It turns out the physics of curling is really, really complicated

A pair of Canadian scientists believe they may finally have an answer to how a curling rock curls.

Pair of Canadian scientists believe they may finally have an answer to how a curling rock curls

Mark Shegelski of UNBC draws out the formula he belives explains how curling rocks curl. (University of Northern British Columbia)

When 1980s TV star Mr. T revealed his love of curling on Twitter this week and told his followers, "It's not as easy as it looks," he likely didn't know how right he was. Because as it turns out, the physics of how curling works has still not been settled — although a pair of Canadian scientists believe they may finally have an answer.

The paper, titled, "First principles pivot-slide model of the motion of a curling rock," proposes an algebraic formula to explain the relationship between the curling rock and the pebbled ice on which it is thrown to explain how it curls down the ice.

"It's magnificent to have an equation like this, it's unbelievable," one of the paper's authors, University of Northern British Columbia physicist Mark Shegelski told CBC Daybreak North host Carolina de Ryk.

He said he's been curious about the science of curling ever since he started playing the game as a student in the 1980s. 

"The things that the curling rocks were doing, for my physics mind, were extremely interesting," he said.

He was particularly interested in "curl distance" — the sideways motion the rock travels while moving down the ice. He noticed the amount of spin on the rock didn't seem to have any effect on that distance.

"It doesn't matter how many times the rock rotates. Twice, two full turns or 10 full turns, the [curl] distance it travels is pretty much the same. And when you think about that, it's astonishing... it doesn't make sense."

Canada skip Kevin Koe and other curlers have posed a mystery to physicists for years, who have so far been unable to explain just how curling rocks curl. (Michael Burns/The Canadian Press/Curling Canada)

Unable to find any other curlers who were as interested in the subject as he was, Shegelski kept the question in the back of his mind for years, working on various models with other scientists.

His latest breakthrough, published in the journal Cold Regions Science and Technology this month, is the result of a collaboration with Edward Lozowski, professor emeritus with the faculty of science at the University of Alberta.

For his part, Lozowski said the formula took "hundreds of pages of equations" and years of work to solve what he thought would be a relatively simple equation.

Mr. T said said on Twitter he appreciates learning about curling, so the science of the sport may be right up his alley. (Brad Barket/Getty Images)

In the past, scientists who looked at the sport simply assumed the "curl" of a curling rock was affected by friction with the ice.

But, he said, it seems as if the textured bottom of the rock, known as the running band, actually binds to each pebble of ice, then pulls it to the breaking point. The rock then lurches ahead, and curls.

Shegelski described it as a series of slides and pivots spread out over the duration of the rock's journey down the ice.

Lozowski said he's not sure that understanding the science of the game will give Olympic-calibre competitors any future advantages, but Shegelski believes it could change the sport for recreational curlers.

He's patented a design for a curling rock with a larger running band diameter that should allow newcomers to have more curl in their game, emulating the experience of top-level players.

Though he has no plans to actually construct the rocks, with Mr. T's hashtag #curlingiscoolfool taking off, the demand may soon be there.

With files from CBC Daybreak North and CBC Edmonton AM

About the Author

Andrew Kurjata

@akurjata

Andrew Kurjata is a radio producer and digital journalist in northern British Columbia, situated in the traditional territory of the Lheidli T'enneh in Prince George. Email: andrew.kurjata@cbc.ca | Twitter: @akurjata | Secure PGP: http://www.akurjata.ca