离散时空中的奇性自由的Friedmann宇宙解

由尘埃物质粒子的集合来形成一个理想的离散时空的Friedmann宇宙模型并证明了它是奇性 自由的. 关键词： 离散时空 尘埃物质 Friedmann宇宙 奇性自由     

尘埃粒子的时空结构及其性质

讨论了尘埃粒子解的时空结构及其性质，导出了尘埃粒子的内空间的离散结构.证明了尘埃粒子内部的物质球是一个无坐标的平直球，因而具有最小的体积和整体的关联性.导出了在尘埃粒子的内外时空中的径向测地线并说明其连续性.阐述了由这个解所揭示的物质、引力与时空之间的内在联系. 关键词： 尘埃粒子 离散时空 测地线     

离散时空中的非塌缩的尘埃球解

引进了实数的层次性与离散化，将连续函数理论加以改进和推广为离散函数理论，并基于由离散函数理论所表示的经典广义相对论来讨论尘埃物质的引力塌缩问题，指出了关于这个问题的连续体系的Oppenheimer 和Snyder解中的Friedmann内解与Schwarzschild外解的不完整性并加以拓展和离散化，导出了一种非塌缩的尘埃物质结构，消除了引力奇性并揭示了时空离散化的深刻性质. 关键词： 离散实数 离散时空 广义相对论 Oppenheimer 和Snyder解 奇性自由     

均匀密度零压星的完整的引力解

证明了Oppenheimer和Snyder关于均匀密度零压星的引力塌缩的经典解是不完整的,它并不能正确地连接作为内解和外解的Friedmann度规和Schwarzschild度规;通过在离散时空上拓展解参数而构成了一个完整的引力解,它实现了Friedmann度规和Schwarzschild度规之间的等价连接,并可以证明是奇性自由的;这个完整的引力解显示了物质,引力和离散时空结构之间的关联性 关键词： 均匀密度零压星 Friedmann度规 Schwarzschild度规 离散时空     

2006年诺贝尔物理学奖——宇宙微波背景辐射的黑体谱和各向异性

相传约137亿年前我们的宇宙起源于“盘古开天地式的大爆炸”，能量密度和温度均超高无比，却绝无什么特殊的“爆炸”中心，在足够大的尺度上均匀且各向同性，一直持续膨胀至今．刚开始的时候，随着宇宙温度的迅速降低，若干基本粒子物质相继浮现，宇宙早期的核合成过程制备形成了宇宙时空中第一代恒星形成之前的大致原初元素丰度分布．宇宙“大爆炸”发端时空中的能量场应当有量子涨落；耦合演化到后来呈现的物质场中，这些微弱而此起彼伏的涨落逐渐被引力在各种不同层次上放大，从而最终形成宇宙时空中不同尺度的物质结构系统（包括超星系团、星系团、星系、球状星团、恒星、行星等）．伴随着宇宙膨胀，有一个温度不断下降的热电磁辐射场被“捂”在物质场中；大约在389000年以后，这个热电磁辐射场基本不再与物质相互耦合作用，但它依然带有早期物质场中各处涨落的信息烙印．基于Einstein创立发展的广义相对论（1915年），Einstein（1917年）、Friedmann（1922年）、Lemaitre（1927年）、de Sitter（1932年）开辟了近代理论宇宙学的先河．Hubble（1929年）公布了遥远的星系退行速度正比于它们到我们的距离的划时代观测事实．基于宇宙元素丰度和核合成物理，Gamow，Alpher和Herman于1940—1950年大胆设想了宇宙“大爆炸”的物理框架图像．Penzias和Wilson（1964年）在贝尔试验室从事微波天线研究时意外地发现了2．7K宇宙微波背景辐射．经过多年的精心设计和准备，Mather和Smoot（1989—1994年）领导的“宇宙背景探索器”（COBE）空间试验精确地测量宇宙微波背景辐射的黑体谱和微弱的各向异性涨落；他们俩因此荣获2006年度的物理诺贝尔奖．90年来，科学家们众说纷纭，唇枪舌战，搜索证据，编造理论．随着地面、高空和空间综合试验及理论研究的持续迅速发展，精确宇宙学的时代已经到来．     

星系哈勃红移的非多普勒效应解释

分析了多普勒效应在解释星系哈勃红移现象时,星系际光传播过程存在的能量不守恒和宇宙膨胀时空不平权两大问题;提出了＂时空物质属性＂的3个基本假设;最后阐述了星系哈勃红移的非多普勒效应解释。     

典型时空中的运动效应和宇观红移现象

本文从相对性原理和局部光速不变性出发,建立了典型时空D_λ(1,4)的模型,讨论了其中的运动效应,计算了光谱线的频移,并在均匀分布的假定下与类星体N-Z关系的观测资料进行了比较。结果表明,河外天体的大红移可能主要不是由多普勒效应引起的,而在相当大程度上是典型时空中的距离效应。这样,运动群为SO(3,2)的模型D_λ<0(1,4)就可能是宇观时空较好的模写。     

Schwarzschild黑洞整体正规时空中的测地运动

本文研究了Schwarzschild黑洞整体正规时空中的测地运动,求得了无奇性内部时空中检验粒子测地方程的解析解,并与奇性黑洞情况作了比较。 关键词：     

Kiselev黑洞的热力学性质和物质吸积特性

本文考虑带有黑洞视界和宇宙视界的Kiselev时空.研究以黑洞视界和宇宙视界为边界的系统的热力学性质.统一地给出了两个系统的热力学第一定律;在黑洞视界半径远小于宇宙视界半径的情况下,近似地计算了通过宇宙视界和黑洞视界的热能.然后,探讨Kiselev时空的物质吸积特性.在吸积能量密度正比于背景能量密度的条件下给出黑洞的吸积率,讨论了黑洞吸积率与暗能量态方程参数的关系.     

