Curling has been around for a long time, originating in Scotland in the 1500s. Over the centuries, it’s become an international game, and a winter Olympic spectacle famous for its peculiarity. The strangest thing about curling, though, isn’t how it looks, but rather, how it works—even after decades of research, physicists can’t agree on why curling stones curl. The controversy isn’t merely academic. Curling is all about accuracy, and you can steer the stone more effectively if you understand the mechanics of the game. Watch the video above to hear researchers describe some of the leading theories on the physics of curling, and see how their work has dramatically changed the sport.