Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information
Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information
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DOI：
10.1007/jhep08(2020)044
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发表时间：
2020-02
影响因子：
5.4
通讯作者：
D. Marolf;Henry Maxfield
中科院分区：
文献类型：
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作者：
D. Marolf;Henry Maxfield
在20世纪80年代，科尔曼、吉丁斯和斯特罗明格的工作将时空虫洞的物理学与“婴儿宇宙”和一系列理论联系起来。我们重新审视了这些想法，使用与负宇宙常数和渐近AdS边界相关的特征来加强结果，引入视角的变化，并与最近关于Page曲线的复制虫洞讨论联系起来。一个关键的新特性是强调了空状态的作用。我们在体积的简单拓扑模型中详细探讨了这种结构，使我们能够计算相关边界理论的全谱。渐近AdS希尔伯特空间的维数变成了一个随机变量Z，其值可以小于理论中独立状态的朴素数k。对于k> Z，一致性来自于由引力路径积分定义的内积的精确简并，因此许多先验的独立状态只与零态不同。我们认为类似的性质在任何一致的引力路径积分中都必须成立。我们还评论了对更复杂模型的外推的其他方面，以及对上述综合体中单个成员的黑洞信息问题的可能含义。
In the 1980’s, work by Coleman and by Giddings and Strominger linked the physics of spacetime wormholes to ‘baby universes’ and an ensemble of theories. We revisit such ideas, using features associated with a negative cosmological constant and asymptotically AdS boundaries to strengthen the results, introduce a change in perspective, and connect with recent replica wormhole discussions of the Page curve. A key new feature is an emphasis on the role of null states. We explore this structure in detail in simple topological models of the bulk that allow us to compute the full spectrum of associated boundary theories. The dimension of the asymptotically AdS Hilbert space turns out to become a random variable Z, whose value can be less than the naive number k of independent states in the theory. For k> Z, consistency arises from an exact degeneracy in the inner product defined by the gravitational path integral, so that many a priori independent states differ only by a null state. We argue that a similar property must hold in any consistent gravitational path integral. We also comment on other aspects of extrapolations to more complicated models, and on possible implications for the black hole information problem in the individual members of the above ensemble.