Cosmology without averaging
Cosmology without averaging
复制标题
没有平均的宇宙学
DOI：
10.1088/0264-9381/28/16/164011
复制
发表时间：
2010
影响因子：
3.5
通讯作者：
T. Clifton
中科院分区：
文献类型：
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作者：
T. Clifton
我们构建了由大量相同的、规则间隔的质量组成的宇宙学模型。这些模型不依赖于任何平均程序，或对存在的全球弗里德曼-罗伯逊-步行者（FRW）的背景。它们是爱因斯坦方程的解，直到微扰膨胀中的高阶修正，并且具有由弗里德曼方程很好地模拟的大尺度动力学。我们发现，任意大的密度对比的存在并不改变大尺度膨胀的幅度或规模，至少当群众是有规律地安排，并达到规定的精度水平。我们还发现，虽然每个细胞内的局部时空几何可以被描述为线性扰动FRW，人们可以说，一个更自然的描述是扰动闵可夫斯基空间（在这种情况下，标量扰动是简单的牛顿势）。我们希望这些模型可以用于理解和测试宇宙学中的平均思想，以及澄清全球宇宙动力学和与孤立质量相关的静态时空之间的关系。
We construct cosmological models consisting of large numbers of identical, regularly spaced masses. These models do not rely on any averaging procedures, or on the existence of a global Friedmann–Robertson–Walker (FRW) background. They are solutions of Einstein's equations, up to higher order corrections in a perturbative expansion, and have large-scale dynamics that are well modelled by the Friedmann equation. We find that the existence of arbitrarily large density contrasts does not change either the magnitude or scale of the large-scale expansion, at least when masses are regularly arranged, and up to the prescribed level of accuracy. We also find that while the local spacetime geometry inside each cell can be described as linearly perturbed FRW, one could argue that a more natural description is that of perturbed Minkowski space (in which case the scalar perturbations are simply Newtonian potentials). We expect these models to be of use for understanding and testing ideas about averaging in cosmology, as well as clarifying the relationship between global cosmological dynamics and the static spacetimes associated with isolated masses.