广义相对论中静态荷电球体的一组内解

本文在假定物质密度ρ_m=μr~α,电荷密度 ρ_e=ρ_0r~βe~(-λ/2)的情况下,严格求解 Einstein-Maxwell 场方程,得出了静态荷电球体的一组内解,把文[4]、[6]的结果作为自己的特例包括在内。     

广义相对论再经考验

爱因斯坦创立广义相对论已经93年了,但是由于它的某些预言（例如引力红移、引力波等）至今没有得到直接验证,科学家们仍在不断设计实验对它进行一轮又一轮“考验”。广义相对论预言,当两个大质量物体靠得很近时,会发出引力波,并使得它们自身的旋转轴产生摆动（物理学上称为“进动”）。人们已经观测到了这种摆动,只是还不足以精确测定其幅度大小。     

荷电(或荷磁)天体的引力效应

本文应用R-N度规,讨论了荷电(或荷磁)天体引力场对引力红移及雷达回波延时的影响。结果表明电荷(或磁荷)的作用使这两种效应减弱。     

关于DSX体系下的广义相对论（1PN）流体力学问题的探讨

使用ＤＳＸ 体系对于广义相对论（１ＰＮ） 的一般流体和理想流体均作了初步的探讨,建立了一种既适用于局部坐标系又适用于整体坐标系的解决广义相对论流体力学的新方法．对于一般流体,利用Ｍａｐｌｅ 软件计算了精确到ｃ－ ４ 项的能量动量张量Ｔａｂ 的结构,经过化简整理代到描述流体运动的基本方程中,得到了ＤＳＸ 体系下一般流体的基本方程,这是在局部坐标系中的结果,通过局部坐标和整体坐标之间的变换关系,可得整体坐标下物体的运动状态．另外,还给出了ＤＳＸ 体系下的理想流体力学的表示形式,通过将理想流体力学中一般的量改写为该体系下的量,从而改写了理想流体的Ｅｕｌｅｒ 方程和能量方程     

破解爱因斯坦的代码

科学家们正在计算机中模拟两个黑洞的碰撞,以便对爱因斯坦的相对论做最后的检验。 模拟两个黑洞的并合绝对是科学上的一次飞跃。一方面,它需要进行只有超级计算机才能胜任的大规模计算;另一方面,它还需要数值求解爱因斯坦广义相对论下用于描述两个黑洞及其运动的复杂方程。     

现代宇宙学的诞生

1,用广义相对论对宇宙所作的考查 爱因斯坦的相对论拓展了人类认识宇宙的视野,开始用物质的时空观来重新审视整个宇宙。物质的存在引起了时空的弯曲,也就是物质的分布决定？时空结构的非欧几甲德几何特性,而这种时空的弯曲等效于引力．所以对广义相对论引力场方程的求解,爱因斯坦建立了二十世纪第一个现代宇宙模型。     

活动星系核中心的双黑洞

不久前,《自然》杂志刊载文章介绍了一项包括中国在内的多国天文学家合作研究成果,证实活动星系核0J287中心存在双黑洞系统,并可由此检验爱因斯坦的广义相对论。OJ287属于一类特殊的活动星系核,它的亮度变化起伏不定,但变化周期却颇为准确。0J287正好处在黄道带上,许多专业和业余天文学家在搜寻彗星和小行星的时候会顺带观测它,因此他在光学波段的资料可以追溯到1890年。     

Charged Static Fluid Spheres in General Relativity

The work is concerned with the charged analogue of Bayin's paper (1978) related to Tolman's type astrophysically interesting aspects of stellar structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Tetrad Formulation of the Equations of Motion in General Relativity

It is shown that the equation of motion Du _j/Ds = (e/mc ²)F _ji u ⁱ , a natural generalization to the curved spacetime of the Heaviside-Lorentz law of ponderomotive force, is equivalent to the metric independent and covariant Van Dantzig's equations of motion dx ^j _[jpi] = 0 or L _v p _i = 0, where p _i is the conjugate momentum 4-vector and v a vector determined by the condition p _i v ⁱ, only with respect to holonomic coordinates. With respect to an anholonomic system, the Heaviside-Lorentz equation is a particular case of the VD equations valid for a privileged class of anholonomic frames, those consisting of orthogonal unit vectors.     

Notes on applications of General Relativity in free space

Varying the step, at which Lorentz signature is introduced in the scheme of applications of general relativity outside the material distribution, new solutions can be obtained. The interpretations of these solutions can be achieved if the field equations R_μv = 0 are written in a wider space than the Riemannian one. A counter example is given in favour of this claim.     

Gravitational Lensing Effects in a Modified General Relativity Model

We investigate the effects of gravitational lensing in a modified generalrelativity flat cosmological model. We show that the predicted lensingprobability for low matter densities is larger than in the Einstein-deSitter model but considerably less than in constant- models. Wealso find that the optical depth at low density rises with the sourcered-shift more slowly than in constant- models and that the lensdistribution peaks at lower values of the lens red-shift.     

