Schwinger was first to work out how to do quantum electrodynamics, but his methods were incredibly difficult and cumbersome. Feynman hit upon a much simpler approach – his famous diagrams – which turned out to be equivalent, but vastly easier to use. Schwinger, as I remember the story, was never seen to use a Feynman diagram. But he had a locked room in his house, and the rumor was that that room was where he kept the Feynman diagrams he used in secret. What’s the equivalent of Feynman diagrams?

Source: New York Times September 16, 2018 19:22 UTC