What if photons had an electric charge?

[jewbinson]

What would happen if all photons had (slight) electric charge?

Would we just not be able to see?

Or would we not exist at all?

Why?

If they were negatively charged, would they repel electrons and attracts to the nucleus of an atom? What consequence would this have?

 

[xts]

They can't have any. Charged particle can't be massless.

 

[jewbinson]

Okay, so photons are massless?

I just read there is an upper bound on the mass of a photon and that it is currently believed that photons have no mass, but it is an uncertainty.

If the mass were lower than the upper bound, then what would the effects be?

 

[xts]

Photons are massless - what is a very foundation of Relativity Theory. You probably read some article about seeking experimental evidence contradicting Relativity. They measured mass of the photon and found it cannot be bigger than some (small) value, but may be 0.
So that experiment (although pretty worth: never to many cross-checks in science!) was not able to falsify Relativity.

 

[JeffKoch]

Charged particle can't be massless.

Hmm, is that strictly true? It's not obvious to me why that would have to be true.

 

[xts]

I am not theoretician, so maybe there exist some weird theories solving a problem of inertia of electromagnetic field.

For my simple mind, charged particle creates electric field, which has some non-zero energy, thus it must carry at least its corresponding relativistic mass.