关于相对论时空观念的局限性的问题

辩证唯物主义认识论认为:“理论是模写,是客观实在的近似的复写”.物理时空理论是关于不依赖于人的主观意识的客观的物质运动的存在形式的反映,这是唯物主义的根本观点;而任何具体的物理时空理论,就其正确反映客观的物质运动的存在形式来说,又不可避免地有它的近似性.人类对于客观真理的认识只能在无数相对真理的总和中实现. 其所以如此,原因之一是:空间和时间是物质运动的存在形式.而自然界各种事物是相互联系、相互作用的,这种相互作用构成了宇宙万物的运动与变化.但是,在具体研究特定范围的现象的时候,又不能不把它从普遍联系中抽象出来,…     

An attractor universe in six-dimensional N = 2 supergravity Kaluza-Klein theory

Cosmological solutions are investigated in six-dimensional, N = 2 supergravity Kaluza-Klein theory. It is shown that the solution of (the four-dimensional Friedmann universe)×(a constant S²) is the attractor, i.e. all the cosmological solutions starting from arbitrary initial conditions (apart from the time reversal ones) approach the above space-time asymptotically without any fine-tuning. The Friedmann solution is asymptotically “unique” in the later stage of the universe in six-dimensional N = 2 supergravity.     

Nonstatic axisymmetric universe model and its evolution

An axisymmetric rotating universe model is crossed with a time-dependent factor. Its evolution is studied. It turns out that for a particular choice it behaves exactly like that of a flat Friedmann universe.     

Brane-Cosmology Dynamics with Induced Gravity

The Friedmann equations for a brane with induced gravity are analyzed and compared with the standard general relativity and Randall-Sundrum cases. Randall-Sundrum gravity modifies the early universe dynamics, whereas induced gravity changes the late universe evolution. The early and late time limits are investigated. Induced gravity effects can contribute to late-universe acceleration. The conditions for this are found. Qualitative analysis is given for a range of scalar field potentials.     

Is the cosmological singularity thermodynamically possible?

The four broad approaches that have been suggested heretofore to eliminate the initial singularity from cosmology are briefly reviewed. None is satisfactory, basically because one does not know enough about the microphysics involved in the process. Thermodynamics has often been used in such dilemmas, and it is proposed to answer the question of whether there was a Friedmann-like singularity in the universe by exploiting the bound on specific entropy that has been established for finite system. It is made applicable to the universe by considering only a causally connected spacelike region within the particle horizon of a given observer. It is found that the specific entropy of radiation in such a region can exceed the bound if the observer is too early in the universe. Faith in the bound leads to the conclusion that the Friedmann models cannot be extrapolated back to nearer than a few Planck-Wheeler times from the singularity. The Friedmann initial singularity thus appears to be thermodynamically unacceptable.     

Classical and quantum cosmology with two perfect fluids: stiff matter and radiation

In this work the homogeneous and isotropic Universe of Friedmann–Robertson–Walker is studied in the presence of two fluids: stiff matter and radiation described by the Schutz’s formalism. We obtain to the classic case the behaviour of the scale factor of the universe. For the quantum case the wave packets are constructed and the wave function of the universe is found.     

De Broglie-Bohm Interpretation of Canonical Quantum Cosmology Implies Early Stages of the Universe Dominated by Radiation

The Einstein's general relativity is formulated in the Hamiltonian form for a spatially flat, isotropic and homogeneous universe. Subsequently, we perform the canonical quantization procedure to the Hamiltonian to obtain the Wheeler-DeWitt equation. Solving the Wheeler-DeWitt equation and employing the de Broglie-Bohm interpretation to the wave function of the universe, we obtain a new version of spatially flat Friedmann equation for the early universe where the scale factor of the universe is taken to be sufficiently small.     

Embedding of singularities

The Friedmann and Kantowski-Sachs models of the universe are embedded in eight-dimensional pseudo-Euclidean spaces in such a way, that their boundaries have the same structure as Geroch'sg-boundary.     

Shear in a perturbed Friedmann universe

For perturbed Friedmann models of vanishing and positive curvature the time development of shear is computed by means of a linear perturbation theory. As for the smallness of the perturbation functions mathematically exact and physically meaningful conditions are stated. The shear is computed for different stages of the universe.     

Holography and Non-Locality in a Closed Vacuum-Dominated Universe

A closed vacuum-dominated Friedmann universe is asymptotic to a de Sitter space with a cosmological event horizon for any observer. The holographic principle says the area of the horizon in Planck units determines the maximum number of bits of information about the universe that will ever be available to any observer. The wavefunction describing the probability distribution of mass quanta associated with bits of information on the horizon is the boundary condition for the wavefunction specifying the probability distribution of mass quanta throughout the universe. Local interactions between mass quanta in the universe cause quantum transitions in the wavefunction specifying the distribution of mass throughout the universe, with instantaneous non-local effects throughout the universe.