Cutting Ice into One
Saturday, November 7, 2009
A Stranger-than-Friction 40th Anniversary Event

Imagine a big block of ice suspended from the ceiling of the Exploratorium. Now imagine a wire wrapped around the middle of that ice block from which is hung a motorcycle. Chill out with other skeptics and watch the motorcycle fall to the floor as the wire very slowly cuts through the ice, but bear witness—the ice block remains one whole piece! Check out this stranger-than-friction phenomenon for yourself at the Exploratorium’s Cutting Ice into One, on Saturday, November 7, 2009, during a free weekend as we continue celebrating our 40th anniversary.

This enigmatic sculpture, originally inspired by the work of local artist Art Grant, suggests the inexorable passage of time as the ice is gradually divided and then refreezes after the wire moves through it. In keeping with our celebration, using the motorcycle as a weight in this experiment was the idea of Exploratorium founder, Frank Oppenheimer.

How does the seemingly unpredictable ending—one chopper off the solid block—come about? What’s going on here? The wire is lying on the block of ice with the heavy weight of the motorcycle pulling it down. This large force applied over a very narrow wire will apply a lot of pressure to the ice, causing the small band of ice directly below the wire to melt. As the small layer of ice melts, the wire will move downward into the ice block, pushing the liquid water aside. The rub here is that the greater the applied pressure, the lower the melting point. Therefore, the melted water never appreciably changes temperature, and the water that is pushed aside no longer has pressure applied to it and so refreezes. This phenomenon, which physicists call regelation, continues layer by layer until the wire passes through the entire block and the block remains a solid frozen mass.

Check out http://www.exploratorium.edu/40th/

General admission to the Exploratorium on November 7th and 8th is free to the public, part of the Exploratorium’s 40th Anniversary Weekend celebration.  Admission to the Tactile Dome is discounted by 40% during the weekend.