Garnet Chan never bought the idea that certain chemical mysteries demanded quantum computers. For years the Caltech chemist pushed back against claims that systems like the iron-molybdenum cofactor at the heart of nitrogenase lay beyond classical reach. Last month his team delivered the proof. They computed the ground-state energy of the FeMo-co cluster to chemical accuracy. All on ordinary machines. The Quanta Magazine report lays out how this decades-long effort upends assumptions that have driven millions in quantum hardware investment. Nitrogenase turns atmospheric nitrogen into ammonia. Bacteria have done it for billions of years under ambient conditions. Industrial Haber-Bosch plants require high heat and pressure. Understanding the enzyme’s mechanism could reshape fertilizer production or catalyst design. Yet the electronic structure of its active site has resisted precise calculation. The cofactor contains seven iron atoms with highly entangled electrons.…