2

On page 91 in the Penguin edition, in the chapter "Electrons and Their Interactions", Feynman writes:

There is no complicated formula for an electron to emit or absorb a photon: it doesn't depend on anything - it's just a number! The junction number I will call $j$ - its value is about -0.1: a shrink to about one tenth, and half a turn.

My question: What is the exact meaning of "half a turn"? What is its correspondence in the usual formulae? Does the "half a turn" mean that the electron arrow that Feynman always talks about changes direction after emitting the photon?

(Feynman adds a footnote saying that j is the amplitude to emit or absorb a photon, and is often called the "charge" of a particle.)

Qmechanic
  • 201,751
frauke
  • 684
  • Half a turn means the phase of the number is 180°. Complex numbers can be written in terms of their magnitude and phase, for example -0.1 has magnitude 0.1 and phase 180°, 1+i has magnitude $\sqrt{2}$ and phase 45° – bemjanim Feb 26 '20 at 12:37

0 Answers0