VO: Have you ever wondered how ice skates run? Something to do with ice being slippery perhaps?
JONNY PHILLIPS: ell surprisingly it's not as simple as you might think and the exact mechanism behind how ice skates actually work has been hotly disputed for years.
VO: One theory is the heat generated by the friction of the skates moving on the ice produces a slippery film of water between the metal blades and the ice.
RICHARD AMBROSE: Tis sounds logical, but it doesn't explain why skates are still slippery even at a standstill.
VO: nother theory is it's the pressure of the skater's weight applied through the narrow metal blades that reduces the melting point of the ice, and again produces a slippery film to ride on.
JONNY PHILLIPS: nd its true pressure can reduce the melting point of ice, as this experiment will demonstrate.
JONNY PHILLIPS: o, we've got a block of ice, around which we're going to place this cheese wire, which is attached to some weights. Now watch this.
RICHARD AMBROSE: Now, just like the ice skates, the ice under the wire is put under tremendous pressure and this reduces the melting point of the ice. Its already starting to cut in there, it's amazing. Look at that.
JONNY PHILLIPS: s the wire passes through the ice above it refreezes as the pressure's released. It's incredible. How cool is that?
RICHARD AMBROSE: That is so cool.
VO: nd after a few more minutes, the wire was ready to drop.
RICHARD O it's working! Hey! Now look Jonny. One solid block of ice.
JONNY PHILLIPS: an you see that, can you see that frosted.,,
RICHARD AMBROSE: Where its cut through.
JONNY PHILLIPS: pane going through it.
RICHARD AMBROSE: That is excellent.
JONNY PHILLIPS: And that is still very, very...
RICHARD AMBROSE: Try and break it. You can't do it can you?
JONNY PHILLIPS: solid.
VO: nfortunately, this pressure theory doesn't provide the whole answer either. A typical skater only produces enough pressure to reduce the ice melting point by a few degrees, which would making skating at anything more than just below zero a bit tricky.
JONNY PHILLIPS: o what's the answer? Well the latest scientific thinking is that it's a combination of the pressure theory and the friction theory, along with the fact that the bonds that bind the ice molecules together are weaker near the surface.
RICHARD AMBROSE: So you mean after that, ice is naturally slippery?
JONNY PHILLIPS: Um, well yeah. Technically speaking