【摘要】： 宇宙學(xué)標(biāo)準(zhǔn)模型在物理學(xué)的發(fā)展中扮演著重要的角色,因?yàn)樗A(yù)言了一系列關(guān)于宇宙演化的理論結(jié)果,而這些結(jié)果被隨后的觀測(cè)所證實(shí)。然而,標(biāo)準(zhǔn)模型中也存在著許多問(wèn)題在理論上無(wú)法給出合理的解釋。通過(guò)引入暴脹假說(shuō),某些問(wèn)題如視界疑難、平直性疑難以及磁單極子疑難等得到或部分得到解決。與此不同的是,另一些問(wèn)題如大爆炸奇點(diǎn)問(wèn)題,暗能量問(wèn)題以及宇宙大尺度結(jié)構(gòu)的起源和形成等問(wèn)題一般認(rèn)為純粹在經(jīng)典引力論的框架內(nèi)是無(wú)法給出圓滿(mǎn)解決的方案的。 本文首先簡(jiǎn)單地回顧了標(biāo)準(zhǔn)宇宙理論和暴脹模型的基本內(nèi)容,然后主要介紹了大爆炸奇點(diǎn)和幾類(lèi)半經(jīng)典量子宇宙學(xué)中給出的解決方案。 其次,我們通過(guò)引入一個(gè)特殊的修正色散關(guān)系研究了它對(duì)宇宙的背景動(dòng)力學(xué)的影響。通過(guò)引力理論與視界上的熱力學(xué)的一種對(duì)應(yīng),我們推導(dǎo)出了一個(gè)含有反彈解的修正的弗里德曼方程。然后探討了產(chǎn)生反彈所需的條件和可能性,我們發(fā)現(xiàn)在高能區(qū)域,當(dāng)粒子能量趨近于普朗克能標(biāo)時(shí),大反彈的確能夠產(chǎn)生。因此,在我們的模型里大爆炸奇點(diǎn)問(wèn)題不復(fù)存在。 在第三部分,我們首先回顧了宇宙早期熱擾動(dòng)假說(shuō)的一些基本內(nèi)容,比如熱功率譜的計(jì)算以及非高斯性的相關(guān)簡(jiǎn)介。此后我們也簡(jiǎn)單地回顧了三類(lèi)比較流行的半經(jīng)典模型中熱擾動(dòng)的研究情況,這些模型的引入使得標(biāo)準(zhǔn)宇宙學(xué)中無(wú)法得到譜的標(biāo)度不變性的困難得以克服。最后,我們研究了熱擾動(dòng)在粘滯宇宙中的情況。我們發(fā)現(xiàn),由于粘滯性的存在,各種熱擾動(dòng)模在穿越視界以后的演化行為將與理想流體時(shí)的情況很不一樣。這樣,標(biāo)準(zhǔn)模型中的困難被打破,當(dāng)粘滯流體的狀態(tài)參量滿(mǎn)足w≈α-1或是w≈-1/3的時(shí)候,我們得到的功率譜是標(biāo)度不變的。同時(shí),我也討論了擾動(dòng)的非高斯性。我們發(fā)現(xiàn),對(duì)于德西特膨脹,即狀態(tài)參數(shù)滿(mǎn)足w≈α-1時(shí),非高斯性被壓低；而對(duì)于phantom like w≈-1/3的情況,如果我們選取粘滯系數(shù)α≈4/3,則非高斯性具有標(biāo)度不變性且是可以被觀測(cè)到的。
[Abstract]:The standard cosmological model plays an important role in the development of physics because it predicts a series of theoretical results on the evolution of the universe, which are confirmed by subsequent observations. However, there are many problems in the standard model which can not be explained in theory. By introducing the inflation hypothesis, some problems such as horizon problem, flatness problem and magnetic monopole problem are solved or partially solved. In contrast, other problems, such as the singularity of the Big Bang problem, the dark energy problem and the origin and formation of the large-scale structure of the universe, are generally considered to be impossible to give a satisfactory solution purely within the framework of classical gravitation theory. In this paper, the basic contents of the standard cosmic theory and the inflation model are briefly reviewed, and then the solutions of the Big Bang singularity and several kinds of semi-classical quantum cosmology are introduced. Secondly, we study its influence on the background dynamics of the universe by introducing a special modified dispersion relation. By means of a correspondence between the theory of gravity and thermodynamics on the horizon, we derive a modified Friedman equation with a bouncing solution. Then we discuss the conditions and the possibility of producing the rebound. We find that in the high energy region, when the particle energy approaches the Planck energy scale, the large rebound can indeed occur. Therefore, the big bang singularity problem no longer exists in our model. In the third part, we first review some basic contents of the early cosmic thermal disturbance hypothesis, such as the calculation of thermal power spectrum and the introduction of non-Gao Si. After that, we also briefly review the study of thermal perturbation in three popular semi-classical models. The introduction of these models makes it possible to overcome the difficulty of scale invariance of spectrum in standard cosmology. Finally, we study the thermal perturbation in the viscous universe. It is found that due to the existence of viscosity, the evolution behavior of various thermal disturbance modes after crossing the horizon will be very different from that of the ideal fluid. In this way, the difficulty in the standard model is broken. When the state parameters of the viscous fluid satisfy w 鈮，

本文編號(hào)：2254030