Black holes and cosmology in quantum gravity

“量子引力”一词用于描述任何将量子力学的思想应用于引力的理论的尝试。这个研究领域起源于一个被广泛接受的观点，即小尺度物体（如基本粒子）的物理学是由量子理论描述的，重力也应该是如此。大尺度上的万有引力，比如太阳系和更远的地方，已经被很好地理解了；牛顿的理论很好地近似于我们所看到的，但已经被爱因斯坦的广义相对论所取代。这一理论预测了新的效应，如重力导致的光的弯曲，并得到了实验的证实。然而，爱因斯坦的理论在极端情况下是失败的，比如一颗大质量恒星的引力坍缩，或者我们宇宙的剧烈起源。在这两种情况下，在非常小的距离上未知的物理性质变得很重要。目前，只有部分量子的不完全混合理论是可行的。它预测黑洞会发射辐射，并最终变得比基本粒子还小。在某种程度上，它还以一种似乎与早期量子引力时代脱节的方式描述了我们现在的宇宙状态。我的研究项目的目标是发展一些想法，使我们能够更深入地理解引力的量子本质，因为它适用于非常早期的宇宙，以及黑洞演化的非常晚期。我提出的框架是一个可以用计算机模拟描述物质和几何构型的量子态演化的框架。

The term "Quantum gravity" is used to describe any attempt at a theory that applies ideas from quantum mechanics to gravitation. This research area has its origins in the widely accepted view that the physics of small scale objects, such as elementary particles, is described by quantum theory, and that the same should be true for gravity.   Gravitation on large scales, such as the solar system and beyond, is well understood; Newton's theory is a very good approximation to what we see, but has been superseded by Einstein's general relativity. This theory has predicted new effects, such as the bending of light by gravity, that are experimentally verified.  However, Einstein's theory fails  in extreme situations, such as the gravitational collapse of a massive star, or the violent beginning of our universe. In both instances the unknown properties of physics at very small distances become important. At present an incomplete hybrid theory that is only part quantum is available. It predicts that black holes emit radiation, and eventually become smaller than the size of elementary particles. To an extent it also describes the state of our present universe in a way that appears disconnected from its very early quantum gravity era. The goal of my research program is to develop ideas that will allow a deeper understanding of the quantum nature of gravity as it applies to the very early universe, and the very late stages of black hole evolution. The framework I propose is one in which it is possible to simulate using a computer the evolution of quantum states describing configurations of matter and geometry.