高导数引力理论宇宙动力学方程

利用高导数引力理论研究宇宙的演化.在Friedmann宇宙模型中,由高导数场方程导出宇宙动力学方程.此方程为宇宙标度因子关于时间的三阶非线性微分方程,并由能量-动量守恒及物态方程导出能量密度和宇宙标度因子的关系,最后比较了高导数引力理论动力学方程和标准动力学方程.

宇宙动力——把人类送入远天

人类探索宇宙空间的难题是寻找一种有效的推力 ,这种推力必须强劲无比 ,可源源不断地供应。本文介绍了世界上正在研究中的几种可能的动力技术 ,分别是激光、微波、太阳能、等离子体和磁悬浮技术。有的技术已经成熟 ,有的已有起色 ,在不久的将来必将为人类探索星际所运用。

光子、热力学与膨胀宇宙

基于宇宙学观测以及含宇宙常数的广义相对论场方程建立的标准宇宙模型,存在着违背物理学基本规律的疑难,提示我们需要仔细审视宇宙动力学的物理基础.例如,同实物退耦后的背景黑体辐射光子数目不再随宇宙膨胀而变化,但宇宙学红移效应导致辐射温度反比于宇宙尺度下降,则背景辐射总能量也反比于宇宙尺度而不断减少,违背了热力学第一定律,损失的宇宙背景辐射能量到哪里去了?又如,宇宙常数对应的暗能量密度不随时间变化,膨胀宇宙中物质不断被创生,总能量随宇宙膨胀趋于无穷.在宇宙学中坚持能量守恒,需要限制暗物质和暗能量的基本物理性质,其中作为零质量玻色子的光子扮演着重要角色.基于爱因斯坦场方程同时又不放弃能量守恒定律的宇宙学模型,给出了和标准模型完全不同因而可以被观测证实或证伪的演化图景:暗物质同暗能量平衡状态下的匀速膨胀才是宇宙的常态,而减速或加速膨胀只是宇宙介质相变导致的瞬态过程.近期开始出现的高精度宇宙学观测结果对标准模型提出了挑战,而有利于能量守恒宇宙模型的预期.正在进行和计划中的宇宙学观测将最终判定2类模型,并且推动基本物理的发展.

苏联科技人才外流严重

苏联是个科技大国,在微粒子固体材料合成、合成材料、稀土元素等领域苏联处于世界领先地位。另外,苏联的宇宙动力学、原子动力学、爆炸焊接、高频无线电蓄电池、脉冲能源和现代陶瓷生产等方面都达到了极高的水平。多年来,苏联培养出大量科技人才,高峰时其人数几乎占了世界科技人员总数的1/4。但是,近年来苏联科技人才外流情况严重。仅1989年苏联外流的科技人才就达7万多,主要流向美国。过去20年美国有半数人才来自苏联。苏联科学院系统各研究单位外流人才中20％在美国落户。苏联流向美国的科技人才给美国带来巨大的好处。

Automatic Organization, Thinking Motion and Dynamics of the Universe

There are many automatic organization phenomena and automatic organization unities in the universe. The automatic organization whole refers to a life body with the thinking. The thinking is the core of automatic organization. The thinking is at eternal restless motion and binds to substances. The universe, organism and society are the automatic organization unities or life systems with the thinking. The thinking can perceive, attract, drive, organize and control all individuals and it is a force of life structure or universal gravitation and universal repulsion. The thinking has a life structure, a template and dynamic of entity-life＇s automatic organization. Life body has five dynamic systems： the thinking motion and information flow, breathing motion, closed-loop current （particle flow） and energy flow, interaction among state-varying, state-stabilizing and control organizations and active ＆ automatic chemical-physical reactions, cardiac pulsation and active motion and transportation. Human, galaxies and society can change from low to high energy state initiatively. This is realized by controlling the desires of life entity via the thinking and breathing motions and by altering the body＇s binding forces dominating the life entity （in turn, by bond force, strong interaction and quark confinement）. All forces in the universe present in the universe of life： force of the thinking-universal gravitation and universal repulsion, electromagnetic interaction, bond force, strong interaction, quark confinement and weak interaction. Under the automatic organization of the thinking, these forces bind into a 4-season＇ whole. The united state of these forces is controlled by the thinking and breathing motion, which is capable of changing from 3-, 2- and 1-dimensional states to a 0-dimensional state.

