Theoretical Investigations in Classical and Quantum Gravity

这个项目的目标是在引力物理学的几个领域做出重大贡献。主题范围从理解引力波探测器（如美国国家科学基金会的激光干涉引力波天文台（LIGO）和欧洲处女座）观测到的信号，到研究黑洞的本质和宇宙的起源。与过去由美国国家科学基金会资助的研究一样，这些结果很可能成为跨学科会议的亮点，加强不同社区之间的交流。这项资助的研究也将增加STEM学科的人力资源，因为博士后和学生将获得各种技能，包括先进的计算和建模技术。这项拨款支持的研究将涵盖以下主要主题：(i)引力波。LIGO最近的发现为研究宇宙打开了一扇全新的窗口。拟议研究中的第一批项目将为引力波的产生和传播奠定基础，这些引力波是在我们所居住的充满暗能量的加速宇宙的现实背景下产生和传播的。（ii）第二组项目将侧重于黑洞的量子力学特性。在广义相对论的经典世界里，黑洞是物质、能量和信息的汇聚点。但是它们通过发射量子辐射而蒸发。人们普遍认为能量在这个过程中是守恒的，但关于信息是否仍然丢失，或者是否在发射的量子辐射中完全编码，一直存在争论。这项正在进行的NSF资助支持的先前工作强烈表明，量子引力效应将消除黑洞中心的“奇点”，从而为似乎丢失在那里的信息的出现扫清道路。这一过程的细节将会制定出来。第三个项目涉及非常早期的宇宙。在目前公认的宇宙学范式中，量子物理学在宇宙的早期阶段是不可或缺的，然而，不久之后，人们就习惯地假设宇宙的行为是经典的，就像广义相对论一样。这种经典行为是如何出现的，以及为什么量子物理学的所有微妙和复杂都可以被忽略，这些都是基于基础原因和将理论与观测联系起来的非常有趣的问题。我们将结合弯曲时空中的量子场论、控制早期宇宙动力学的方程和量子力学的几何公式来解决这些问题。（iv）上述三个项目都是从事哲学和物理科学前沿，特别是广义相对论、宇宙学和量子物理学交叉研究的研究人员非常感兴趣的。研究结果将在这些领域的会议和研讨会上进行讨论，并用于培训这两个学科的年轻科学家和哲学家。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will aim at making significant contributions to several areas within gravitational physics. The topics range from understanding the signals observed by gravitational wave detectors such as NSF's Laser Interferometric Gravitational Wave Observatory (LIGO) and the European Virgo, to studying the nature of black holes and the origin of the Universe. As with the past research supported by ongoing NSF grants, these results are likely to feature as highlights in interdisciplinary conferences, enhancing communication between diverse communities. Research funded by this grant will also add to human resources in STEM disciplines since post-docs and students will acquire diverse skills, including advanced computational and modeling techniques.Research supported by this grant will cover the following main themes: (i) Gravitational waves. Recent discoveries at LIGO have opened a brand new window on the universe. The first set of projects in the proposed research will lay down foundations for production and propagation of gravitational waves in the realistic context of the accelerating universe with dark energy, which we inhabit. (ii) A second set of projects will focus on quantum mechanical properties of black holes. In the classical world of general relativity, black holes are sinks of matter, energy and information. But they evaporate through emission of quantum radiation. There is a general agreement that energy is conserved in this process but there has been an ongoing debate on whether information is still lost, or if it is fully encoded in the quantum radiation that is emitted. Previous work supported by this ongoing NSF grant strongly suggests that quantum gravity effects will remove the `singularity' at the center of the black hole, thereby clearing the way for information --that appeared to be lost there-- to come out. Details of this process will be worked out. (iii) The third project involves the very early universe. In the currently accepted cosmological paradigms, quantum physics is indispensable in the very early phase of the universe, and yet, soon thereafter it is customary to assume that the universe behaves classically, as in general relativity. How this classical behavior can emerge, and why all the subtleties and intricacies of quantum physics can be ignored, are issues of great interest both for foundational reasons and for bridging theory with observations. They will be addressed using a combination of methods from quantum field theory in curved space-times, equations governing dynamics of the early universe and geometric formulation of quantum mechanics. (iv) All three projects discussed above are of deep interest to researchers working at the interface of philosophy and frontiers of physical science, particularly general relativity, cosmology and quantum physics. The results will be discussed at conferences and workshops in these fields, and serve to train young scientists and philosophers in both disciplines.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.