The problem
The Clay Mathematics Institute's Millennium Prize problem on the Navier–Stokes equations can be won by proving any one of four statements: global regularity on (A) or on the torus (B), or breakdown on (C) or on the torus (D). The breakdown statements allow a smooth external force.
What AI did
On 8 September 2026 OpenAI announced that a new internal model had shown that an initially smooth fluid, starting at rest, can develop a singularity in finite time under a smooth external force, with finite energy throughout. This is a blowup result, not global regularity; OpenAI says it establishes statements C and D. According to OpenAI, about 10,000 concurrent agents reached the result on 5 September after about 88 hours, and GPT-6 Astra then took 17 hours to formalize it in Lean. OpenAI also claims an unforced blowup for the Euler equations, and says it will not claim the prize.
How it was checked
The Clay Institute's note of 11 September says the problem "has apparently been settled" and describes its process as "deliberately unhurried"; it has not accepted the result. A paper of 6 October (arXiv:2610.08144) argues that the Lean proof does not correspond to the written proof, citing mistranslations, though it does not claim the result is false. Javier Gómez-Serrano told NPR that "the community seems to have the consensus that it is correct", and also that "the paper is not written for humans".
Limitations
The result relies on the smooth, unphysical external force that Clay's statements C and D allow. Priority is disputed: Tristan Buckmaster and Levent Alpöge obtained forced smooth blowup for related equations (including 3D Euler) in August with heavy use of AI, and Buckmaster alleges that OpenAI had prior knowledge of their work; OpenAI denies that his prompts could have influenced its system and credits them with priority for forced Euler. Until the proof is checked independently, we grade it "unverified".
∎