Probing the quantum gravitational structure of spacetime via black holes and gravitational waves

通过黑洞和引力波探测时空的量子引力结构

• 批准号: RGPIN-2021-03644
• 负责人: Rastgoo, Saeed
• 金额: $ 1.75万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763072
• 关键词: Probing; quantum; gravitational; structure; spacetime

The two fundamental pillars of modern physics are General Relativity (GR) and Quantum Field Theory (QFT). GR describes classical spacetime and phenomena in which gravity is very strong. QFT describes quantum phenomena and physics at small scales. Phenomena in which both gravitational and quantum effects are significant cannot be studied using either of these theories alone and require a certain consistent combination of GR and QFT. This combination is a theory under development called Quantum Gravity (QG). Full development of this theory has proven to be very challenging. Once completed, QG is expected to provide us with a detailed knowledge of the most fundamental aspects of the Universe, particularly, the quantum structure of spacetime. Knowledge gained about this structure will answer many important questions, including the dynamics of the interior of quantum black holes, the nature of their singularities, and the behavior of nature at the quantum epoch of cosmology. Finding a full theory of QG is considered to be the final goal of modern physics. The long-term goal of my research program is to make significant contributions toward finding a full theory of QG. I will use several short-term goals to achieve this objective. Part of these goals center around studying various obstacles in combining GR and QFT and providing resolutions for them. As previously noted, the obstacles are deeply related to the fundamental nature of spacetime. An important question I will try to answer is "how does spacetime look in very small (quantum) scales?" Another longstanding issue is "how does quantum spacetime become the classical spacetime at larger scales?" To provide answers to these questions, I will search for important hints about the nature of spacetime from both theory and phenomenology. I will use two main natural laboratories: black holes and Gravitational Waves (GWs)/Gamma Ray Bursts (GRBs). Black holes are one of the most important playgrounds of QG. I will study quantum black holes and their interactions with matter fields to find important deviations from classical physics rooted in QG. This study will also serve as a standalone investigation into quantum black holes. GWs and GRBs travel from their source over cosmological distances before being detected by instruments such as the Laser Interferometer Gravitational-wave Observatory (LIGO.) If spacetime has a quantum fine structure, it will imprint certain signatures on these waves that can be observed by experiments. I will investigate and derive these signatures and compare them with LIGO observations to obtain valuable information about both the nature of QG and spacetime. This also serves towards bridging the gap that currently exists between QG theory and experiment. My proposed research will make a significant contribution to the full development of QG which is of major importance to modern physics. It will also raise the profile of Canadian scientific contribution in this area.

现代物理学的两个基本支柱是广义相对论（GR）和量子场论（QFT）。广义相对论描述了经典时空和引力非常强的现象。QFT描述了小尺度上的量子现象和物理学。引力和量子效应都很重要的现象不能单独使用这两种理论中的任何一种来研究，需要GR和QFT的某种一致的组合。这种结合是一种正在发展的理论，称为量子引力（QG）。这一理论的全面发展已被证明是非常具有挑战性的。 一旦完成，QG有望为我们提供宇宙最基本方面的详细知识，特别是时空的量子结构。关于这种结构的知识将回答许多重要的问题，包括量子黑洞内部的动力学，奇点的性质，以及宇宙学量子时代的自然行为。找到QG的完整理论被认为是现代物理学的最终目标。 我的研究计划的长期目标是为找到QG的完整理论做出重大贡献。我将使用几个短期目标来实现这一目标。这些目标的一部分围绕着研究GR和QFT结合的各种障碍，并提供解决方案。如前所述，这些障碍与时空的基本性质密切相关。我将试图回答的一个重要问题是“时空在非常小的（量子）尺度上看起来如何？另一个长期存在的问题是“量子时空如何在更大尺度上成为经典时空？”为了回答这些问题，我将从理论和现象学两方面寻找关于时空本质的重要线索。我将使用两个主要的自然实验室：黑洞和引力波（GW）/伽马射线暴（GRB）。黑洞是QG最重要的游乐场之一。我将研究量子黑洞及其与物质场的相互作用，以发现与植根于QG的经典物理学的重要偏差。这项研究也将作为对量子黑洞的独立研究。GWs和GRBs从它们的源头经过宇宙学距离，然后被激光干涉仪引力波天文台（LIGO）等仪器探测到。如果时空具有量子精细结构，它将在这些波上留下某些可以通过实验观察到的特征。我将研究并推导出这些特征，并将它们与LIGO观测结果进行比较，以获得有关QG和时空性质的有价值的信息。这也有助于弥合QG理论和实验之间目前存在的差距。我提出的研究将为量子G的全面发展做出重大贡献，量子G对现代物理学具有重要意义。它还将提高加拿大在这一领域的科学贡献的形象。