String Theory as Quantum Gravity IV

我的长期目标是理解如何调和爱因斯坦的引力理论与量子力学，特别是对黑洞物理学的兴趣。为了研究这一点，我使用弦理论，这是目前在量子引力物理学中进行感兴趣的计算的最好的理论框架。弦理论是一个合适的工具集，因为它设法涵盖了大尺度上引力的光滑时空几何和小尺度上量子力学的概率不确定性。在过去的19年里，弦理论技术的两个相关进展帮助我实现了长期目标。 第一个进展是发现了更高维的物体，在弦论中被称为D膜，它与一维基本弦共存。D-膜是多才多艺的理论动物，因为它们有引力并带有电荷。应用很快就被发现，为长期存在的黑洞物理学基本问题提供了新的线索。例如，弦技术应用于各种特殊的高维黑洞，使得第一次从贝肯斯坦-霍金熵的第一原理定量推导成为可能，这是一个类似于无序的量，它编码了黑洞在引力坍缩中形成的大量方式。具有许多运动部分的弦理论模型也有可能解决另一个更复杂的问题：霍金著名的黑洞信息悖论，它涉及福尔斯落入黑洞的信息的命运。已经取得了很大进展，但仍有更多领域有待了解。进一步发展黑洞物理学的微观弦理论模型是这项研究计划的两个主题之一。 第二个进展是一个令人惊讶和强大的新发现，某些具有负宇宙常数的引力理论拥有一个额外的空间维度，可以在物理上等效于某些非引力场理论。这类似于全息图的工作原理：你可以只从二维全息图重建整个三维图像。弦论全息，也被称为AdS/CFT对应，已经被应用于弦和粒子理论家感兴趣的各种理论问题，并且在夸克-胶子等离子体和凝聚态现象的建模方面也取得了部分进展。它引发了新类型的引力时空的发现，并加强了信息论纠缠和时空几何之间的概念联系。促进发展全息术是本提案的另一个主题。

My long term goal is to understand how to reconcile Einstein's theory of gravity with quantum mechanics, with a special interest in the physics of black holes. To investigate this, I use string theory, which is currently the best-developed theoretical framework available for doing computations of interest in quantum gravitational physics. String theory is an appropriate toolset because it manages to encompass both the smooth spacetime geometry of gravity on large scales and the probabilistic uncertainty of quantum mechanics on small scales. Two related advances in string theory technology in the past nineteen years have helped make my long term goal more accessible.    The first advance was the discovery of higher-dimensional objects known as D-branes in string theory, which co-exist alongside the one-dimensional fundamental strings. D-branes are versatile theoretical beasts, because they gravitate and carry charges. Applications were quickly discovered which shed new light on longstanding fundamental questions about the physics of black holes. E.g. string technologies applied to a variety of special higher-dimensional black holes enabled the first quantitative derivation from first principles of the Bekenstein-Hawking entropy, a quantity akin to disorganization which encodes the large number of ways a black hole could be formed in gravitational collapse. String theory models with many moving parts also have the potential to address another more complicated question: Hawking's famous black hole information paradox, which concerns the fate of information that falls into black holes. Much progress has been made, but still more territory remains to be understood. Contributing to developing microscopic string theory models of black hole physics further is one of the twin themes of this research proposal.    The second advance was a surprising and powerful new discovery that certain gravitational theories with negative cosmological constant possessing one extra dimension of space can be physically equivalent to certain non-gravitational field theories. This is akin to how holograms work: you can reconstruct the whole three-dimensional image from only the two-dimensional hologram. String theory holography, also known as the AdS/CFT correspondence, has been applied to a wide variety of theoretical problems of interest for string and particle theorists, and has also produced partial progress on modelling aspects of the quark-gluon plasma and condensed matter phenomena. It has sparked discovery of new types of gravitational spacetimes, and strengthened the conceptual connections between information theoretic entanglement and the geometry of spacetime. Contributing to developing holography is the other main theme of this proposal.