Midisuperspace laboratories for the dynamics of loop quantum gravity

对黑洞如何蒸发的研究可能是当今理论物理学中最重要的突出问题。它的解决方案需要理解现代物理学的两大支柱——引力和量子场论——在它们最极端的状态下的行为。在过去，理解物理理论如何在具有挑战性的制度中融合在一起，会带来惊人的结果。一个例子是麦克斯韦对电和磁如何结合在一起的理解，这种综合导致了无线电波的发现，以及随之而来的社会变革。这类工作的第二个非常重要的目标是形成高质量的人力资源。在这些学科中接受训练的物理学家已经在工业、金融以及科学领域做出了贡献。该小组将研究环量子引力技术在球对称环境中的应用，最终目标是理解黑洞蒸发。他们将研究他们在之前的项目中开发的球对称量子时空上的量子场的反反应。量子时空的离散性自然地使量子场论的无限性正则化，使所有结果都是有限的。要研究反向反应，需要比我们目前拥有的更现实的量子时空，包括动态进化。他们建议找到一个坍塌壳的量子时空，并计算其上的场的反反应。除此之外，他们还建议研究我们目前所拥有的量子时空的结构，特别是在极值和超极值带电黑洞的情况下的奇点结构，以及在解中出现的柯西视界。他们还建议将均匀离散化作为一种量化方法继续研究，特别是与用于构建球形量子时空的精确量子化进行比较，后者依赖于约束代数的阿贝尔化，这是一种人们不希望推广到更复杂模型的条件。他们还将探讨一个关于时间问题的建议，以及随后解决量子力学中测量问题的建议。他们希望探索比目前所建立的模型更普遍的模型，并研究强涌现问题。

The study of how black holes evaporate is perhaps the most important outstanding problem in theoretical physics today. Its solution requires understanding the behavior of two of the pillars of modern physics, gravity and quantum field theory, in their most extreme regimes. Understanding how physical theories fit together in challenging regimes has in the past led to insights of spectacular consequences. An example of this could be Maxwell's understanding of how electricity and magnetism fit together, a synthesis that led to the discovery of radio waves, with the ensuing transformational changes they induced in our society. A second very important objective of this type of work is the formation of human resources of very high quality. Physicists trained in these disciplines have moved on to make contributions leading to rewarding careers in industry and in finance, as well as science.The group will study the application of techniques of loop quantum gravity in spherically symmetric contexts with the ultimate goal of understanding black hole evaporation. They will study the back-reaction of quantum fields living on spherically symmetric quantum space-times that they developed in a previous project. The discreteness of the quantum space-time naturally regularizes the infinities of quantum field theory yielding all results finite. To study the back reaction will require quantum space-times more realistic than the ones we have up to now, including dynamical evolution. They propose to find the quantum space-time of a collapsing shell and compute the back reaction of fields living on it. In addition to this they propose studying the structure of the quantum space-times we have up to now, in particular their singularity structure in the case of extremal and super extremal charged black holes and the Cauchy horizons that appear in the solutions. They also propose to continue the study of uniform discretizations as a quantization approach, in particular comparing with the exact quantization that was used to construct the spherical quantum space-times, which relied on the Abelianization of the algebra of constraints, a condition that one does not expect to generalize for more complex models. They will also explore a proposal for the problem of time and an ensuing proposal for solving the measurement problem in quantum mechanics. They wish to explore more general models than the ones worked out up to now and to study the issue of strong emergence.