Friday, June 12, 2009

Superfluidity

Sascha Grant points out this video of superfluidity. Superfluidity is a weird thing that happens when you bring liquid helium below 4 K. It can do strange things like climb glass (it has no viscosity) and leak through ceramic beakers. It has zero viscosity, zero entropy, and infinite thermal conductivity. It conducts heat in sound-like waves that move at 20mps at 1.8 K, a phenomenon known as second sound. The thin films, called Rollin films, that can climb glass display waves known as third sound. They act like ocean waves, except that the restoring force is not gravity but the Van der Waals attraction.

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