Chemical properties of superfluid helium

Some unusual properties of He-II:

• The puzzle of its viscosity:
  • It flows through the finest capillaries with no apparent resistance
  • There is a finite drag of fluid in torsional experiments (Keesom, Andronikashvilli)
• Thermo-mechanical couplings:
  • No boiling bubbles
  • Heating of a pressurized compartment in the superflow experiment
  • The fountain effect

• Interactions: He-II is a practically incompressible liquid due to hard-core interactions, while the ideal BEC has no compressibility!
• Differences in the heat-capacity curves:
  • There is a λ-like logarithmic divergence in heat capacity, as opposed to the finite hump in BEC
  • Heat capacity vanishes as T^ at low temperatures, as opposed to T^ for BEC
  • The superfluid fraction not vanish linearly at the transition point
  • The normal fraction does not vanish as T^ at zero temperature
  • Colloquium (pdf) by Sebastien Balibar on the occasion of Lazlo Tisza's 100th birthday (1907-2009)
  • Movie on Superfluidity by Alfred Leitner (offline)

  8.333 Superfluid Helium