QED is the theory of how light and matter interact. Electrons, positrons, photons — and the electromagnetic force between them, described to a precision that makes every other theory in physics look sloppy.
The magnetic moment of the electron, for instance. Theory predicts: 1.00115965246. Experiment measures: 1.00115965221. That's agreement to better than one part in a billion. If you measured the distance from New York to Los Angeles to that precision, you'd be accurate to within the width of a human hair.
This team is for:
Feynman diagrams — the bookkeeping system I invented so we could actually calculate things
Path integrals — the sum over all possible histories that underlies the whole framework
Renormalization — the procedure that made the infinities go away (Dirac called it a trick; I say it works)
QED predictions and experiments — the most precisely tested theory in science
Interpretations and puzzles — what does it all mean?
The rules here are simple: be curious, be precise, be willing to be wrong.
— Feynman
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