The big bang and the Schwarzschild singularities are space-like. They are generally regarded as the ‘final frontiers’ at which space–time ends and general relativity breaks down. We review the status of such space-like singularities from three increasingly more general perspectives. They are provided by (i) A reformulation of classical general relativity motivated by the Belinskii, Khalatnikov, Lifshitz conjecture on the behavior of the gravitational field near space-like singularities; (ii) The use of test quantum fields to probe the nature of these singularities; and, (iii) An analysis of the fate of these singularities in loop quantum gravity due to quantum geometry effects. At all three levels singularities turn out to be less menacing than one might a priori expect from classical general relativity. Our goal is to present an overview of the emerging conceptual picture and suggest lines for further work. In line with the Introduction to Current Research theme, we have made an attempt to make it easily accessible to all researchers in gravitational physics.

大爆炸和史瓦西奇点是类似太空的。它们通常被认为是时空终结和广义相对论崩溃的“最终边界”。我们从三个越来越普遍的角度回顾了这种类空间奇点的状态。它们是由 (i) Belinskii、Khalatnikov、Lifshitz 猜想推动的关于类空间奇点附近引力场行为的经典广义相对论的重新表述；(ii) 使用测试量子场来探测这些奇点的性质；(iii) 分析由于量子几何效应导致的环量子引力中这些奇点的命运。在所有三个层面上，奇点的威胁性都低于经典广义相对论的先验预期。我们的目标是概述新兴的概念图并为进一步的工作提出建议。符合介绍当前研究主题，我们试图让引力物理学的所有研究人员都能轻松访问它。