共查询到19条相似文献,搜索用时 78 毫秒
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近年来,宇宙学领域,特别是现代宇宙学领域是十分活跃的。它的内容、它的发展趋势、它的哲学含义引起了越来越多的人的关注。这是因为,宇宙学既有长期的值得回顾的历史,又面临着实践进展所提出的全新问题。更重要的是,宇宙学从来就是意识形态上阶级斗争的场所,它总是同哲学宇宙观密切相关并受其指导的。宇宙学的发展史始终贯穿着唯物主义与唯心主义、辩证法与形而上学两种世界观的复杂、激烈的斗争。 相似文献
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解读宇宙的起源——2006年诺贝尔物理学奖简介 总被引:2,自引:0,他引:2
2006年度诺贝尔物理奖授予了在宇宙学研究领域取得杰出成果的美国科学家约翰·马瑟和乔治·斯穆特。他们发现的宇宙微波背景辐射的黑体谱和各向异性强烈地支持了大爆炸宇宙学模型并开启了“精确宇宙学”时代的大门。COBE之后宇宙学研究取得了一系列重大的进展。近年WMAP、SDSS等天文观测更加坚实有力地支持了大爆炸宇宙学模型,并对物理学提出了一些重大的、尖锐的挑战,诸如什么是暗物质?暗能量的物理本质是什么? 相似文献
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今年,Wilkinson微波背景各向异性探测器(WMAP)和Sloan数字巡天(SDSS)天文观测以其对宇宙学参数的精确测量,进一步强有力地支持了大爆炸宇宙学模型,这在人类探索宇宙奥秘和物质基本结构的道路上无疑是一个光辉的成就,这些精确测量推动了宇宙学的研究进入一个黄金时代,其发 相似文献
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学习研究宇宙物理的一本好教材──《宇宙学引论》评介李升今(邯郸师范专科学校物理系,邯郸056004)现代宇宙学是由爱因斯坦于1917年发表的题为《根据广义相对论对宇宙学所作的考查》一文揭开序幕的。从此,人们对字宙学的研究进人了一个新时代。近10年来,... 相似文献
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ZHA Chao-Zheng 《中国物理C(英文版)》1987,11(5):699-703
The cosmological term is necessaritly vanishing in a conformal gravitational theory, and the sum of the induced cosmological constants of all the brocken gauge symmetries cancels the curvature of the background spacetime. Thus the sum of all the cosmological constants is vanishing when the background spacetime is Minkowskian. Furthermore, the spontaneous breaking of a gauge symmetry through the Higgs mechanism is always accompanied by a phase transition of the background spacetime. 相似文献
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The influence of massive neutrino upon the clustering processes of cosmological matter in the early Jeans instabi-lity stage has been studied in the standard big bang theory. 相似文献
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The periodicity in the distribution of quasar redshifts is interprete dassuminq that the cosmological space is a topologi-cally compactified manifold like three-dimensional torus.The present size of such compact space is estimated at the order of 600Mpc. 相似文献
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The importance of cosmological constant for the cosmological models is given. The variations of the cosmological model for parameters λ and k were discussed respectively. Near λ = 0, the cosmological model is unstable with the change of λ, and near λ = β = 0, the cosmological model is unstable with the change of k. So when we consider the stable cosmological model, we must consider the nonzero cosmological constant. 相似文献
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Hrvoje tefan
i 《Physics letters. [Part B]》2009,670(4-5):246-253
The cosmological constant problem is studied in a two component cosmological model. The universe contains a cosmological constant of an arbitrary size and sign and an additional component with an inhomogeneous equation of state. It is shown that, in a proper parameter regime, the expansion of the universe with a large absolute value of the cosmological constant may asymptotically tend to de Sitter space corresponding to a small effective positive cosmological constant. It is argued that such a behavior can be regarded as a solution of the cosmological constant problem in this model. The mechanism behind the relaxation of the cosmological constant is discussed. A connection with modified gravity theories is discussed and an example of a possible realization of the cosmological constant relaxation in f(R) modified gravity is described. 相似文献
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We investigate the locally rotationally symmetric (LRS) Bianchi type-I cosmological model for stiff matter and a vacuum solution with a cosmological term proportional to R-m (R is the scale factor and m is a positive constant). The cosmological term decreases with time. We obtain that for both the cases the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term. 相似文献
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T. Padmanabhan 《Physics Reports》2003,380(5-6):235-320
Recent cosmological observations suggest the existence of a positive cosmological constant Λ with the magnitude Λ(G/c3)≈10−123. This review discusses several aspects of the cosmological constant both from the cosmological (Sections 1–6) and field theoretical (Sections 7–11) perspectives. After a brief introduction to the key issues related to cosmological constant and a historical overview, a summary of the kinematics and dynamics of the standard Friedmann model of the universe is provided. The observational evidence for cosmological constant, especially from the supernova results, and the constraints from the age of the universe, structure formation, Cosmic Microwave Background Radiation (CMBR) anisotropies and a few others are described in detail, followed by a discussion of the theoretical models (quintessence, tachyonic scalar field, …) from different perspectives. The latter part of the review (Sections 7–11) concentrates on more conceptual and fundamental aspects of the cosmological constant like some alternative interpretations of the cosmological constant, relaxation mechanisms to reduce the cosmological constant to the currently observed value, the geometrical structure of the de Sitter spacetime, thermodynamics of the de Sitter universe and the role of string theory in the cosmological constant problem. 相似文献