Emergent spacetime physics from quantum gravity

量子引力中的新兴时空物理学

• 批准号: 433545361
• 负责人: Dr. Daniele Oriti, Ph.D.
• 金额: --
• 依托单位: Arnold Sommerfeld Center for Theoretical Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/433545361?language=en
• 关键词: Emergent; spacetime; physics; quantum; gravity

The key question we want to address in this project is: “What is the effective macroscopic physics of fundamental quantum gravity models?”Quantum gravity is first and foremost a physical problem. Existing semi-classical models of early cosmology and black holes physics are fundamentally incomplete. For example, current cosmological scenarios (inflation, bouncing cosmologies, emergent universe scenarios) make assumptions about the initial state of the universe at the big bang or at high energy scales, or postulate new physics resolving the big bang singularity, that they cannot fully control. Only a theory of quantum gravity can justify these assumptions, modify such cosmological scenarios, or suggest new ones. Similarly, models of quantum black holes produce insights as well as puzzles that are unsolvable within semi-classical physics. Quantum gravity may also help to explain the indisputable successes of semi-classical physics in accounting for observations. This requires to connect solidly to GR and QFT, showing how their continuum structures (manifold, metric, matter fields) emerge from a fundamental theory.Accordingly, the main general objective of this project is the extraction of an approximate description of geometry and matter from quantum gravity models, identifying their observational signature, in the early universe and around black holes.The issues faced by quantum gravity approaches in this context are analogous to those faced routinely by condensed matter theorists (the extraction of macroscopic dynamics from the atomic description of a system). Inspired by this analogy, we explored the idea of spacetime as a condensate of quantum gravity (specifically, group field theory) building blocks; this early work is the basis of the present project.The project is constituted by two main directions, corresponding to the two physical contexts where we want to obtain observational consequences of fundamental quantum gravity models.Direction I: QG and fundamental cosmology The focus question of the first research direction of this project is:“What happened in the very early universe, beyond the regime described by semi-classical physics, and what are the physical signatures of its quantum gravity origin?”The main goal of this direction is to extract a detailed effective cosmological dynamics from microscopic quantum gravity models, capturing the physics of the early universe, and putting them in contact with observationsDirection II: QG and quantum black hole physicsThe focus question of the second research direction of this project is:“What is the quantum nature of black holes, responsible for their thermodynamic and information-processing properties? Can it be probed by gravitational waves observations?”The main goal of this direction is to use fundamental quantum gravity models to describe the microstructure and dynamics of black holes, how they store and process information and their thermodynamic properties.

我们要在这个项目中要解决的关键问题是：“基本量子重力模型的有效宏观物理是什么？”量子重力首先是物理问题。现有的早期宇宙学和黑洞物理学的半古典模型从根本上是不完整的。例如，当前的宇宙学场景（通货膨胀，弹跳宇宙学，新兴的宇宙场景）对大爆炸或高能尺度上的宇宙初始状态做出了假设，或者假设新物理学解决了大爆炸奇点，他们无法完全控制。只有量子引力理论才能证明这些假设合理，修改这种宇宙学场景或建议新的情况。同样，量子黑洞的模型产生了洞察力以及在半古典物理学中无法解决的难题。量子重力也可能有助于解释半古典物理学在观察中的无可争议的成功。这需要与GR和QFT保持牢固的联系，表明它们的持续结构（多种多样，度量，物质，物质领域）如何从基本理论中出来通常，通过凝结物质理论（从系统的原子描述中提取宏观动力学）。受这个类比的启发，我们探讨了时空作为量子重力（特别是小组田地理论）构建基块的凝结的想法。这项早期工作是本项目的基础。该项目由两个主要方向组织，与我们想要获得基本量子重力模型的观察性后果的两个物理环境相对应。方向I：QG和基本宇宙学的重点是该项目的第一个研究方向的重点问题：“除了在物理上所描述的范围，范围是什么，除了半范围内发生了什么范围的范围。这个方向的主要目标是从微观量子重力模型中提取详细的有效宇宙学动力学，捕获早期宇宙的物理学，并使它们与观察方向II：QG和量子黑洞物理学的焦点，该项目的第二个研究方向是：波浪观测？”这个方向的主要目标是使用基本的量子重力模型来描述黑洞的微观结构和动力学，它们如何存储和过程信息以及热力学特性。