Energy momentum pseudo-tensor of high frequency gravitational waves and their dynamical back-reaction

To describe properties of the high frequency gravitational wave （HFGW） propagating through the vacuum gravitational field in Robertson-Walker background space-time, we calculated its energy momentum pseudo-tensor （EMPT） in the limit of short wavelengths by taking the Brill-Hartle average on the second order perturbation of the Einstein tensor over several wavelengths. By rewriting the EMPT as a form of perfect fluid, the dynamical back-reaction of HIFGW on the background spacetime was discussed. The result shows that the energy density of HFGW, which is in the gauge we chose, is positive definite. The HFGW serves as a source for curving the background space-time and affects the dynamical evolution and time evolution of the scale factor of the Robertson-Walker metric.     

强激光脉冲产生的引力法拉第效应

1Introduction Generalrelativityisthetheoryofstudyinggravita tionandthestructureofspace time.Sinceitsestab lishment,ithasbeenattractinginterestsoftheoreti cians.However,thereislittleobservableandexperi mentalexaminationshowingthefeaturesoflarge scale structureofspace time.Withtechnologicaladvances, severalgravitationaleffectswereinvestigatedsuchas gravitationalwavetest,starkeffect,gravitationallens effect,gravitationalFaraday,etc.Inthispaperwe discussgravitationalFaradayeffect. Itiswellkn…     

重力场中理想气体的位能热循环及热功转化

在重力场密闭于刚性容器中的气体密度随高度而减小,且气体的位能随温度而变化．利用密闭容器中的气体位能热循环可实现“热一功”转化过程,该循环有别于传统的卡诺循环（本文称其为“位能循环”）．进一步分析及总结出重力场中理想气体的位能热循环的熵变化计算方法．     

反绝热近似下金属络合物链的二聚化行为

运用玻色化方法研究了一维半充满状态的金属络合物的基态和激发态在反绝热近似下的临界性质.结果表明在反绝热情况下系统的基态是电荷密度波相，其电荷密度波相的强度随电声耦合参量的变化而变化.同时也讨论了系统二聚化序参量的变化规律.     

单一弹性常数近似下向错线对二维液晶自由能的贡献

In light of the Ф-mapping method,the contribution of disclination linges to the free energy density of 2-dimensional liquid crystals is studied in the single-elastic constant approximation.It is pointed out that ,compared with the previous theory ,the free energy density can be divided into two parts.One is the usual distorted energy density of director field around the disclination lines.The other is the free endrgy density of the disclination lines themselves which is centralized at the disclination lines and topoligically quantized in a unit of 1/2kπ .The topological quantum numbers are determined by the Hopf indices and Brouwer degrees of the director field at the disclination lines,i.e.,the disclination strength.From the method of Lagrangian multipliers,the equilibrium equation and the molecular field of 2-dimensional liquid crystals are also obtained.It is shown that the physical meaning of the Lagrangian multiplier is just the distorted energy density.     

场源参量对引力红移效应的影响

讨论了场源的电（磁）荷、角动量、旋转电荷和磁短对引力红移效应的影响。结果表明,电（磁）荷、角动量和磁矩均使这种效应减弱,旋转电（磁）荷使这种效应增强。     

零静止质量磁偶极子的引力场问题

运用Einstein-Maxwell方程组对具有零静止质量的磁偶有子引力场问题进行了研究,然后在磁场近似下对所得结论作以讨论。     

电荷-能量联系定律的论证

根据质量、电荷的起源和作用．并从牛顿定律的普适性和万有引力及库仑力场做功的等效性两种方法出发，定义和推导出电荷质量当量值，从而得出电荷一能量联系定律。     

论惯性质量与引力质量

物理学中,质量通常是用来指物质的性质,在实验上,两种质量（惯性质量和引力质量）是一致的。因此牛顿力学中并没有对惯性质量和引力质量进行严格的区分。两种质量的等效性通常被称为伽利略等效原理或弱等效原理。爱因斯坦从这一原理出发,得到了广义相对论,明确指出这两者的一致性不是偶然的。本文论述了两者在牛顿力学里的表现和出现的困难,进一步讨论了惯性质量和引力质量在爱因斯坦理论中的统一,最后提出二者的等效性需要等待广义相对论正确性的最终确认。     

