On page 92 (Figure 58) Feynman states:
"The amplitude for a coupling is a number that I will call j; it is about
negative .1 for the electron (this number is sometimes called the "charge").
Charge?? I don't get it.
Would appreciate an explanation?
I am reading Feynman's QED.
On page 50 he states " The probability of an event is equal to the square of the length of an arrow called the "probility amplitude".
What, if any, is the relationship between Feynman's "arrow" and Shroedinger's wave function "psi".