Classification of Extremal Black Holes

广义相对论是我们研究引力的理论。它导致了我们宇宙在大尺度上的一个非常精确的模型。它最大胆的预测是黑洞的存在，黑洞是一种巨大的物体，形成了一个没有任何东西可以逃脱的空间区域。现在人们已经接受黑洞确实存在于我们的宇宙中--这是一个抽象理论如何具有深刻物理意义的突出例子。 尽管它取得了成功，但GR一直拒绝尝试使其与量子力学保持一致，量子力学同样擅长描述自然的基本组成部分。这样一个“量子引力”理论需要回答一些大问题，比如我们的宇宙是如何形成的。幸运的是，黑洞提供了一个独特的实验室来研究这个难题-它们的引力场是如此强烈，以至于量子力学和GR的影响都发挥了作用。我的研究重点是更高维度的黑洞。我们都熟悉四维--一个事件有四个标签，三个是“在哪里”，一个是“何时"发生。但是弦理论，量子引力理论的主要候选者，需要的不仅仅是四维。在大尺度上，它减少到GR，促使我们研究大于4维的黑洞。关于四维平衡态黑洞，我们已经知道得很多。它们的形状就像一个球的表面，它们被独特地“标记”为它们的质量和自旋。这些非凡的特性在更高的维度中不再成立。最近发现的黑环--甜甜圈形状的黑洞--不仅证明了许多形状都是可能的，而且证明了独特性已经丧失。 我工作的中心目标是在更高的维度上对黑洞进行分类，检查黑洞非唯一性的程度，并确定如何在量子引力中解决这个问题。为了实现这些具有挑战性的目标，我的策略是瞄准一种特殊类型的黑洞，我已经证明这种黑洞最容易分析。我的研究将大大有助于更深入地了解量子引力，并培养学生在其他领域有价值的独特的定量技能。像大多数基础研究一样，它不太可能立即造福社会。但它可以帮助我们从根本上理解自然，我相信这是一个值得追求的目标。

General relativity (GR) is our theory to study gravitation. It has led to a very accurate model of our Universe at large scales. Its boldest prediction is the existence of black holes, massive objects that form a region of space from which nothing can escape. It is now accepted that black holes really exist in our Universe - a striking example of how abstract theory can have profound physical significance. Despite its successes, GR has resisted attempts to make it consistent with quantum mechanics, which is equally adept at describing the basic constituents of Nature. Such a theory of `quantum gravity' is needed to answer big questions, like how our Universe formed. Luckily, black holes offer a unique laboratory to study this difficult problem - their gravitational fields are so intense that effects from both quantum mechanics and GR come into play. My research focusses on black holes in higher dimensions. We are all familiar with four dimensions - an event has four labels, three for 'where' and one for `when' it occurred. But string theory, a leading candidate for a theory of quantum gravity, requires more than four dimensions. At large scales, it reduces to GR, impelling us to investigate black holes in dimensions greater than four. Much is known about equilibrium black holes in four dimensions. They are shaped like the surface of a ball, and they are uniquely `labelled' by their mass and spin. These remarkable properties no longer hold in higher dimensions. The recent discovery of black rings - donut shaped black holes - proves not only that many shapes are possible, but that uniqueness is lost. The central goals of my work are to classify black holes in higher dimensions, examine the extent of black hole non-uniqueness, and determine how this issue is resolved within quantum gravity. To achieve these challenging objectives, my strategy is to target a special type of black hole which I have shown are simplest to analyse. My research will contribute significantly to a deeper understanding of quantum gravity, and train students with unique quantitative skills valued in other fields. Like most basic research, it is unlikely to immediately benefit society. But it could help us understand Nature at a fundamental level, which I believe is a worthwhile aim.