The Algorithm That Lets Particle Physicists Count Higher Than Two | Quanta Magazine

Through his encyclopedic study of the electron, an obscure figure named Stefano Laporta found a handle on the subatomic world’s fearsome complexity. His algorithm has swept the field.

**Hasnain says:**

"By the late 1990s theorists had mastered predictions at the one-loop level, which might involve 100 Feynman integrals. At two loops, however — the level of precision of Gehrmann’s calculation — the number of possible sequences of events explodes. A quarter century ago, most two-loop calculations seemed unthinkably difficult, to say nothing of three or four. “The very advanced counting system used by elementary particle theorists for counting the loops is: ‘One, two, many,’” joked Ettore Remiddi, a physicist at the University of Bologna and Laporta’s sometime collaborator."