A conjecture Harold Grad made in 1967 — that certain three-dimensional plasma equilibria for magnetic confinement cannot exist without special symmetry — has fallen to AI-assisted work. University of Maryland physicist Matt Landreman published explicit counterexamples on September 22, crediting GPT-6 Astra Pro with discovering the solutions, and says he manually checked every equation.

Landreman's preprint landed one day after a separate team published its own counterexamples with Lean 4 certification, so AI does not get sole priority. A follow-on paper submitted October 5 then gave Landreman's results and the remaining open questions to a team of Google DeepMind Gemini 4 Argon agents, which produced broader solutions that remove an additional symmetry restriction; the researchers checked those derivations independently, and they held up.

The result is mathematics, not a reactor: it supplies exact solutions useful for theory and numerical testing of stellarator designs, and it neither proves better plasma confinement nor changes any engineering timeline. It is, though, another data point that frontier models from two rival labs are now producing checkable research results on the same problem within weeks of each other.