Expert: James J. Kovalcin - 5/10/2005

Question
I wish to know the state of the art in measuring the charge of electrons and protons.  Do all electrons have the same  electric charge?  Exactly the Same?  to what level of accurancy?  Can we assume or prove they all have exactly the same to an infinate number of decimal places, otherwise the charge of protons and electrons would not balance out?  Or does quantum fluctuations allow for variations in the charges which would 'roughly' balance out, so an infinate level of exact match is not required?  Thanks for you help.

Answer
All electrons are COMPLETELY and EXACTLY identical. It is NOT possible to tell the difference between two different electrons. And yes, every electron has EXACTLY the same charge.
We can never PROVE such a thing, but we have never measured the charge of any electron [or muon, or pion, or proton or any other fundamental particle] to have a charge any different.
Assuming is always risky!
I am not sure what you are getting at with "the charge of protons and electrons would not balance out?"
Any time we generate a positive charge in the laboratory an identical negative charge is always formed. The reverse is also true!