Creation and Evolution of Nonlinear Inhomogeneous Spacetime Structures and Numerical Cosmology

非线性非齐次时空结构的产生和演化与数值宇宙学

• 批准号: 02640238
• 负责人: MAEDA Kei-ichi
• 金额: $ 1.54万
• 依托单位: Waseda University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640238/
• 关键词: General Relativity; Cosmology; Numerical Relativity; Inhomogeneous Universe; Black Holes; Quantum Cosmology; Phase Transition; Large Scale Structure

In this research, we discussed the problems on inhomogeneity of the Universe, in particular, on creation and evolution of inhomogeneous spacetime.1. The one of main topics in this research is whether the inhomogeneous universes evolve into the present universe through inflation. In order to investigate this subject, we first presented a formalism of numerical cosmology, which is a natural extension of numerical relativity for gravitational collapse.(1) We found the following two results :(i) Goldwirth and Piran calculated 1 dimensional spherically symmetric case, while we discussed 1 dimensional planar symmetric spacetime with cosmological constant in order to discuss inhomogeneity due to gravitational waves. We found that all spacetime evolve into de Sitter space. This strongly supports the cosmic no-hair conjecture.(ii) From our simulation and by an analysis of exact solutions, we proposed "Cosmic Hoop Conjecture" by which we can discuss on an inflationary scenario for general inhomo … More geneous spacetime.(2) For the homogeneous but anisotropic universe, we generalized Wald's theorem for the case of power-law inflation, which may be realized in generalized einstein theories discussed below.2. We also considered cosmology in generalized Einstein theories (GETs) such as Brans-Dicke theory. :(1) Although new and chaotic inflation need a fine-tuning in coupling constants, if we consider those in GETs, then such constraints is loosened. We call this model soft inflation.(2) In extended inflation, nucleated bubbles produce inhomogeneity of the Universe. The original model seems to be excluded from observation by a rough analysis of bubble expansion. However, we found by a detailed analysis that bubbles are nucleated in the Hawking-Moss mode instead of the Coleman-De Lucia mode, and the thin wall approximation is broken in an initial stage of inflation. This may change a scenario of the extended inflation model.(3) The structure formation in the Universe is one of the most important topics in cosmology, but no one knows yet what is a real mechanism. Using GETs, we looked for a new mechanism. In particular, we considered the theory with non-minimal coupling, which predicts an oscillation in Hubble parameter and then provides us a slow expanding phase of the Universe. We, hence, expect a rapid growth of the density perturbations in the slow expansion phase. For some parameters, we really found a large enhancement of the density perturbations. Unfortunately, the Universe must had an unphysical era in the past, when the effective gravitational constant was negative. Less

在这项研究中，我们讨论了有关宇宙不均匀性的问题，尤其是关于不均匀时空的创造和进化的问题。1。这项研究的主要主题之一是，不均匀的宇宙是否通过通货膨胀演变为当前宇宙。 In order to investigate this subject, we first presented a formatism of numerical cosmology, which is a natural extension of numerical relativity for gravitational collapse.(1) We found the following two results :(i) Goldwirth and Piran calculated 1 dimensional symmetric case, while we discussed 1 dimensional planar symmetric spacetime with cosmological constant in order to discuss inhomogeneity due to gravitational waves.我们发现所有时空都会演变成De Sitter空间。这强烈支持宇宙的无头发的猜想。（ii）通过我们的模拟和确切解决方案的分析，我们提出了“宇宙箍猜想”，我们可以通过该概述在通货膨胀的情况下讨论一般的inhomo…更加宽敞的时空的通货膨胀场景。爱因斯坦理论下面讨论了2。我们还考虑了宇宙化的爱因斯坦理论（GET），例如Br​​ans-Dicke理论。 ：（1）尽管新的和混乱的通货膨胀需要在耦合常数中进行微调，但如果我们考虑到其中的那些，那么这种约束就会松动。我们称这种模型软通胀。（2）在扩展通货膨胀中，核气泡会产生宇宙的不均匀性。通过对气泡扩展的粗略分析，原始模型似乎被排除在观察之外。但是，我们通过详细的分析发现，气泡在鹰派模式下而不是Coleman-de Lucia模式进行了核化，并且在通货膨胀的初始阶段，薄壁近似被损坏。这可能会改变扩展通货膨胀模型的场景。（3）宇宙中的结构形成是宇宙学中最重要的主题之一，但是没人知道什么是真正的机制。使用Get，我们寻找了一种新机制。特别是，我们考虑了具有非最小耦合的理论，该理论预测了哈勃参数的振荡，然后为我们提供了宇宙的缓慢扩展阶段。因此，我们期望在缓慢的膨胀阶段的密度扰动迅速增长。对于某些参数，我们确实发现了密度扰动的大量增强。不幸的是，过去的有效重力常数为负时，宇宙过去必须具有一个非物理的时代。较少的

项目成果

D.H.Corcle: "Wormholes with Scalar Fields" Classical and Quantum Gravity. 7. 955-963 (1990)

D.H.Corcle：“带有标量场的虫洞”经典和量子引力。

J.D.Barrow: "Extended Inflationary Universes" Nuclear Physics. B341. 294-308 (1990)

J.D.Barrow：“扩展的暴胀宇宙”核物理。

A.L.Berkin: "Inflation in Gencraliged Einstein Theorios" Physial Review D. 44. 1691-1704 (1991)

A.L.Berkin：“广义爱因斯坦理论中的通货膨胀”物理评论 D. 44. 1691-1704 (1991)

A.L.Berkin: "The Effects of R^3 and R□R Terms on R^2 Inflation" Physics Letters. 245B. 348-354 (1990)

A.L.Berkin：“R^3 和 R□R 项对 R^2 通货膨胀的影响”《物理快报》245B（1990 年）。

中尾 憲一: "Initial Data of Axisymmetric Gravifational Waves with a Cosmological Constant" 「Approaches to Numerical Relativity」. (1992)

Kenichi Nakao：“具有宇宙学常数的轴对称引力波的初始数据”“数值相对论的方法”（1992）。