流体中对流现象的研究(英文)

本文讨论了在重力场作用下流体平衡的稳定性条件 ,如果这一稳定性条件被打破 ,对流将会发生 ;其次 ,还讨论了地球对流层中气压及密度与海拔的关系     

低能光子的量子引力“遗迹”效应

量子引力理论是人类在探索自然界四种基本相互作用统一的道路上的终极目标。其中不少候选理论预言了在低能区的可观测效应,称为量子引力＂遗迹＂效应。本文讨论了量子引力理论对于低能区的光子色散关系的修正,和由此带来的可观测后果,以及现今实验观测上的检验与约束。     

"万有引力场强度"与"万有引力场的高斯定理"

通过库仑定律与万有引力定律的相似之处．由静电场的电场强度和静电场的高斯定理引入万有引力场强度和万有引力场的“高斯定理”,在求解某些具有对称性物体与质点之间的万有引力时,通过万有引力场的“高斯定理”可以大大简化计算．     

广义相对论的几何纲领与引力场的时空特性

在GR中,引力场各处的时钟快慢不同,引力场中各处的量杆长短不同,但是,引力场中的光速却是不变的.这意味着引力场时空弯曲了,欧几里德几何规律不再成立.其根本原因正是爱因斯坦所开创的广义相对论的几何化纲领.     

人工与天体引力波源

引力波是广义相对论的重要推论之一。科学家们希望能直接探测到引力波,但是由于产生机制的不同,引力波远弱于电磁波,而人工引力波源产生的引力波目前无探测可能。宇宙中虽然存在大量的天体引力波源,但传到地球上的信号都很弱。目前,科学家们已设计出几种实验装置去探测引力波。     

引力场对天文观测的影响

由于引力场的存在,恒星或其它星系在宇宙中的分布并不完全象我们现在所看到的情形,有些天体并非真正位于我们在天文望远镜中所观察到的位置,是引力场帮助我们揭示了它们的存在。     

从场论角度理解引力场的特性

本文将引力场的梯度、散度和旋度与静电场相应的三量进行了对比,从场论的角度对引力场的属性加以描述,加深了对引力场特征的认识。     

Gravity defied from potato asteroids to magnetised neutron stars

A star burns its nuclear fuel and balances gravitation by the pressure of the heated gas, during its active lifetime. After the exhaustion of the nuclear fuel, a low mass starfinds peace as a ‘white dwarf’, where the pressure support against gravitation is provided by Fermi-degenerate electrons. However, for massive stars, the gravitational squeeze becomes so severe that in the final phase of evolution, the average density approximately equals the nuclear density. At such densities, most of the protons combine with electrons to convert themselves into neutrons. A ‘neutron star’, composed of such neutron-rich material, is host to some fascinating physics arising out of its amazingly compact state of matter (where a solar mass is packed inside a sphere of radius ~ 10Km).     

引力场中电磁波的传播和光线偏折

The gauge invariance of the electromagnetic field in gravitational field is an important question. We prove d' Alembert equation in gravitational field with gauge invariance under the Lorentz condition. Using the kinematic equation of photon in normal static and spherically symmetric gravitational fields, we deduce the orbital equation of photon. As a special example, we explicate the deduction and discussion about the deviation angular of light in Reissner-Nordstrom space-time.     

A special fermionic generalization of lineal gravity

INTRODUCTION The models of lineal gravity (the gravity theory in (1 1)-dimensions) are Liouville theory (Jackiw, 1985), a simplest non-trivial theory based on the sca- lar curvature R and additional scalar field, and so-called ‘string-inspired’ model (Cangemi and Jackiw, 1992; 1993), where scalar (dilaton) field arises from the string theory. Both models can also be obtained by dimensional reduction from (2 1)-di- mensions (Achúcarro, 1993; Cangemi, 1992; Grig- nani and Nardelli, 19…     

温度对重力场中粒子数按高度分布律的影响

应用比较法,通过分析和计算,定义了重力场中粒子数按高度分布律的分界高度和分界温度概念,并给出了其定量公式.在此基础上,对重力场中粒子数按高度分布律受气体温度的影响规律给出了简明和特征性的说明.