Some Viscous Fluid Cosmological Models in General Relativity

The motivation of this paper is to investigate two viscous fluid cosmological models in General Relativity in which the expansion is only in two directions i.e. one of the Hubble parameters is zero. In the first model, coefficient of shear viscosity is assumed to be constant while in the second model, the coefficient of shear viscosity is proportional to the rate of expansion in the model. Here no additional condition is assumed except for coefficient of shear viscosity. These models are new and different from those models obtained by Bali and Jain (1987, 1988) in which free gravitational field was assumed to be Petrov Type D and non-degenerate for Marder (1958) metric and coefficient of shear viscosity is proportional to the rate of expansion in the model. The various physical and geometrical aspects of the models are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radiation hydrodynamics and Radiating Spheres in General Relativity

We comment on a method proposed to study the evolution of General Relativistic Radiating Spheres in both radiation limits, i.e. free streaming out and diffusion, extending it to handle any general radiating spherically symmetric distribution of matter. It is also shown that several dynamic models may emerge from a sole static equation of state. Previous erroneous calculations concerning this method are also commented.     

Magnetized Stiff Fluid Tilted Universe for Perfect Fluid Distribution in General Relativity

We have investigated magnetized stiff fluid Bianchi Type I anisotropic tilted cosmological model for perfect fluid distribution in General Relativity. It has been assumed that the expansion in the model is only in two directions i.e. one of the Hubble parameter (H₁ = A₄/A); is zero. It has been shown that tilted nature of the model is preserved due to magnetic field. The various physical and geometrical aspects of the model is also discussed.     

New concept for testing General Relativity: the Laser Astrometric Test Of Relativity (LATOR) mission

This paper discusses a Fundamental physics experiment that will test relativistic gravity at the accuracy better than the effects of the second order in the gravitational field strength, ∝ G². The Laser Astrometric Test Of Relativity (LATOR) mission uses laser interferometry between two micro‐spacecraft whose lines of sight pass close by the Sun to accurately measure deflection of light in the solar gravity. The key element of the experimental design is a redundant geometry optical truss provided by a long‐baseline (100 m) multi‐channel stellar optical interferometer placed on the International Space Station (ISS). The spatial interferometer is used for measuring the angles between the two spacecraft and for orbit determination purposes. In Euclidean geometry, determination of a triangle's three sides determines any angle therein; with gravity changing the optical lengths of sides passing close by the Sun and deflecting the light, the Euclidean relationships are overthrown. The geometric redundancy enables LATOR to measure the departure from Euclidean geometry caused by the solar gravity field to a very high accuracy. LATOR will not only improve the value of the parameterized post‐Newtonian (PPN) γ to unprecedented levels of accuracy of 1 part in 10⁸, it will also reach ability to measure effects of the next post‐Newtonian order (c⁻⁴) of light deflection resulting from gravity's intrinsic non‐linearity. The solar quadrupole moment parameter, J₂, will be measured with high precision, as well as a variety of other relativistic effects including Lense‐Thirring precession. LATOR will lead to very robust advances in the tests of Fundamental physics: this mission could discover a violation or extension of general relativity, or reveal the presence of an additional long range interaction in the physical law. There are no analogs to the LATOR experiment; it is unique and is a natural culmination of solar system gravity experiments. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Tilted Bianchi Type I Cosmological Models for Barotropic Perfect Fluid in General Relativity

In this paper, we have investigated that tilted Bianchi Type I cosmological models for stiff perfect fluid under a supplementary condition A = B ⁿ between metric potentials, is not possible. The tilted solution is also not possible when we assume A = t ^ℓ, B = t ^m , C = t ⁿ ; ℓ, m and n are constants for ε = p. Thus to preserve tilted nature of model, we assume p = γε, 0 ≤ γ ≤ 1 (barotropic equation of state) for the case A = t ^ℓ B = t ^m and C = t ⁿ . The physical and geometrical aspects of the models are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Impact of the Static Part of the Earth's Gravity Field on Some Tests of General Relativity with Satellite Laser Ranging

In this paper we calculate explicitly the classical secular precessions of the node and the perigee of an Earth artificial satellite induced by the even zonal harmonics of the static part of the geopotential up to degree l = 20. Subsequently, their systematic errors induced by the mismodelling in the even zonal spherical harmonics coefficients J _l are compared to the general relativistic secular gravitomagnetic and gravitoelectric precessions of the node and the perigee of the existing laser-ranged geodetic satellites and of the proposed LARES. The impact of the future terrestrial gravity models from CHAMP and GRACE missions is discussed as well. Preliminary estimates with the recently released EIGEN-1S gravity model including the first CHAMP data are presented.