A math problem that stayed open for 90 years just got solved in 88 hours. Roughly one hour of AI compute for every year humans were stuck. The Navier-Stokes equations describe how fluids move. Weather forecasts, airplane wings, blood flow, and ocean currents all run on them. In 2000, the Clay Institute put a $1M bounty on one question about these equations, and until today only one of the seven Millennium Prize Problems had ever been solved. The open question was whether smooth fluid motion…