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Welcome to the Science Talk, the weekly podcast of Scientific American posted on February 18th, 2010. I am Steve Mirsky.

And you know what the hottest sport in the world is right now? Thanks to the Winter Olympics, it is, of course, curling. That's the one where the guy slides  the big heavy rock down the ice while two other guys furiously sweep the ice in front of the moving rock. Or maybe you've seen this fairly hilarious¹ commercial on NBC promoting Olympic curling.

"This skip brings the hammer, you know some only push this one too thin."

"Nice stroke!"

"Oh, it's got a good line!"

"Good line. "

"Down the sheet, it then comes!"

"This one's got a chance! (It's got it.)Oh, went to the house(It's got it.). Until moves steal a goal. These until moves steal a goal. The American attempt to deliver a message. Not in my house! Not time!"

The spike² in curling interest prompted David Letterman once and I to say..."

"I told the excitement of a shuffleboard curling. Uh, but household insurers, you know, it just..."

In this top 10 list of surprising things about curling No.1 was-no one cares. But we know that's not true, we know that you care. Because curling is all about physics which is why four years ago after the last Winter Olympics, I interviewed a scientist named Mark Shegelski from University of Northern British Columbia. He studies curling physics. Back then this program had a different format³ of short interviews and I run only five minutes of the conversation I had with Shegelski. But with more time now to talk, I went back and I re-edited the entire long conversation I had with him. So sit back with some hot cocoa. And maybe intro physics textbook because here we go.

"You are not a full-time⁴ curling physicist⁵. What do you do with most of your time?"

"Well, most of the time I am teaching. Roughly 30 percent of the time or 40 percent of my time go to research. And my research currently in the area of  quantum mechanical tunneling in decay."

"People might not have heard of quantum tunneling in decay. Can you  briefly⁶ explain what that is?"

"Well, if you imagine a marble inside of a ball, and it’s rolling around in that ball, if it doesn't have enough energy to get ride out to the top, it's going to stay in the ball. And it won't ever get outside. If you then consider the cause of the same problem but on a quantum mechanical field. So you are thinking of, for example, of a particle such as an electron. If it is experiencing the same kind of  potential, it's in the well of ball and there is a barrier that the electron needs to overcome to get outside. What is found is that, well-known is that particles emerge from inside of the potential ball of the potential well, and they emerge outside with less energy than we use needs to have clear the barrier, in other words, the energy of the particle is below the maximum of the potential well for the particle."

"So they have snooker right through the wall?"

"So, yeah. They were tunneling come from, it’s this, thinking about from our  everyday experience, it’s this, the particle somehow tunneled through this barrier, the potential that had to get over and they got out with less energy than they have to get over. So from an everyday experience, point of view, from an everyday point of view, you couldn’t really understand that except this, somehow they are so true. The detail of quantum mechanics to find out how this happens. And there’re some problems that are still need to be solved in this area and that's the area that I am looking at."

"So one of the really weird⁷ things about quantum mechanics, but…"

"Yeah, pretty much. Most things about quantum mechanics are in  opposition⁸ to our regular everyday experiences. So I wanna first thing, students have to do in learning quantum mechanics is that they have to give up the regular everyday ideas that we have and adapt a new way of looking at things. And that's since quantum mechanics is quite difficult because it isn't something that you experience on the daily basis. "

"And that brings we to curling, believe it, right? I know that you have done some scholarly studies of the physics of curling. And the reason I got in  touch was, I was watching curling during the Olympics and you see these people furiously sweeping⁹ the ice in front of these big heavy grounded rocks. It’s going down the ice. Then, what are those sweepers actually  accomplishing from the physics point of view?"

"Oh,there are several things. The most important one is that by sweeping in front of the ice, you are reducing the friction¹⁰ between the rock and the ice. And let's just stay with that for a bit, with the reduce of friction the rock still flows down, but it doesn't flow down as quickly. And so therefore, if you sweep a rock vigorously in front, if you sweep the ice in front of the rock, you can actually make the rock go quite a bit further than it would go if you  didn't sweep."

"And, what is actually happening when you sweep? Are they melting the  surface?"

"Okay, to get an answer to that. On the equivoque, it's quite difficult.  But there are some things that are generally agreed upon. First of all, by sweeping the ice you are putting energy into the ice. And so, you know that the important thing is that what govern the motion of the rock is what’s going on between the thing contact ring of the rock and the ice that it's touching¹¹. And you know, if you turn over curling rock and look at that,you notice that it is not the case that there is a circle in contact with the rock, it's a thin ring. And the ice itself is also not flat, it's pebbled¹² as little hills and valleys so that the actual area of contact is quite small and therefore there is a large pressure of the rock on the ice. Now in sweeping in front of the ice you are bringing the temperature to the ice, after that, it reduces the friction. But you are also creating a thin film of a quality liquid type of material. This is something that is not fully¹³ agreed upon by everybody, but the work that we've done strongly supports the idea that the key thing going on is the friction that is due to this thin liquid film. In fact, we did a number of experiments, Dr. Yangsen and I, with my colleagues at the university of Northern British Columbia. And we we did a number of experiments and then applied¹⁴ the theory that I had  developed, and we modified that theory, applied it and we could explain many things using the idea of there is a thin liquid film there, as opposed to that there is not a film there. So I'm very, I'm strongly convinced that there is a thing like a film there, and it plays a key role. With the liquid film you have better lubrication to the rock, and so you have less friction. And that's how the sweeping they could go further like this."

"And your most recent curling publication, you had, I think four that I found, is that right? How many scholarly papers on curling have you published?"

"Uh, more than I'd like to admit. It turns out that, you know, in  first studying to look at the problem. You anticipate so many interesting questions came up. And I don't actually remember how many I have published but it's something like eight, or something like that. But the one that is the most important in my opinion is the most recent paper that Dr. Yangsen and I collaborated¹⁵ on and published in the Canadian Journal of Physics in November of 2004."

"And that's the motion of curling rocks experimental investigation  in semi-phenomenon logical description."

"Exactly."