Post-Newtonian cosmological modelling
Post-Newtonian cosmological modelling
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后牛顿宇宙学模型
DOI：
10.1103/physrevd.91.103532
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发表时间：
2015
影响因子：
5
通讯作者：
T. Clifton
中科院分区：
文献类型：
--
作者：
V. Sanghai;T. Clifton
我们开发了一种构建宇宙学模型的新方法，其中受扰动的闵可夫斯基空间的小块在反射对称边界处连接在一起，以形成全局的动态时空。这个拼凑而成的宇宙的每一部分都是用后牛顿引力物理学来描述的，宇宙的大规模膨胀是一种新兴现象。这种宇宙学方法不需要对非局部平均过程做出任何假设。我们的框架阐明了广义相对论的弱场极限与通过一组对称假设求解爱因斯坦方程所得到的宇宙学解之间的关系。它还允许以明确的方式研究结构形成对宇宙大规模膨胀的影响。作为一个明确的例子，我们使用这种形式主义来研究大量规则排列的点状质量的宇宙学行为。在这种情况下，我们发现大规模膨胀可以通过类弗里德曼方程很好地建模，该方程包含采用尘埃、辐射和空间曲率形式的项。辐射项虽然比尘埃项小，但纯粹是爱因斯坦方程非线性的结果。
We develop a new approach to building cosmological models, in which small pieces of perturbed Minkowski space are joined together at reflection-symmetric boundaries in order to form a global, dynamical space-time. Each piece of this patchwork universe is described using post-Newtonian gravitational physics, with the large-scale expansion of the universe being an emergent phenomenon. This approach to cosmology does not require any assumptions about non-local averaging processes. Our framework clarifies the relation between the weak-field limit of general relativity, and the cosmological solutions that result from solving Einstein's equations with a set of symmetry assumptions. It also allows the effects of structure formation on the large-scale expansion of the universe to be investigated in an unambiguous way. As an explicit example, we use this formalism to investigate the cosmological behaviour of a large number of regularly arranged point-like masses. In this case we find that the large-scale expansion is well modelled by a Friedmann-like equation that contains terms that take the form of dust, radiation, and spatial curvature. The radiation term, while small compared to the dust term, is purely a result of the non-linearity of Einstein's equations.