Anthropic’s Claude solves nine-loop amplitude challenge in theoretical physics

Physics has a category of problems that are technically straightforward to describe and brutally hard to solve. Scattering amplitude calculations fall squarely in that category. They tell physicists what happens when particles collide, and the more precision you want, the more computational loops you have to work through. Each additional loop multiplies the complexity by an almost absurd factor. Anthropic’s Claude just cleared nine of them. On September 25, 2026, Anthropic announced that its physicists Liam Fitzpatrick and Siddharth Mishra-Sharma had used Claude to compute the six-particle scattering amplitude in planar N=4 super Yang-Mills theory at nine loops. That sentence is a mouthful, but the short version is this: the AI completed a calculation that represents the current frontier of a subfield that has occupied some of the world’s sharpest theoretical minds for decades. What was actually computed, and why it matters N=4 super Yang-Mills is a theoretical model physicists use as a kind of sandbox. It shares structural features with the theories that describe real particle interactions, but it’s clean enough to be mathematically tractable. Scattering amplitudes in this model t...