to consider: How do you get from

Can you really have a charge that doesn't emit photons? Can you have a photon that did not come from a charge? They seem linked to me. (my bolding)

to

but is the charge itself also created by this photon interaction? (my bolding)

Question 2 to consider: Where do the fractional electric charges ($\pm 1/3$, $\pm 2/3$) of the quarks/antiquarks come from?

 

[Bill_K]

I saw a very old post where someone asked where an electron gets it's charge. Where does the charge come from?

The same place that the electron came from.

 

[DrChinese]

Can you have a photon that did not come from a charge?

Yes. Some non-linear crystals will split 1 photon into 2 photons.

 

[kurros]

Seems like an interaction to me. Can you really have a charge that doesn't emit photons? Can you have a photon that did not come from a charge? They seem linked to me. With out one the other can not exist.

Well the electric charge of a particle is *defined* to be the strength with which it couples to photons. So if there were no photons to couple to, then electric charge would be meaningless.

 

[bhobba]

Seems like an interaction to me. Can you really have a charge that doesn't emit photons? Can you have a photon that did not come from a charge? They seem linked to me. With out one the other can not exist.

You can - there is no mathematical reason you can't have a property of charge with no field and conversely. But when you go into the math, notably the gauge symmetry view, one practically screams out for the other. To be specific given the electric field E you define ∇.E = p and show that p, plus a few reasonableness assumptions, has all the properties of that interesting thing called charge - specifically charge density.

The following by Kobe gives the detail if you can get a hold of it:
http://inspirehep.net/record/157843/citations

Thanks
Bill

 

[Crapsghetti]

Yes. Some non-linear crystals will split 1 photon into 2 photons.

Hmm... but the original photon must have come from a charge and the 2 photons might as well be one, right? My understanding of quantum physics is pretty naive lol. I guess a photon could create a photon. So, you got me.

 

[Crapsghetti]

Question 1 to consider: How do you get from


to


Question 2 to consider: Where do the fractional electric charges ($\pm 1/3$, $\pm 2/3$) of the quarks/antiquarks come from?

Okay, so you are saying that there is an interaction, but the they do not create each other.

And for your question 2, it's the exchange of gluons, duh! Can a gluon exist without a quark? Can a quark exist without gluons?

 

[Crapsghetti]

You can - there is no mathematical reason you can't have a property of charge with no field and conversely. But when you go into the math, notably the gauge symmetry view, one practically screams out for the other. To be specific given the electric field E you define ∇.E = p and show that p, plus a few reasonableness assumptions, has all the properties of that interesting thing called charge - specifically charge density.

The following by Kobe gives the detail if you can get a hold of it:
http://inspirehep.net/record/157843/citations

Thanks
Bill

That is very interesting. I will try to read that later. I'm in a biochemistry internship. I don't know why I like physics. I think it's just because I like to think about stuff.

Anyway, sorry for the three posts in a row. I don't see how that kind of thing is bad forum etiquette. To me, it neatly spaces out each reply I gave to each poster. It is at least an organized way of triple posting.

Hosanna!