Modern low-temperature physics began with the liquefaction of helium by Kamerlingh Onnes (1908) and the discovery of superconductivity (Kamerlingh Onnes, 1911) at the University of Leiden in the early part of the 20th century. There were really two surprises that came out of this early work. One was that essentially all of the electrical resistance of metals like mercury, lead, and tin abruptly...

In this paper we develop a general theory of the spin dynamics of anisotropic Fermi superfluids of the generalized BCS type, under conditions which should be realistic for any such phase of liquid 3He occurring below 3 mK. No restrictions are placed on the nature of the pairing configuration. The system is described in terms of the total spin vector S, and a vector T(n) which describes the ampl...