Classical and Quantum Gravitation and Cosmology

这个小组将在引力和天体物理学方面进行广泛的研究。 需要调查的专题如下： 1)与非欧拓扑学相关的量子引力的方面将被检查。 我们将在渐近平坦时空和具有卡鲁扎-克莱因对称性的时空中考虑具有非欧拓扑的定态的可能存在性。 将考虑量化的补充方法。 2)在量子场和引力领域，研究包括调查量子电动力学异常对膨胀宇宙中费米子能量密度的影响。 研究中还包括对广义相对论流体球度规的量子修正、黑洞蒸发中信息和相关性的可能损失以及早期宇宙中的相对论玻色-爱因斯坦凝聚。 3)早期宇宙中的奇异过程，例如宇宙弦网络的形成，以及快速膨胀对量子涨落的放大，都会留下引力波的随机背景。 将进行详细的研究，以确定这些波的可观测特性，它们对宇宙背景辐射各向同性的影响，以及它们通过地面和空间引力波天线的可探测性。 4)广义相对论天体物理学的研究将包括建立一个计算理想流体非轴对称不稳定点的代码。 将与开发相对论3+1代码的工作人员合作，研究不稳定恒星的非线性动力学演化。 其他的工作将涉及到独立于状态方程的旋转上限的确定。 这些主题在探索现代引力理论的基础，并将其与可能的天文观测联系起来方面具有很高的兴趣。

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.