Question of measuring spatial curvature in an inhomogeneous universe
Question of measuring spatial curvature in an inhomogeneous universe
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DOI：
10.1103/physrevd.103.083513
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
C. Tian;S. Anselmi;M. Carney;J. Giblin;J. Mertens;G. Starkman
中科院分区：
文献类型：
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作者：
C. Tian;S. Anselmi;M. Carney;J. Giblin;J. Mertens;G. Starkman
时空的曲率，无论是在拓扑意义上，还是在超视界大小的斑块上的平均值，通常都等同于弗里德曼方程中出现的整体曲率项。然而，一般来说，宇宙是不均匀的，引力是一个非线性理论，因此任何曲率扰动都违反了FLRW模型的假设;在恒定时间表面上平均的局部曲率不一定会再现全局对称性的观测效果。此外，常时超曲面的曲率不是一个可观测的量，只能间接推断。在这里，我们研究曲率模式的行为在一个精确的完全相对论性的设置扰动时空的超曲面，以及这个曲率如何对应于观察者推断。我们还注意到，在这一点上的意见变得敏感的曲率来源的不均匀性推断的平均性能的影响，发现一般协议与过去的文献。
The curvature of a spacetime, either in a topological sense, or averaged over super-horizon-sized patches, is often equated with the global curvature term that appears in Friedmann's equation. In general, however, the Universe is inhomogeneous, and gravity is a nonlinear theory, thus any curvature perturbations violate the assumptions of the FLRW model; it is not necessarily true that local curvature, averaged over patches of constant-time surfaces, will reproduce the observational effects of global symmetry. Further, the curvature of a constant-time hypersurface is not an observable quantity, and can only be inferred indirectly. Here, we examine the behavior of curvature modes on hypersurfaces of a perturbed spacetime in an exact fully relativistic setting, and how this curvature corresponds with that inferred by observers. We also note the point at which observations become sensitive to the impact of curvature sourced by inhomogeneities on inferred average properties, finding general agreement with past literature.