Metric Expansion from Microscopic Dynamics in an Inhomogeneous Universe

Theories with ingredients like the Higgs mechanism, gravitons, and inflaton fields rejuvenate the idea that relativistic kinematics is dynamically emergent. Eternal inflation treats the Hubble constant H as depending on location. Microscopic dynamics implies that H is over much smaller lengths than pocket universes to be understood as a local space reproduction rate. We illustrate this via discussing that even exponential inflation in TeV-gravity is slow on the relevant time scale. In our on small scales inhomogeneous cosmos, a reproduction rate H depends on position. We therefore discuss Einstein-Strauss vacuoles and a Lindquist-Wheeler like lattice to connect the local rate properly with the scaling of an expanding cosmos. Consistency allows H to locally depend on Weyl curvature similar to vacuum polarization. We derive a proportionality constant known from Kepler＇s third law and discuss the implications for the finiteness of the cosmological constant.

Regular Black Holes with Cosmological Constant

We present a class of regular black holes with cosmological constant A in nonlinear electrodynamics. Instead of usual singularity behind black hole horizon, all fields and curvature invariants are regular everywhere for the regular black holes. Through gauge invariant approach, the linearly dynamical stability of the regular black hole is studied. In odd-parity sector, we find that the A term does not appear in the master equations of perturbations, which shows that the regular black hole is stable under odd-parity perturbations. On the other hand, for the even-parity sector, the master equations are more complicated than the case without the cosmological constant. We obtain the sufficient conditions for stability of the regular black hole. We also investigate the thermodynamic properties of the regular black hole. and find that those thermodynamic quantities do not satisfy the differential form of first law of black hole thermodynamics. The reason for violating the first law is revealed.

Cosmological Models with Fractional Derivatives and Fractional Action Functional

Cosmological models of a scalar field with dynamical equations containing fractional derivatives or derived from the Einstein-Hilbert action of fractional order, are constructed. A number of exact solutions to those equations of fractional cosmological models in both eases is given.

她“生命的形式”是这样的——访广东亚视演艺学院副院长“广现”创始人杨美琦

杨美琦是位既有眼光又有抱负的舞蹈教育家,更是位性格独具、毅力过人,只要她看准的目标、认定的理想,不达目的决不轻言放弃的人。在现代舞这块领地上她捷足先登,义无反顾,不仅首创了广东舞校现代舞实验班,还于1992年首创了广东实验现代舞团,为当今中国现代舞事业写下了辉煌的一笔。她任该团团长8年。

Measuring accelerating universe with high-redshift GRBs data and other cosmological probes

A kinematical model （a parameterized deceleration parameter） and a dynamical model （a parameterized equation of state for dark energy） are constrained from the current observational data including the high-redshift Gamma-Ray Bursts （GRBs） data with a redshift range from 1.4 to 9. We obtain the stringent constraint on the values of current deceleration parameter q0, current jerk parameter j0, current equation of state for dark energy Woae and transition redshift zT. In addition, we compare the difference of the constraint results between the kinematical and the dynamical scenarios.

Diagnosing ΛHDE model with statefinder hierarchy and fractional growth parameter

Recently, a new dark energy model called AHDE was proposed. In this model, dark energy consists of two parts： cosmological constant A and holographic dark energy （HDE）. Two key parameters of this model are the fractional density of cosmological constant Ω2A0, and the dimensionless HDE parameter c. Since these two parameters determine the dynamical properties of DE and the destiny of universe, it is important to study the impacts of different values of ΩA0 and c on the AHDE model. In this paper, we apply various DE diagnostic tools to diagnose AHDE models with different values of ΩA0 and c; these tools include statefinder hierarchy {S3^（1） ,S4（1）fractional growth parameter E, and composite null diagnostic （CND）, which is a combination of{S3（1）,S4（1）} and E. We find that： （1） adopting different values of ΩA0 only has quantitative impacts on the evolution of the AHDE model, while adopting different c has qualitative impacts; （2） compared with S（1）, S（41） can give larger differences among the cosmic evolutions of the AHDE model associated with different ΩA0 or different c; （3） compared with the case of using a single diagnostic, adopting a CND pair has much stronger ability to diagnose the AHDE model.

