# Science Behind Olympic Curling Confuses Viewers And Physicists Alike

The U.S. men’s curling team, who took home the gold, were surprised when they were accidentally awarded medallions that read “Women’s Curling” on Saturday. But that’s likely not the only thing that surprises them. In fact, the sport itself has left scientists in awe too.

If you’ve never watched the fascinating sport, here’s a quick rundown of what curlin—“the roaring game”—involves: two teams of four players each slide stones on a sheet of rectangular ice, with the goal of landing it as close as possible to the intended target. The term “curling” comes in because when the stone glides across the ice, it curls similar to a bowling ball curving down a lane. The team to collect the most points, wins.

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But exactly how the 42-pounding stone curls, as players sweep the ice to guide it toward its target, remains a mystery.

“Anything unusual gets us excited, and a curling rock has that,” Ray Penner, an astrophysicist at Vancouver Island University who has studied the physics of the sport, told The Wall Street Journal.

There have been quite a few theories that have tried to explain why, unlike other objects, curling stones—also called rocks—spin in the same direction as which it was rotated. Whereas other items, for example a bowl, will curl right if you spin it counterclockwise and slide it along a surface, as demonstrated in the NOVA PBS video below.

One theory—called the stick-slip friction theory—points to the “pebbled” ice. The physicists behind that theory believe that the stone briefly catches onto those pebbles and causes the rock to slide the way that it does. However, not everyone has bought into the mathematical model, which concludes all speeds of rocks spin the same, the scientists have proposed.

If the theory held true, a faster spinning stone would be likely to curl more, Mark Denny, a former aerospace engineer, explained to the Wall Street Journal.

“I have come up with similar curling theories and they have fallen down for similar reasons,” Denny said.

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Another theory explains that only a thin ring of the stone is in contact with the ice at any given time. The ring makes small indentations in the ice. The indents then work to guide bumps on the back of the stone to allow it to curl, MPR News reports.

Despite the sport being around since as early as the 16th century, scientists have yet to agree on a theory.