We portray the structure of quantum gravity emerging from recent progress in understanding the quantum mechanics of an evaporating black hole. Quantum gravity admits two different descriptions, based on Euclidean gravitational path integral and a unitarily evolving holographic quantum system, which appear to present vastly different pictures under the existence of a black hole. Nevertheless, these two descriptions are physically equivalent. Various issues of black hole physics — including the existence of the interior, unitarity of the evolution, the puzzle of too large interior volume, and the ensemble nature seen in certain calculations — are addressed very differently in the two descriptions, still leading to the same physical conclusions. The perspective of quantum gravity developed here is expected to have broader implications beyond black hole physics, especially for the cosmology of the eternally inflating multiverse.

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从黑洞之谜到量子引力的结构

我们描绘了最近在理解蒸发黑洞的量子力学方面取得的进展而出现的量子引力结构。量子引力有两种不同的描述，基于欧几里得引力路径积分和单一演化的全息量子系统，它们似乎在黑洞存在下呈现出截然不同的画面。然而，这两种描述在物理上是等价的。黑洞物理学的各种问题——包括内部的存在、演化的统一性、内部体积过大的谜团以及某些计算中看到的整体性质——在两种描述中的处理方式截然不同，但仍然导致相同的结果物理结论。