The Great Ice-Skating Competition!

What's the Real Science Behind Skating?

Skating is a simple activity. So the science behind the sport must be simple, too, right? Wrong!

In fact, scientists have been arguing for over a hundred years about the precise science that allows us to skate. Now there's a new study, using technology designed for the space program. The result? Everything we thought we knew about the science of skating turns out to be wrong!

For a long time, experts theorized that the key to skating was pressure. Maybe the weight of the skater balancing on those thin blades produced enough pressure to melt the ice—leaving a thin film of water that helped the skater slide. True? Well, ice really does melt when it's placed under enough pressure—even when its temperature is below 0 degrees C (32 degrees F).

But then someone finally measured the pressure between a skate blade and the ice. It wasn't nearly enough to produce melting. So despite being quoted since the 1800s (and still appearing in some of today's science books), the “pressure” theory about ice-skating turns out to be wrong.

Another theory about skating involves friction. Like rubbing your hands together, friction can generate heat from motion. Does friction help a skater melt the ice?

Well, get ready for skating's newest spin. Seems that friction and even pressure do help us skate, in some ways. But the real secret behind skating is only discovered using the remarkable science of surface physics. That science is unlocking an amazing new world within ice, which exists only in the molecules right at the surface.

When scientists at Lawrence Berkeley National Laboratory trained high-tech instruments on this incredibly thin slice of the cold stuff, they encountered a bizarre new ice region. They call it “the quasi-fluid layer.” Compared to ordinary ice, half the molecules in the quasi-fluid layer appear to vanish. Actually, they're vibrating up and down at incredible speeds. No need to melt it; a natural quasi-fluid layer just a molecule thick makes even rock-solid ice slippery—even at minus 200 degrees C (minus 392 degrees F).

Forming a microscopic boundary between the ice and the surrounding air, this quasi-fluid layer is literally “on the edge.” Here, ice crystals “crush” inward from the force of a skater's blades. Normal water molecules deform into weird geometries; they lack “neighboring” molecules to hold them in shape. It's ordinary ice like you've never imagined it before.

This strange quasi-fluid layer is what makes ice-skating possible. In fact, heating or cooling the ice actually “engineers” the layer, producing lightning-fast ice for hockey, or the more “precise” ice that figure skaters use to win the gold.

With this new knowledge, the science of skating is changing at Olympic speed. No surprise; scientists are always challenging old theories so that they can discover new and more accurate explanations about our world. It's like knocking down a snowman so that you can build an even better one.

Turns out that skating is easy—but it takes high-tech science to really understand how it's done. Next time you head for the rink or the pond, think about the quasi-fluid layer. It helps you skate because it's “on the edge.”


Vocabulary

engineer:
To achieve by skill or cleverness.

friction:
Force from rubbing.

physics:
A science that deals with matter and energy and includes light, motion, sound, heat, electricity, and force.

quasi-:
To some degree.

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Activity

  1. What is the quasi-fluid layer of ice? What effect does this layer have on ice?
  2. Draw a diagram of ice. Show the regular ice layer and the quasi-fluid layer of ice. For each layer, draw an enlargement that shows how the molecules in that layer are moving. You may want to include arrows. Label the parts of your diagram.