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Feynman Diagrams

Why is it interesting?

Feynman’s diagrams and rules were a sort of bookkeeping-by-picture process that miraculously captured all the details of the standard model in a series of diagrams; they allowed people less talented than Feynman to perform the most complex calculations carefully and correctly. Many of the great advances in physics are like this; they codify and make routine what was formerly almost impossible to think about.Whenever I have a new problem to work on—in physics or options theory—the first major struggle is to gain some intuition about how to proceed; the second struggle is to transform this intuition into something more formulaic, a set of rules anyone can follow, rules that no longer require the original insight itself. In this way, one person’s breakthrough becomes everybody’s possession.

From My Life As A Quant by Emanuel Derman

Julian Schwinger once said rather bitterly that "Feynman brought quantum field theory to the masses," by which he meant that any dullard could memorize a few "Feynman rules," call himself or herself a field theorist, and build a credible career. Generations learned Feynman diagrams without understanding field theory. Heavens to Betsy, there are still university professors like that walking around!

from the preface of Feynman's The Strange Theory of Light and Matter by A. Zee

Layman

Explanations in this section should contain no formulas, but instead colloquial things like you would hear them during a coffee break or at a cocktail party.

Student


Feynman Rules Resources:

  • "When performing a full calculation within the Standard Model or its extensions, it is crucial that one utilizes a consistent set of signs for the gauge couplings and gauge fields. Unfortunately, the literature is plagued with differing signs and notations. We present all Standard Model Feynman rules, including ghosts, in a convention-independent notation, and we table the conventions in close to 40 books and reviews." from A resource for signs and Feynman diagrams of the Standard Model by Jorge C. Romao

Researcher

The motto in this section is: the higher the level of abstraction, the better.
Common Question 1
Common Question 2

Examples

Example1
Example2:

History

It struck Feynman that everyone had a favorite principle or theorem and he was violating them all… Feynman knew he had failed. At the time, he was in anguish. Later he said simply: “I had too much stuff. My machines came from too far away.”[…] Schwinger’s students at Harvard were put at a competitive disadvantage, or so it seemed to their fellows elsewhere, who suspected them of surreptitiously using the diagrams anyway. This was sometimes true… Murray Gell-Mann later spent a semester staying in Schwinger’s house and loved to say afterward that he had searched everywhere for the Feynman diagrams. He had not found any, but one room had been locked…from "Genius" by Gleick

advanced_tools/feynman_diagrams.1519484735.txt.gz · Last modified: 2018/02/24 15:05 (external edit)