Analysis of Generalized Ghost Dark Energy in LQC and Galileon Gravity

A so-called ghost dark energy was recently proposed to explain the present acceleration of the universe.The energy density of ghost dark energy,which originates from Veneziano ghost of Quantum Chromodynamics(QCD),in a time dependent background,can be written in the form,ρD=αH + βH^2 where H is the Hubble parameter.We investigate the generalized ghost dark energy(GGDE) model in the setup of loop quantum Cosmology(LQC) and Galileon Cosmology.We study the cosmological implications of the models.We also obtain the equation of state and the deceleration parameters and differential equations governing the evolution of this dark energy model for LQC and Galileon Cosmology.

Anisotropic Bianchi Type Ⅰ Cosmological Models with Generalized Chaplygin Gas and Dynamical Gravitational and Cosmological Constants

This paper deals with study of generalized Chaplygin gas model with dynamical gravitational and cosmological constants. In this paper a new set of exact solutions of Einstein field equations for spatially homogeneous and anisotropic Bianchi type Ⅰ space-time have been obtained. The solutions of the Einstein's field equations are obtained by considering(i) the power law relation between Hubble parameter H and scale factor R and(ii) scale factor of the form R =-1/t + t^2, t > 1. The assumptions lead to constant and variable deceleration parameter respectively. The physical and dynamical behaviors of the models have been discussed with the help of graphical representations. Also we have discussed the stability and physical acceptability of solutions for solution type-Ⅰ and solution type-Ⅱ.

Tachyon Cosmology with Gauss–Bonnet and Non-Minimal Kinetic Couplings

We consider a tachyonic model of dark energy in which scalar field non-minimally coupled with curvature and kinetic part of its Lagrangian density.Additionally the model contains the Gauss–Bonnet coupling to the scalar field through an arbitrary function.The non-minimal Gauss–Bonnet coupling function and scalar field potential have been obtained for power-law solution and then for a dynamically varying equation of state.We have extracted the required condition for the so-called phantom divide line crossing in the model and represented such a crossing numerically.

Energy budget of cosmological first-order phase transition in FLRW background

We study the hydrodynamics of bubble expansion in cosmological first-order phase transition in the Fdedmann-LemMtre- Robertson-Walker （FLRW） background with probe limit. Different from previous studies for fast first-order phase transition in flat background, we find that, for slow first-order phase transition in FLRW background with a given peculiar velocity of the bubble wall, the efficiency factor of energy transfer into bulk motion of thermal fluid is significantly reduced, thus decreasing the previously-thought dominated contribution from sound wave to the stochastic gravitational-wave background.

Effects of f(R) Model on Dynamics of Axial Shear-Free Dissipative Fluids

We present a general analysis on non-static axial system with dissipative shear-free anisotropic fluid using polynomial inflationary f(R) model.We study the effects of dissipation on the dynamics of geodesic matter distribution.This leads the system either to rotation-free or expansion-free but not both simultaneously under geodesic condition.It is found that the system preserves its symmetry in both cases.For the rotation-free case,when there is no dissipation and Ricci scalar is constant,the axial system reduces to FRW universe model.This is exactly the same result obtained in general relativity.

Anisotropic Inflationary Scenario Via Generalized Chaplygin Gas Model

We investigate generalized chaplygin gas for warm inflationary scenario in the context of locally rotationally symmetric Bianchi type I universe model.We assume two different cases of dissipative coefficient,i.e.,constant as well as function of scalar field.We construct dynamical equations as well as a relationship between scalar and radiation energy densities under slow-roll approximation.We also derive slow-roll parameters,scalar and tensor power spectra,scalar spectral index,tensor to scalar ratio for analyzing inflationary background during high dissipative regime.We also use the WMAP7 data for the discussion of our parameters.