> We could as well say that proton has 3 and electron is -3 charge? Absolutely! In fact that would have been much more convenient, since the "quantum of charge

> We could as well say that proton has 3 and electron is -3 charge? Absolutely! In fact that would have been much more convenient, since the "quantum of charge" appears to be 1/3 of the charge of the proton. All units of charge we've ever observed seem to be integer multiples of 1/3e.