This volume gives an up-to-date, systematic account of the microscopic theory of Bose-condensed fluids developed since the late 1950s. In contrast to the usual phenomenological discussions of superfluid 4He, the present treatment is built on the pivotal role of the Bose broken symmetry and a Bose condensate. The many-body formalism is developed, with emphasis on the one- and two-particle Green's functions and their relation to the density response function. These are all coupled together by the Bose broken symmetry, which provides the basis for understanding the elementary excitations and response functions in the hydrodynamic and collisionless regions. It also explains the difference between excitations in the superfluid and normal phases. Chapter 4 gives the first critical assessment of the experimental evidence for a Bose condensate in liquid 4He, based on high-momentum neutron scattering data.
In the city of Midrash everything serves the military machine. Even the dragons - noble beasts whose world-view is governed by their honour - have been manipulated and deceived. They do not realise this will lead to their eventual extinction as a species. The Midrashi also kidnap children from other cities and force them into their army. When Seeger and Boyd become their latest victims, they struggle to maintain their humanity in this cruel and corrupt city. Will their friendship endure? Will they ever find their way home?