"The reason we can gracefully glide on an ice-skating rink or clumsily slip on an icy sidewalk is that the surface of ice is coated by a thin watery layer. Scientists generally agree that this lubricating, liquidlike layer is what makes ice slippery. They disagree, though, about why the layer forms. Three main theories about the phenomenon have been debated over the past two centuries."
"In the mid-1800s, an English engineer named James Thomson suggested that when we step on ice, the pressure we exert melts its surface, making it slippery. Under normal conditions, ice melts when the temperature rises to 0 degrees Celsius (32 degrees Fahrenheit). But pressure lowers its melting point, so that even at lower temperatures, a layer of water might form on the surface. This theoretical relationship between melting point and pressure was experimentally confirmed by Thomson's younger brother William, better known as Lord Kelvin."
A thin, liquidlike layer coats the surface of ice and provides lubrication that makes ice slippery. Scientists generally agree on the existence of this watery surface layer but disagree on the mechanism that creates it. Three main hypotheses have been debated for two centuries, and researchers in Germany proposed a fourth hypothesis last year; no consensus has been reached. Hypothesis one (pressure melting) posits that pressure lowers ice's melting point; Lord Kelvin experimentally confirmed the pressure–melting point relationship. Bowden and Hughes argued that ordinary skiers exert too little pressure to melt ice. Hypothesis two attributes the layer to heat generated by friction; experiments in an artificial ice cave found higher friction with heat-conducting materials like brass.
Read at WIRED
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