In a shallow pit in southern France, the slow descent of a 1,100-tonne steel wedge marks humanity's incremental advance toward one of its oldest energy ambitions. Six of nine massive sectors now form the core of ITER, the world's largest experimental fusion reactor — a machine built by 35 nations not to generate electricity, but to answer a question: can the power of stars be harnessed at scale, cleanly, on Earth? The project has arrived ahead of its own expectations, a rare grace in an endeavor measured in decades.