Decoherence in quantum cosmology

摘要: We discuss the manner in which gravitational field becomes classical quantum cosmology. This involves two steps. First, one must show that state of strongly peaked about a set configurations. Second, system is number states relatively permanent nature have negligible interference with each other. second step decoherence---destruction off-diagonal terms density matrix, representing interference. To introduce notion decoherence, we it context theory measurement, following environment-induced superselection approach Zurek. then go on to application these ideas show, simple homogeneous isotropic model, matrix Universe will decohere if long-wavelength modes an inhomogeneous massless scalar are traced out. These effectively act as environment continuously ''monitors'' scale factor. The coherence width very small except neighborhood bounce. means cannot really say solution bounces because spacetime does not apply. coherencemore » decreases factor increases, has implications for arrow time. also using decoherence arguments, WKB component wave function represents expanding universes collapsing component. justifies usual assumption they may be treated separately.« less