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  本文選題：暗能量　切入點：pseudo　出處：《廣西師范大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：本文首先介紹宇宙學(xué)的基礎(chǔ)知識,宇宙是世界最大的物質(zhì),人類誕生不久便開始探索宇宙。宇宙學(xué)是從整體的角度來研究宇宙的起源、演化和結(jié)構(gòu)以及超星系團以上結(jié)構(gòu)的學(xué)科。在眾多宇宙模型中由弗里德曼、羅伯特和沃克等人建立的標(biāo)準(zhǔn)宇宙模型是最重要的宇宙模型。在這種模型中宇宙產(chǎn)生于一次大爆炸,經(jīng)過一系列復(fù)雜的演化,形成了現(xiàn)在的樣子。 近年來隨著科學(xué)技術(shù)的發(fā)展,越來越多的觀測數(shù)據(jù)表明宇宙在加速膨脹。大多數(shù)物理學(xué)家相信宇宙加速膨脹是由一種奇異的能量引起的,人們稱它為暗能量。人們?yōu)榘的芰吭O(shè)計了多種模型,其中宇宙學(xué)常數(shù)模型、Quintessence模型、Phantom模型以及Quintom模型是比較有名的暗能量模型,另外修改引力理論也是解釋宇宙加速膨脹的重要理論。 宇宙加速膨脹的發(fā)現(xiàn)使人們對宇宙的結(jié)局提出更多的設(shè)想,在Phantom暗能量場中,暗能量的密度將在某一時刻達到無窮大,宇宙將在未來發(fā)生大破裂,人們稱為big rip,后來,有人提出了宇宙的另外一種結(jié)局little rip。不久以前,Frampton等人提出了pseudo rip這個概念,它表示暗能量密度最終趨向一個常數(shù)的宇宙結(jié)局。對于big rip和little rip已經(jīng)有了許多研究,因此本文研究pseudo rip這個新提出的概念。本文在第三章研究pseudo rip基本性質(zhì),分析宇宙在pseudo rip的情況下,宇宙的能量密度、壓強、狀態(tài)方程以及慣性力等宇宙學(xué)基本參數(shù)的情況,并由此認為如果宇宙的結(jié)局是Pseudo rip的話,宇宙學(xué)常數(shù)很有可能就是暗能量。 我們在研究宇宙學(xué)時一般假設(shè)宇宙是一種理想流體,理想流體是一種無黏性的流體,本文的第四章將分析理想流體情況下的pseudo rip在黏性流體中的變化情況。黏性流體能產(chǎn)生剪切、膨脹、扭轉(zhuǎn)等作用,其中膨脹會改變宇宙的壓強,最終使宇宙的結(jié)局可能變成little rip。 本文的第五章研究在pseudo rip情況下,單標(biāo)量場和雙標(biāo)量場的性質(zhì)。如果宇宙的結(jié)局是Pseudo rip的話,本文認為標(biāo)量場中拉氏量的動能項的值將很小,并且會逐漸趨向于0,只剩下勢能項。擾動理論是宇宙學(xué)中的重要理論,本章把重點部分放在分析標(biāo)量場在擾動下的穩(wěn)定性對于哈勃常數(shù)形式的要求。由于pseudo rip不像其它其它的宇宙結(jié)局,哈勃常數(shù)將趨向無窮大,可以說它的各個參數(shù)相對比較穩(wěn)定,因此我們完全可以選擇適當(dāng)?shù)膭幽茼椣禂?shù)使標(biāo)量場在擾動下的穩(wěn)定性和哈勃參數(shù)中系數(shù)無關(guān),也可以選擇適當(dāng)?shù)膭幽茼椣禂?shù),使標(biāo)量場在擾動下的穩(wěn)定性和哈勃常數(shù)的具體形式無關(guān)。
[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.
【學(xué)位授予單位】：廣西師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：P159

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本文編號：1563571