Quantum Theories of Gravity and Spacetime

理论引力物理学的研究涉及量子引力问题，主要是针对这样一个问题：“通常的时空连续体模型是否适合将量子物理和引力结合起来的理论，如果不合适，应该用什么来取代它？”Jacobson博士将研究这一课题的几个方面：1)将广义相对论中约束问题的部分解应用于引力量子化的标准配方；2)黑洞辐射与不同短距离时空结构假设的相容性；时变时空几何中截止量子场论的定义问题；4)因果网络的约束关系和允许的网络结构分类；5)封闭类时曲线在2 + 1维量子引力中的作用；6)在没有外部时间概念的情况下解释量子引力的形式主义的问题。

This research in theoretical gravitational physics concerns the problem of quantum gravity and is directed primarily at the question "is the usual continuum model of spacetime appropriate in a theory uniting quantum physics and gravitation and, if not, by what should it be replaced?" Several facets of this subject will be investigated by Dr. Jacobson: 1) application of the partial solution of the constraint problem in general relativity to the standard recipe for quantization of gravity; 2) the compatibility of black hole radiation with different assumptions about short distance spacetime structure; 3) the problem of defining cutoff quantum field theory in time-dependent spacetime geometries; 4) constraining relations in causal networks and classification of allowed network structures; 5) the role of closed timelike curves in 2 + 1 dimensional quantum gravity; 6) the problem of interpreting the formalism of quantum gravity in the absence of an external notion of time.