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.
<i>Greek: A History of the Language and its Speakers, Second Edition</i> reveals the trajectory of the Greek language from the Mycenaean period of the second millennium BC to the current day. <p> • Offers a complete linguistic treatment of the history of the Greek language<br> • Updated second edition features increased coverage of the ancient evidence, as well as the roots and development of diglossia<br> • Includes maps that clearly illustrate the distribution of ancient dialects and the geographical spread of Greek in the early Middle Ages