Quantum Gravity, Horizons, and Beyond

该补助金将支持引力物理学的几个方面的研究项目，其中弯曲时空起着关键作用。其中一组主题涉及到理解时空的量子性质这一悬而未决的基本问题。具体而言，将根据时空量子态的性质进行研究。这项工作的大部分集中在事件视界的特殊作用上，因为它被认为是量子引力奥秘的一个有希望的窗口。其他工作将通过探索爱因斯坦引力理论的某些修改的理论和观测结果，特别是影响黑洞行为的结果，来探索爱因斯坦引力理论的有效性。该研究的另一个组成部分将解决有关中子星和黑洞等天体周围磁化等离子体行为的问题，并考虑到弯曲时空的影响。这项工作可有助于更好地了解射电望远镜对这些物体及其周围环境的观测。最后，与实验原子量子流体研究小组合作，研究将致力于探索和利用量子流体物理学与弯曲时空中的场之间的类比，例如在膨胀的宇宙中。拟议研究的结果将通过书面文章以及研讨会、会议会谈和座谈会传播，并将有助于我们对基本问题的理解，以及以更跨学科的方式进行观察和实验。PI将为研究生和本科生提供指导和指导，涉及科学研究，写作和口头交流。PI将在马里兰州大学为9年级学生和对物理感兴趣的高中女生设计和实施暑期课程。所有这些活动都将有助于技术培训和科学素养，以及对物理学见解的理解和欣赏。1）计算量子引力系综视界熵的路径积分方法，2）2+1维引力紧致域的非微扰约化相空间量子化，3）黑洞出射模的起源，4）玻色-爱因斯坦凝聚体中的模拟量子场论; 5）黑洞和中子星周围磁螺旋度的广义相对论处理; 6）洛伦兹破坏引力理论中的黑洞视界。在1）项下，一个项目将研究非微扰路径积分方法与最近使用代数量子场论的半经典分析之间的关系，另一个项目将询问近视界虚时演化方法在计算视界熵中的作用，否则将使用真实的时空路径积分。在2）下，目的是进一步理解先前发现的代数量子化中的算符和态，包括它们对熵和哈密顿量（时间演化）的影响。一种方法，这将是确定的关系，替代，协变相空间的方法，和所谓的角落对称代数，在这方面已经做了大量的工作，由他人。此外，我们可以扩展处理，以允许在空间域中的锥形奇点，手柄，或黑洞。根据3），将试图提高对引力异常和霍金辐射之间关系的理解，以及它与传出黑洞模式起源之谜的联系。此外，还将尝试使用微扰量子引力来表征点之间相关性的预期淬灭，其中一个点靠近视界。项目4）将与马里兰州玻色-爱因斯坦凝聚态小组合作，设计和解释量子化声子场的模拟量子场论测量。5）项下的项目将阐述理想等离子体中固定磁螺旋度时能量最小化的广义相对论理论，以及黑洞和中子星等边界允许螺旋度注入的域中的相对螺旋度理论。6）项下的项目将利用非稳态视界发生器探索黑洞视界的性质，以更好地了解视界结构及其曲率奇点在无限过去或未来的可能性。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The grant will support research projects on several aspects of gravitational physics where curved spacetime plays a key role. One group of topics pertains to the outstanding fundamental problem of understanding the quantum nature of spacetime. Specifically, research will be carried out pursuant to the nature of quantum states of spacetime. Much of this work focuses on the peculiar role of event horizons, since that is thought to be a promising window on the mysteries of quantum gravity. Other work will be directed at probing the validity of Einstein's theory of gravity by exploring the theoretical and observational consequences of certain modifications of that theory, particularly as that affects the behavior of black holes. A different component of the research will address questions about the behavior of magnetized plasma around astrophysical bodies like neutron stars and black holes, taking into account the effects of curved spacetime. This work could contribute to a better understanding of observations of these objects and their surroundings made with radio telescopes. Finally, in collaboration with an experimental atomic quantum fluid research group, research will be directed at exploring and exploiting the analogy between physics of quantum fluids and fields in curved spacetime, such as in the expanding universe. The results of the proposed research will be disseminated through written articles, as well as seminars, conference talks, and colloquia, and will contribute to our understanding of fundamental questions, as well as to observations and experiments in a more interdisciplinary fashion. The PI will provide instruction and mentoring to graduate and undergraduate students, regarding scientific research, writing, and verbal communication. The PI will design and implement instruction in a University of Maryland summer programs for rising 9th graders and for high school girls interested in physics. All of these activities will contribute to technical training and scientific literacy, as well as understanding and appreciation of the insights of physics.The main areas of work concern: 1) path integral methods for computing horizon entropy in quantum gravity ensembles, 2) non-perturbative reducedphase space quantization of a compact domain in 2+1-dimensional gravity, 3) the origin of outgoing black hole modes, 4) analog quantum field theory in a Bose-Einstein condensate, 5) general relativistic treatment of magnetic helicity around black holes and neutron stars, and 6) black hole horizons in Lorentz-violating gravity theories. Under 1), one project will study the relation between the nonperturbative path integral approach and the recent semiclassical analysis using algebraic quantum field theory, and another will interrogate the role of the near-horizon imaginary time evolution method in computing horizon entropy with an otherwise real spacetime path integral. Under 2) the aim is to further understand the operators and states in the algebraic quantization found previously, including their implications for entropy and Hamiltonian (time evolution). One approach to this will be to determine the relation to the alternative, covariant phase space approach, and to the so-called corner symmetry algebra, on which much work has been done by others. Further, we may extend the treatment to allow for conical singularities, handles, or a black hole in the spatial domain. Under 3) an attempt will be made to improve understanding of the relation between gravitational anomalies and Hawking radiation, and its connection to the puzzle of the origin of the outgoing black hole modes. Additionally, an attempt will be made to use perturbative quantum gravity to characterize the expected quenching of correlations between points, one of which is near a horizon. Projects under 4) will design and interpret analog quantum field theory measurements of the quantized phonon field, working together with the Maryland Bose-Einstein condensate group. Projects under 5) will formulate the general relativistic theory of energy minimization at fixed magnetic helicity in ideal plasmas, as well as of relative helicity in domains like black holes and neutron stars with boundaries allowing for helicity injection. Projects under 6) will probe the nature of black hole horizons with non-stationary horizon generators, to better understand how the horizon structure and the possibility of its curvature singularities in the infinite past or future.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.