Classical and Quantum Gravitation and Cosmology

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This group will pursue a broad program of research in gravitation and astrophysics. Among the topics to be investigated are the following: 1) Aspects of quantum gravity associated with noneuclidean topology will be examined. The possible existence of stationary states with noneuclidean topology will be considered in the context of asymptotically flat spacetimes and spacetimes with Kaluza-Klein symmetries. Complementary approaches to quantization will be considered. 2) In the area of quantum fields and gravitation, research includes an investigation of the effect of quantum electrodynamic anomalies on the energy density of fermions in the expanding universe. Also under study are quantum corrections to the metrics of general relativistic fluid spheres, the possible loss of information and correlations in black hole evaporation, and relativistic Bose-Einstein condensation in the early universe. 3) Exotic processes in the early universe, such as the formation of a network of cosmic strings, and the amplification of quantum fluctuations by rapid expansion, leave behind a stochastic background of gravitational waves. A detailed study will be pursued to determine the observable properties of these waves, their effects on the isotropy of the Cosmic Background Radiation, and their detectability by ground-and space-based gravitational wave antennae. 4) Research in general-relativistic astrophysics will include the construction of a code that computes the nonaxisymmetric instability points of perfect fluids. The nonlinear dynamical evolution of unstable stars will be examined in collaboration with workers developing a relativistic 3+1 code. Other work will involve the determination of an upper limit on rotation independent of the equation of state. These topics are of high interest in exploring the fundamentals of modern gravitation theory, and connecting it to possible astronomical observations.