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slight melting needed for the thin water layer to glide on. This theory also has its detractors , who point to the simple observation that ice is slippery even when standing still on it.

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Hot Metal In theory, there should be a point on the thermometer when skating should be possible on any solid surface. As University of California– Berkeley theoretical chemistry professor David Limmer told Vox in 2018, all solids will form a thin liquid layer when they are close to their melting temperature. Take a substance like gallium, for example. Gallium is a metal with a very low melting point—just under 86°F (30°C). This means that, in theory, you could play hockey on a shiny, mirrorlike surface of gallium in a balmy 80°F (26.7°C) rink!

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A 2015 theory by German scientist Bo Persson expanded on the friction theory, suggesting that depending on the speed at which the skater is moving, the ice will either melt or refreeze. The surface becomes one consisting of a substance that is switching between

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water and ice very rapidly. This still does not address the issue of why ice is slippery in the absence of friction, however. Perhaps it is because ice is just naturally slippery or, in other words, has very low friction. The science behind this theory (put forth by a team of Dutch researchers in 2018) argues that two types of water molecules exist on the

Ice is naturally slippery because rapidly moving water molecules keep its surface layer in a liquid state.

surface of ice. They studied the surface layer using a new technique known as sum frequency generation spectroscopy. Using lasers to

CHAPTER 1 : SKATING

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