A 6 x 12 table showing all 72 diagrams needed for the calculation of α^3 corrections to the electron anomalous magnetic moment. Most of them resemble a triangle with solid lines emerging from the vertices. Additional lines representing the exchange of virtual particles crisscross within the diagrams, or veer out before curving back to rejoin the "internal" lines.

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1. Robert McNees (mcnees@mastodon.social)'s status on Thursday, 15-Dec-2022 16:59:04 UTC Robert McNees

   in reply to

   Luckily, this isn't a practical concern. Dyson's own crude estimate is that it happens somewhere around the α^{137} term in the series. That's miles away from anything we can calculate.

   Why does it happen? In Feynman's approach to perturbative QED calculations, the number of diagrams needed to calculate the αⁿ term in the series grows rapidly with n. Collectively, they eventually overwhelm even large powers of α.

   Diagrams: K.K. Gan, 3rd order contributions to electron anomalous magnetic moment