Research on Quantum Gravity and Quantum Foundations

这个项目是针对量子引力，这是物理学家如何提到的问题，统一这两个 物理理论在其目前发展状态的主要支柱：量子理论和广义相对论。 一 这个问题的解决方案通常被期望告诉我们最小的时空结构 长度尺度，也有助于回答为什么宇宙在最大尺度上是这样的问题。 我对这个问题的研究方法是基于因果集理论，该理论假设， 时空是一个因果集，一种广义的家谱，技术上称为“偏序”。 在此基础上建立量子引力理论是困难的，因为基本概念是 不熟悉 代替运动方程，我们有一个生长过程，描述了因果关系的不断诞生。 集合元素--“时空的原子”。 尽管如此， 在过去的几年里，第一个是因果集上的量子场论的公式，第二个是量子场论的公式。 发现了爱因斯坦-希尔伯特作用量的类似物--因果集本身的泛函。 该项目将跟踪这两项进展。 在此基础上，我们将研究 黑洞对霍金辐射的影响 基于后者，我们将执行计算机 模拟，以了解因果集是否能够产生一个近似的时空，不仅在 在原则上，也在实践中。 这项研究计划的一个相关部分涉及量子基金会，我认为这是一项奋进， 与量子引力交织在一起，以至于一的进步最终将取决于一的进步。 另一 这里的定义问题是，量子形式主义对什么样的微观现实 推荐？ 计划中的研究将进一步发展我们中的一些人已经提出的这个问题的答案 提出，根据量子现实是“建立在经典现实”在很大程度上相同的方式 像x（y+z）+w这样的多项式是由不定数x，y，z和w构成的。

This project is directed to quantum gravity, which is how physicists refer to the problem of unifying the two main pillars of physical theory in its current state of development: Quantum Theory and General Relativity. A solution of this problem is generally expected to tell us about the structure of spacetime on the smallest length scales, and also to help answer questions about why the cosmos is as it is on the largest scales. My approach to this problem is based on causal set theory, which hypothesizes that the deep structure of spacetime is that of a causal set, a kind of generalized family tree, known technically as a "partial order". To formulate a theory of quantum gravity on this basis is difficult, because the basic concepts are so unfamiliar. Instead of equations of motion, one has a growth process describing the continual birth of causal set elements --- the "atoms of spacetime". Nevertheless, two major strides forward have been taken in the last couple of years, the first being a formulation of a quantum field theory on a causal set, the second being the discovery of an analog of the Einstein-Hilbert action- functional for the causal set itself. The project will follow up on these two pieces of progress. Based on the former, we will study the effect of spacetime atomicity on Hawking radiation by a black hole. Based on the latter, we will perform computer simulations to learn whether the causal set is able to give rise to an approximate spacetime, not only in principle but also in practice. A related strand of this research-proposal concerns Quantum Foundations, an endeavor which I believe to be intertwined with Quantum Gravity to the extent that progress in the one will ultimately depend on progress in the other. The defining question here is, To what sort of microscopic reality does the quantum formalism refer? The projected research would develop further a proposed answer to this question which some of us have put forward, according to which a quantum reality is "built out of classical realities" in much the same way that a polynomial like x(y+z)+w is built out of the indeterminates x, y, z, and w.