封闭类时曲线、奇点与因果性：从哥德尔到时序保护的考察
Closed Timelike Curves, Singularities and Causality: A Survey from Gödel to Chronological Protection
摘要：
我给出了一个历史的调查讨论封闭的类时曲线的存在，在广义相对论模型的宇宙，开放的物理可能性的时间旅行在过去，首先认识到K。哥德尔在1949年提出的旋转宇宙模型。我要强调的是，回到过去的旅行与缺乏类时奇点的时空模型密切相关。由于这种奇点是广义相对论方程在物理上合理的假设下的必然结果，因此只有当这些假设中的一个或另一个被违反时，过去的时间旅行才成为可能。这是虫洞型解决方案的情况。S.霍金和其他作者曾试图通过提倡时间顺序保护的物理机制来“拯救”过去时间旅行的矛盾后果;然而，即使考虑到视界附近的量子涨落，这种机制目前仍然未知。我以因果动力三角剖分（Causal Dynamical Triangulations）的简短而乏味的讨论来结束这篇综述，这是一种研究量子引力的方法，因果关系在其中扮演着重要的角色。
英文摘要：
I give a historical survey of the discussions about the existence of closed timelike curves in general relativistic models of the universe, opening the physical possibility of time travel in the past, as first recognized by K. Gödel in his rotating universe model of 1949. I emphasize that journeying into the past is intimately linked to spacetime models devoid of timelike singularities. Since such singularities arise as an inevitable consequence of the equations of general relativity given physically reasonable assumptions, time travel in the past becomes possible only when one or another of these assumptions is violated. It is the case with wormhole-type solutions. S. Hawking and other authors have tried to "save" the paradoxical consequences of time travel in the past by advocating physical mechanisms of chronological protection; however, such mechanisms remain presently unknown, even when quantum fluctuations near horizons are taken into account. I close the survey by a brief and pedestrian discussion of Causal Dynamical Triangulations, an approach to quantum gravity in which causality plays a seminal role.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
