Expt 6) Superfluidity in 4He

In 1938, Pyotr Kapitza and, independently, John F. Allen and Don Misener demonstrated that on cooling below the “lambda temperature”, the viscosity of liquid 4He suddenly reduced by orders of magnitude. Kaptiza coined the name “superfluidity” in his famous paper, where he also presciently compared superfluidity to superconductivity. He used a rather ingenious experimental setup where the liquid flowed between two disks spaced about half a micron apart. By showing that the liquid helium in the...