Dynamics and Symmetry in Quantum Gravity

量子引力的动力学和对称性

• 批准号: 1806290
• 负责人: Jonathan Engle
• 金额: $ 18万
• 依托单位: Florida Atlantic University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-15 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806290&HistoricalAwards=false
• 关键词: Dynamics; Symmetry; Quantum; Gravity

An important question facing fundamental physics is how the well-tested laws of Einstein's theory of gravity and quantum mechanics are consistent -- the question of quantum gravity. This question is central for understanding the very origin of our universe, the big bang. Remarkable progress in understanding the big bang has occurred through the use of loop quantum cosmology (LQC), a simplified version of loop quantum gravity (LQG) for modeling the universe as a whole. This award seeks to bridge the gap between LQC and full LQG. Such a bridge would allow future comparisons of LQC with data to tell us exact details about the fundamental laws of quantum gravity. Bridging this gap requires answering a number of interesting fundamental conceptual questions. A second part of this research aims to answer key questions regarding the Feynman sum-over-histories formulation of loop quantum gravity, in which space and time are treated in a more unified way, and to bring this formulation closer to completion. By enabling graduate students to participate in frontier physics, and to interact with other research groups, this award will have a broad and long-term impact on the development of future scientists. The results of the research will be disseminated to the scientific community through peer reviewed publication and scientific lectures, as well as to the general public through public lectures and other means.With this award, the observational, cosmological consequences of different proposals for dynamics in LQG will be studied. To accomplish this, the PI will first find an embedding of LQC states into diffeomorphism invariant LQG states that satisfy the diffeomorphism invariant, quantum criterion for homogeneity and isotropy recently established by the PI's group. This embedding, appropriately regularized, will enable different proposals for dynamics in LQG to be translated into LQC, and thereby to distinguish their observational consequences using established methods. The task of finding the corresponding LQC dynamics will be simplified by the fact that the resulting possibilities are severely restricted by diffeomorphism invariance, as proven recently by the PI's group. The PI also plans to further develop the sum over histories approach to LQG, known as spin-foams. In prior work of the PI, the prevailing EPRL model of spin-foams was modified to correct its semiclassical limit, yielding what is called the proper spin-foam model. Since then, other research groups have indicated how this modified model may solve a number of long-standing issues in spin-foams. These possibilities, as well as other issues in spin-foams, will be investigated with the present award.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.

基本物理学面临的一个重要问题是爱因斯坦重力和量子力学理论的经过良好测试的定律是一致的 - 量子重力的问题。这个问题对于理解我们宇宙的起源是大爆炸是核心。 通过使用环量子宇宙学（LQC），这是理解大爆炸的显着进步，这是一种简化的环路量子重力（LQG），用于整体建模宇宙。 该奖项旨在弥合LQC和Full LQG之间的差距。 这样的桥梁将使LQC与数据的未来比较告诉我们有关量子重力基本定律的确切详细信息。弥合此差距需要回答许多有趣的基本概念问题。 这项研究的第二部分旨在回答有关循环量子重力的Feynman Sum-Or-Mo-Erover的关键问题，在此过程中，以更统一的方式对待时间和时间，并使此配方更接近完成。通过使研究生能够参与边境物理学并与其他研究小组进行互动，该奖项将对未来科学家的发展产生广泛的长期影响。该研究的结果将通过同行审查的出版和科学讲座以及通过公开讲座和其他手段向科学界传播给科学界。将研究该奖项，即在LQG中对不同提议的观察性，宇宙学的后果。 为此，PI首先将LQC状态嵌入到差异不变的LQG状态中，该状态满足PI组最近建立的均质性和同型的差异性，量子标准。适当正则化的这种嵌入将使LQG中动态的不同建议转化为LQC，从而使用既定方法来区分其观察性后果。通过PI组最近证明，找到相应的LQC动力学的任务将通过以下事实来简化以下事实。 PI还计划进一步开发有关LQG的历史方法的总和，称为自旋泡沫。 在PI的先前工作中，对旋转泡沫的流行EPRL模型进行了修改以校正其半经典极限，从而得出所谓的适当的自旋FOAM模型。从那以后，其他研究小组指出了该修改模型如何解决自旋泡沫中的许多长期问题。 这些可能性以及旋转泡沫中的其他问题将通过本奖项进行调查。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估标准通过评估来支持的。

项目成果

Quantum isotropy and the reduction of dynamics in Bianchi I

• DOI: 10.1088/1361-6382/ac337c
• 发表时间: 2021-02
• 期刊: Classical and Quantum Gravity
• 影响因子: 3.5
• 作者: C. Beetle;J. Engle;M. Hogan;P. Mendonca

The accidental flatness constraint does not mean a wrong classical limit

• DOI: 10.1088/1361-6382/ac655e
• 发表时间: 2021-11
• 期刊: Classical and Quantum Gravity
• 影响因子: 3.5
• 作者: J. Engle;C. Rovelli

Addendum to ‘EPRL/FK asymptotics and the flatness problem’

附录“EPRL/FK 渐进性和平坦度问题”

• DOI: 10.1088/1361-6382/abf897
• 发表时间: 2021
• 期刊: Classical and Quantum Gravity
• 影响因子: 3.5
• 作者: Engle, J;Kaminski, W;Oliveira, J
• 通讯作者: Oliveira, J

Entanglement entropy of Bell-network states in loop quantum gravity: Analytical and numerical results

圈量子引力中贝尔网络态的纠缠熵：分析和数值结果

• DOI: 10.1103/physrevd.99.086013
• 发表时间: 2019
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Bianchi, Eugenio;Donà, Pietro;Vilensky, Ilya
• 通讯作者: Vilensky, Ilya

Deriving loop quantum cosmology dynamics from diffeomorphism invariance

• DOI: 10.1103/physrevd.98.023505
• 发表时间: 2018-02
• 期刊: Physical Review D
• 影响因子: 5
• 作者: J. Engle;Ilya Vilensky