What better time to talk about some of the science of ice skating than during the Winter Olympics.

It's commonly believed that you can skate on ice because the pressure of the blades melts the ice, forming a thin layer of water that makes it slick. Friction between the skates and the ice also creates a little heat, which helps in the melting. It turns out, however, that these two processes can't account for all aspects of ice's slipperyness, such as why it's slick even at very low temperatures and why it's tricky to even stand still on ice.

To get at the rest of the explanation, we need to zoom down to the molecular scale. Deep inside a layer of ice, molecules are bonded to each other in a very organized way. But near the ice's surface, the bonding isn't as rigid, simply because the air above the ice means that the water molecules don't have as many neighbors to bond to. These "freer" water molecules near the ice surface form a natural, ultra-thin liquid-like layer. This phenomenon is known as "surface melting," and it helps make ice slippery, whether anybody's skating on it or not.