For decades, physicists suspected that graphene's electrons, moving too swiftly to feel one another's repulsion, concealed a hidden world of correlated quantum states just beyond reach. A research team has now built a slower version of that world — a twisted bilayer of molybdenum diselenide whose moiré geometry reduces electron velocity a hundredfold — and watched long-predicted Mott insulator phases emerge from the stillness. The discovery, made in 2026, suggests that the act of engineering a material's geometry is itself a form of scientific inquiry, one that lets us tune the laws of interac