Harold Grad's 59-year-old fusion physics conjecture falls as two papers find counterexamples

IgorCarron · x · 2026-09-28

A 59-year-old conjecture in fusion physics has fallen. Harold Grad (1967) argued that smooth 3D plasma equilibria cannot exist unless pressure is constant or symmetry is present. This week, two independent papers posted a day apart presented three families of counterexamples — two reportedly found with GPT-6 Astra. The result is a big deal for stellarator design, expanding the space of viable smooth 3D equilibria.

Original post →

More from Research

Research channel →