When a single beam-splitter receives two beams of bosons described by Fock states (Bose-Einstein condensates at very low temperatures), interesting generalizations of the two-photon Hong-Ou-Mandel effect take place for larger number of particles. The distributions of particles at two detectors behind the beam splitter can be understood as resulting from the combination of two effects, the spontaneous phase appearing during quantum measurement, and the quantum angle. The latter introduces quantum “population oscillations”, which can be seen as a generalized Hong-Ou-Mandel effect, (...) although they do not always correspond to even-odd oscillations. (shrink)

Contemplating the catastrophic course of the Nazi Revolution we may well find it all too easy to see nothing in the spectacle but the nether darkness made visible; and if we are advised that it is not merely permissible but highly advisable to learn from the enemy, we may be tempted to think that whatever the Nazi war-machine has to teach the strategist and the technician, the political history of Germany in the last decade, and in particular the political ideology (...) that has imposed itself upon the German mind with such apparent thoroughness, can yield only the negative lesson of a warning, by displaying upon the world-wide stage the doomful consequences of wrong principles ruthlessly pushed to their extreme. But it is certainly an error to deny that nothing of more positive value has emerged out of the revolutionary cauldron: and indeed it would be more than strange, where such whole-hearted energies of mind are being enlisted in the evil cause of Nazism, if none of its votaries had ever stumbled for a time into wisdom. (shrink)

Recently a growing number of biologists have begun to consider the causal role that processes of embryonic development may play in evolution. This constitutes a reunion of these phenomena which had been linked in the nineteenth century through Haeckel's biogenetic law. This reunion may result in a new subdiscipline of biology, if there is a set of unique concepts and methods which tie the various research approaches together. Such concepts as bauplan, canalization, and developmental constraint, may serve in such a (...) capacity. The methods employed must combine comparative and experimental analyses, with special attention paid to the range of variation in developmental events within each taxon. These concepts and methods are also applicable to the problem of how development evolved, thus the evolution of development may also be considered part of the reunion. The reunion is discussed in terms of the potential participation of various schools of thought found in the current literature. (shrink)