QED Attraction and Repulsion

Most recent answer: 06/09/2011

Q:
I read Feynman's QED, and it totally blew my mind. Something important that I feel he has glossed over, however, is why positive charges attract negative charges. I can understand that negative charges repel because electrons they have a high probability of "shooting" photons, causing themselves to be knocked back like a person firing a bazooka. The photon then is absorbed by the other electron, knocking it in the other direction. But why should protons attract electrons? Do the photons go "behind" knocking them in towards eachother? But in that case, why wouldn't that happen with two electrons?
- Noah Miller (age 14)
New York, New York, USA
A:
Noah- That's a great question, but I have bad news. Although the answer is well known to people who are deeply immersed in quantum field theory, I'm not one of them. The guy who usually helps me out on these questions says that there's no way to explain it to me for translation to you.

One thing I can say though. If your appealing picture of the e-e repulsion were correct, then as you say it would lead to the wrong results for e-p. Therefore it isn't right. My friend the expert emphasized this point.

Mike W.

p.s. I have a quibble with Feynman's QED. At several points he insists that we should really think of the electrons etc. as particles. He never says quite what that means. The math all is of a form that fits a picture of always having extended quantum states, with no need for any separate talk about particles.

(published on 06/09/2011)