# Electric charge

Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?

jtbell
Mentor
How would you distinguish between a "deep" and a "non-deep" explanation?

How would you distinguish between a "deep" and a "non-deep" explanation?
:)
You're right.
So may I ask for any explanation exists, deep or non-deep.

Delta2
Homework Helper
Gold Member
According to standard model, electron is one of the elementary particles (electron is a lepton) and just has the charge it has symbolically -1. (cant go deeper than that).
Proton (again according to standard model) is a composite particle, consisting of 3 different kind of quarks,2 of the quarks (I think the up quark each one with different "color" ) have +2/3 charge each, while the down quark has -1/3. So total charge of proton is 2/3+2/3-1/3=+1. No deeper than that as far as I know.(the quarks are also elementary particles and just have the charge they have).

However I don't know how the charge of particles comes into play in String Theory, cause there the elementary elements are called strings and not exactly the same as particles.

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jtbell
Mentor
One can derive the existence of electric charge and the equations of electromagnetism (Maxwell's equations) by assuming that quantum-mechanical fields have the property of local U(1) gauge symmetry. This is the simplest description that I can find:

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

Most students don't study this until graduate school or maybe late undergraduate.

The weak and strong interactions can be generated from other local gauge symmetries, and are associated with their own kinds of "charge."

Dale
Mentor
2021 Award
Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?
As jtbell mentioned it depends largely on your definitions of "deep" and "nature". However, I would disagree with the statement and with my personal meanings for "deep" and "nature" I would point towards Noether's theorem.

One of the fundamental symmetries of the Lagrangian is the U(1) gauge symmetry. Per Noether's theorem a symmetry in the Lagrangian implies a corresponding conserved quantity. In this case the conserved quantity is a scalar field which we call charge.

Edit: I see jtbell was faster! And provided a reference.

Hello Dale, jtbell, and Delta2,
Thank you all for your kind replies. That will definitely help and I obviously have to read more about it since my initial understanding of charge was wrong.
Thanks again.
Regards,
Behrouz