Pseudo rip的性质

发布时间：2018-03-04 01:28

本文选题：暗能量　切入点：pseudo　出处：《广西师范大学》2012年硕士论文　论文类型：学位论文

【摘要】：本文首先介绍宇宙学的基础知识,宇宙是世界最大的物质,人类诞生不久便开始探索宇宙。宇宙学是从整体的角度来研究宇宙的起源、演化和结构以及超星系团以上结构的学科。在众多宇宙模型中由弗里德曼、罗伯特和沃克等人建立的标准宇宙模型是最重要的宇宙模型。在这种模型中宇宙产生于一次大爆炸,经过一系列复杂的演化,形成了现在的样子。近年来随着科学技术的发展,越来越多的观测数据表明宇宙在加速膨胀。大多数物理学家相信宇宙加速膨胀是由一种奇异的能量引起的,人们称它为暗能量。人们为暗能量设计了多种模型,其中宇宙学常数模型、Quintessence模型、Phantom模型以及Quintom模型是比较有名的暗能量模型,另外修改引力理论也是解释宇宙加速膨胀的重要理论。宇宙加速膨胀的发现使人们对宇宙的结局提出更多的设想,在Phantom暗能量场中,暗能量的密度将在某一时刻达到无穷大,宇宙将在未来发生大破裂,人们称为big rip,后来,有人提出了宇宙的另外一种结局little rip。不久以前,Frampton等人提出了pseudo rip这个概念,它表示暗能量密度最终趋向一个常数的宇宙结局。对于big rip和little rip已经有了许多研究,因此本文研究pseudo rip这个新提出的概念。本文在第三章研究pseudo rip基本性质,分析宇宙在pseudo rip的情况下,宇宙的能量密度、压强、状态方程以及惯性力等宇宙学基本参数的情况,并由此认为如果宇宙的结局是Pseudo rip的话,宇宙学常数很有可能就是暗能量。我们在研究宇宙学时一般假设宇宙是一种理想流体,理想流体是一种无黏性的流体,本文的第四章将分析理想流体情况下的pseudo rip在黏性流体中的变化情况。黏性流体能产生剪切、膨胀、扭转等作用,其中膨胀会改变宇宙的压强,最终使宇宙的结局可能变成little rip。本文的第五章研究在pseudo rip情况下,单标量场和双标量场的性质。如果宇宙的结局是Pseudo rip的话,本文认为标量场中拉氏量的动能项的值将很小,并且会逐渐趋向于0,只剩下势能项。扰动理论是宇宙学中的重要理论,本章把重点部分放在分析标量场在扰动下的稳定性对于哈勃常数形式的要求。由于pseudo rip不像其它其它的宇宙结局,哈勃常数将趋向无穷大,可以说它的各个参数相对比较稳定,因此我们完全可以选择适当的动能项系数使标量场在扰动下的稳定性和哈勃参数中系数无关,也可以选择适当的动能项系数,使标量场在扰动下的稳定性和哈勃常数的具体形式无关。
[Abstract]:This paper first introduces the basic knowledge of cosmology. The universe is the largest material in the world, and mankind began to explore the universe shortly after its birth. Cosmology studies the origin of the universe from a holistic perspective. The discipline of evolution and structure, and the structure above the supercluster. The standard cosmic model established by Friedman, Robert, Walker, and others, among many cosmic models, is the most important cosmic model in which the universe is born out of a big bang. After a series of complex evolutions, it became what it is. In recent years, with the development of science and technology, more and more observational data show that the universe is expanding rapidly. Most physicists believe that the accelerating expansion of the universe is caused by a strange energy. People call it dark energy. There are many models for dark energy, including the cosmological constant model, the Quintessence model, the Phantom model and the Quintom model, which are known as dark energy models. In addition, the modification of gravity theory is also an important theory to explain the accelerating expansion of the universe. The discovery of the accelerating expansion of the universe has led to more assumptions about the outcome of the universe. In the Phantom dark energy field, the density of dark energy will reach infinity at some point, and the universe will break apart in the future, known as big, later, Some people have put forward another kind of ending of the universe, little RRP. Not long ago, the concept of pseudo rip was put forward by big Frampton et al. It indicates that the dark energy density eventually tends to a constant cosmic ending. There has been a lot of research on big rip and little rip. In the third chapter, we study the basic properties of pseudo rip and analyze the basic cosmological parameters such as energy density, pressure, equation of state, inertial force and so on in the case of pseudo rip. It is concluded that if the end of the universe is Pseudo rip, the cosmological constant is probably dark energy. When we study cosmology, we generally assume that the universe is an ideal fluid, that an ideal fluid is a non-viscous fluid. The 4th chapter of this paper will analyze the change of pseudo rip in viscous fluid under ideal fluid condition. Viscous fluid can produce shear, expansion, torsion and so on, in which expansion will change the pressure of the universe and eventually make the outcome of the universe become little Rip. In chapter 5th, we study the properties of single scalar field and double scalar field in the case of pseudo rip. If the result of the universe is Pseudo rip, we think that the kinetic energy term of the Lagrangian in the scalar field will be very small. And will tend to zero, leaving only the potential energy term. Perturbation theory is an important theory in cosmology. This chapter focuses on the analysis of the requirements of the stability of the scalar field under perturbation for the Hubble constant form. Since pseudo rip will tend to infinity unlike other cosmological outcomes, it can be said that the various parameters of the scalar field are relatively stable. Therefore, we can choose the appropriate kinetic energy term coefficient to make the stability of scalar field under disturbance independent of the coefficient in the Hubble parameter, or we can choose the appropriate kinetic energy term coefficient. The stability of the scalar field under perturbation is independent of the specific form of the Hubble constant.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：P159

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