In this review, we provide a concrete overview of the Raychaudhuri equation, Focusing Theorem and convergence conditions in a plethora of backgrounds and discuss the consequences. We also present various classical and quantum approaches suggested in the literature that could potentially mitigate the initial big-bang singularity and the black-hole singularity.

中文翻译：

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重新审视 Raychaudhuri 方程的经典和量子方面以及奇点的可能解决方案

在这篇综述中，我们具体概述了 Raychaudhuri 方程、聚焦定理和多种背景下的收敛条件，并讨论了其后果。我们还提出了文献中提出的各种经典和量子方法，这些方法可能会减轻初始大爆炸奇点和黑洞奇点。