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Why does liquid helium creep up walls?

creep helium liquid walls
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Why does liquid helium creep up walls?

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A superfluid, such as liquid helium below 2.17 K, has no viscosity, unlike a normal fluid. This property is related to the condensate properties of liquid helium: in some sense, many of the atoms are in a single quantum state, like a “macro wavefunction”. It therefore takes a macroscopic amount of energy to promote any of the atoms to an excited state (they all have to get excited together). The superfluid therefore can’t lose energy to the walls of the container via the little friction-like bumps and kicks that cause viscosity in an ordinary liquid. So, the fluid flows with no viscosity. Normally, a viscous fluid in a container feels gravity, inter-molecule forces, and viscous forces from the walls of a container. If you eliminate viscous forces, the fluid feels only gravity and inter-molecule forces. Helium atoms in a container will be attracted to a thin film of helium already on the surface: this inter-molecule attraction exceeds the pull of gravity, and the molecules “siphon”

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