Research in Classical and Quantum Gravity

经典和量子引力研究

• 批准号: 2107939
• 负责人: Gary Horowitz
• 金额: $ 144万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2107939&HistoricalAwards=false
• 关键词: Research; Classical; Quantum; Gravity

This awards supports research in gravitational physics at the University of California, Santa Barbara. Many of the deepest problems in theoretical physics revolve around combining Einstein's theory of general relativity with quantum theory. The resulting theory is called "quantum gravity" and is needed to better understand the origin of the universe, the nature of space and time on small scales, and what happens inside black holes. The research supported by this grant will use the latest techniques and tools to try to answer some of these fundamental problems. An essential part of the work is the training of graduate students and postdoctoral researchers in the knowledge and techniques that are central to understanding and discovery in gravitational physics. Through a range of forums from public lectures, to informing media reporters, the Principal Investigators will disseminate the directions and results of their research to a broad audience. Society at large will benefit by increasing their understanding of science and the world they live in.The research involves three inter-related programs of research. The first works to understand what sort of spacetimes are needed to describe gravity at the quantum level, taking into account the quantum fluctuations that may range far beyond familiar classical solutions. In particular, the light-cone structure of such spacetimes may be far from classical, and may even be singular. We will investigate the implications of such effects for distant observers, focusing on properties called unitarity and boundary causality. And while it is now understood to be consistent to include fluctuations that cause the spacetime to change topology, the investigators will study whether fluctuations at this level are in fact required by fundamental principles. A second part of the project further investigates the physical consequences of fluctuating topology and the associated processes by which a large universe may interact with a physically-separate closed universe (often called a baby universe). It was shown recently that this at least partially resolves the nearly 50-year-old black hole information problem, but the actual physics experienced by an observer inside an old evaporating black hole remains to be fully understood. The project will also study associated implications for the above-mentioned closed universes, and thus for cosmology and for our universe as a whole. The final part probes the 50-year-old cosmic censorship hypothesis and the structure of singularities in classical gravity. Known violations of certain versions of cosmic censorship with AdS boundary conditions will be analyzed in more detail with an eye toward 1) connections to the so-called weak gravity conjecture of high energy physics and 2) developing possible further counter-examples in asymptotically flat spacetimes. The fact that certain black hole singularities show strong sensitivity to parameters will also be explored. The methods employed in all three programs of research will be primarily analytic, though these will be supplemented with numerical calculations on desktop computers.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.

该奖项支持加州大学圣巴巴拉分校的引力物理学研究。理论物理学中的许多最深层次的问题都围绕着爱因斯坦广义相对论与量子理论的结合。由此产生的理论被称为“量子引力”，需要更好地理解宇宙的起源、小尺度上的空间和时间的本质，以及黑洞内部发生的事情。这笔赠款支持的研究将使用最新的技术和工具来尝试回答其中一些基本问题。这项工作的一个重要部分是对研究生和博士后研究人员进行知识和技术的培训，这些知识和技术对于理解和发现引力物理学至关重要。通过公开讲座、新闻媒体记者等一系列论坛，首席研究员将向广大受众传播他们的研究方向和结果。整个社会将通过增加对科学和他们生活的世界的了解而受益。这项研究涉及三个相互关联的研究项目。第一个工作是了解在量子水平上描述引力需要什么样的时空，同时考虑到可能远远超出熟悉的经典解决方案范围的量子涨落。特别是，这种时空的光锥结构可能远非经典，甚至可能是奇异的。我们将研究这种效应对遥远观察者的影响，重点关注幺正性和边界因果关系的性质。虽然现在人们认为它是一致的，包括导致时空改变拓扑的涨落，但研究人员将研究这一水平的涨落实际上是否是基本原理所需要的。该项目的第二部分进一步研究波动拓扑的物理后果以及大宇宙可能与物理上独立的封闭宇宙（通常称为婴儿宇宙）相互作用的相关过程。最近的研究表明，这至少部分解决了近 50 年之久的黑洞信息问题，但观察者在古老的蒸发黑洞内所经历的实际物理现象仍有待完全理解。该项目还将研究对上述封闭宇宙的相关影响，从而对宇宙学和整个宇宙产生影响。最后一部分探讨了 50 年前的宇宙审查假说和经典引力奇点的结构。我们将更详细地分析已知违反某些 AdS 边界条件的宇宙审查制度，着眼于 1）与高能物理的所谓弱引力猜想的联系，以及 2）在渐进平坦时空中开发可能的进一步反例。还将探讨某些黑洞奇点对参数表现出强烈敏感性的事实。所有三个研究项目所采用的方法将主要是分析性的，尽管这些方法将辅以台式计算机上的数值计算。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。

项目成果

Novel supersymmetric extension of BMS symmetries at null infinity

BMS 对称性在零无穷远处的新颖超对称扩展

• DOI: 10.1103/physrevd.105.064054
• 发表时间: 2022
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Prabhu, Kartik

Gravitational thermodynamics without the conformal factor problem: partition functions and Euclidean saddles from Lorentzian path integrals

没有共形因子问题的引力热力学：配分函数和洛伦兹路径积分的欧几里德鞍点

• DOI: 10.1007/jhep07(2022)108
• 发表时间: 2022
• 期刊: Journal of High Energy Physics
• 影响因子: 5.4
• 作者: Marolf, Donald

Quantum Extremal Surfaces and the Holographic Entropy Cone

• DOI: 10.1007/jhep11(2021)177
• 发表时间: 2021-08
• 期刊: Journal of High Energy Physics
• 影响因子: 5.4
• 作者: C. Akers;Sergio Hernandez-Cuenca;Pratik Rath

Almost all extremal black holes in AdS are singular

AdS 中几乎所有极值黑洞都是奇异的

• DOI: 10.1007/jhep01(2023)162
• 发表时间: 2023
• 期刊: Journal of High Energy Physics
• 影响因子: 5.4
• 作者: Horowitz, Gary T.;Kolanowski, Maciej;Santos, Jorge E.
• 通讯作者: Santos, Jorge E.

Bouncing inside the horizon and scrambling delays

在地平线内弹跳和混乱的延迟

• DOI: 10.1007/jhep11(2022)025
• 发表时间: 2022
• 期刊: Journal of High Energy Physics
• 影响因子: 5.4
• 作者: Horowitz, Gary T.;Leung, Henry;Queimada, Leonel;Zhao, Ying
• 通讯作者: Zhao, Ying