The “moving sofa problem,” a puzzle that has remained unresolved since it was introduced in 1966 and memorably illustrated in the sitcom Friends, may finally have an answer. Baek Jin-eon, a 31-year-old research fellow at the Korea Institute for Advanced Study, has
produced a proof showing that no shape with an area greater than approximately 2.2195 square units, measured relative to a corridor of unit width, can complete the turn. The research was named one of the top
10 mathematical breakthroughs of 2025 by Scientific American.