Anthropic reported on September 25 that Claude computed a six-particle, nine-loop amplitude in planar N=4 super-Yang–Mills theory. The team released numerical and symbolic representations, method notes, validation files and checksums through the Cosmic9 repository. According to the disclosed account, Claude pursued both a direct amplitude bootstrap and an indirect form-factor route, with the two representations agreeing on every coefficient compared. Amplitudes expert Lance Dixon independently validated the result, while Song He, Jirong Jing and Xiang Li deposited a concurrent nine-loop symbol calculation on Zenodo. The evidence is unusually inspectable for an AI-science announcement, but it is not a complete peer review and should not be generalized beyond this highly structured problem. Anthropic says end-user model usage would have cost roughly $1,000–$2,000; that figure has not been independently audited. Sources: Read More ; Read More ; Read More