On the Possibility to Construct Gravitational Eye

The possibility of modifying a conventional Cavendish torsion pendulum into a half-armed pendulum oscillator to measure the horizontal gravitational acceleration is discussed. A new kind of gravitational detector, gravieye, as we named, can be made by a proper combination of such oscillators to ＂see＂ remote objects and to be used, e.g. to detect the movement of huge mass at a long distance.     

ESSAY: The Cosmological Constant Problem in Brane-Worlds and Gravitational Lorentz Violations

Brane worlds are theories with extra spatial dimensions in which ordinary matter is localized on a (3+1) dimensional submanifold. Such theories could have interesting consequences for particle physics and gravitational physics. In this essay we concentrate on the cosmological constant (CC) problem in the context of brane worlds. We show how extra-dimensional scenarios may violate Lorentz invariance in the gravity sector of the effective 4D theory, while particle physics remains unaffected. In such theories the usual no-go theorems for adjustment of the CC do not apply, and we indicate a possible explanation of the smallness of the CC. Lorentz violating effects would manifest themselves in gravitational waves travelling with a speed different from light, which can be searched for in gravitational wave experiments.     

Bound on the Q-Factor of a G-Constant Measuring Pendulum Device from Gravitational Stochastic Background

We discuss the possible effects of gravitational-wave stochastic background on the performance of a pendulum device such those used in precise measurements of the gravitational constant G. The variation Q of the quality factor Q of the pendulum induced by the stochastic background is evaluated, by using as numerical input the results obtained in gravitational antennas experiments. It is found |q|10^–10, completely negligible with respect to a typical value Q10⁵.     

实验检验光子静止质量的研究进展

爱因斯坦狭义相对论的基本假设之一是光速不变性,其直接推论就是光子的静止质量必须为零,因此实验检验光子是否具有非零的静止质量一直备受关注.非零光子静止质量以Proca方程组为基础,其实验检验主要针对真空光速(频率)色散效应、库仑反平方定律和安培环路定律的偏离、寻找纵向电磁波以及磁偶极场的Yukawa势等几个方面.文章作者所在的实验小组采用精密扭秤调制方法将国际上同类实验结果提高了2个数量级,给出光子静止质量上限为mγ≤1.5×10-52g.对光子静止质量的实验检验,也是对光速不变原理的一种检验,即使光子仅有非常微小的静质量,如一旦得到实验的检验,将会对整个物理学的发展产生巨大而深刻的影响.     

实验检验光子静止质量的研究进展

爱因斯坦狭义相对论的基本假设之一是光速不变性,其直接推论就是光子的静止质量必须为零,因此实验检验光子是否具有非零的静止质量一直备受关注.非零光子静止质量以Proca方程组为基础,其实验检验主要针对真空光速（频率）色散效应、库仑反平方定律和安培环路定律的偏离、寻找纵向电磁波以及磁偶极场的Yukawa势等几个方面.文章作者所在的实验小组采用精密扭秤调制方法将国际上同类实验结果提高了2个数量级,给出光子静止质量上限为mγ≤1.5×10-52g.对光子静止质量的实验检验,也是对光速不变原理的一种检验,即使光子仅有     

用Excel研究单摆测重力加速度实验中的随机误差分布规律

在单摆法测重力加速度实验中,为了能够快速且正确地得到摆球运动周期的随机误差分布规律,本文提出了一种应用Excel软件给出随机误差统计直方图的方法。该方法简单直观,能够加深同学对随机误差统计规律的认识。     

Quantum Nondemolition Measurements of a Particle in an Inhomogeneous Gravitational Field

In this work we obtain a family of quantum nondemolition variables for the case of a particle moving in an inhomogeneous gravitational field. Afterwards, we calculate the corresponding propagator, and deduce the probabilities associated with the possible measurement outputs. The comparison, with the case in which the position is being monitored, will allow us to find the differences with respect to the case of a quantum demolition measuring process.     

The Cosmological Constant in the Framework of Gravito-Magnetodynamic Waves in Weak Gravitational Fields

Using the linearization of Einstein's equations for weak gravitational fields, a specific model of gravito-magnetofluid is elaborated. The study of wave formation and propagation in such a medium is necessarily connected to the existence of the cosmological constant.     

万有引力常数G精确测量实验进展

万有引力常数G是人类历史上引入的第一个基本物理学常数,其在理论物理、天体物理和地球物理等许多领域中扮演着重要角色.两百多年来,人们共测量出了200多个G值,但G的测量精度仍然是所有物理学常数中最差的,这一现象反映了测G工作本身的复杂性和困难性.本文简要概述了G值测量的意义和测G的历史,并结合自2010年以来国际上新出现的三个高精度测G实验介绍这一领域的研究进展,以及华中科技大学引力实验中心测G工作的最新动态.     

惯性质量与引力质量相等的实验验证

设计了一套实验装置,以此研究了物质惯性质量与引力质量的等价性.与以往伽利略自由落体实验和牛顿单摆实验等动态验证法相比,本实验以静态的方式进行,大大减少了机械摩擦和空气阻力,又通过扭秤的光学系统将微弱作用力放大,因而实验的精度可高达,精确地验证了物质惯性质量与引力质量的等价性,填补了国内相关方面研究的空白.     

Constant of Motion,Lagrangian and Hamiltonian of the Gravitational Attraction of Two Bodies with Variable Mass

The Lagrangian, the Hamiltonian and the constant of motion of the gravitational attraction of two bodies when one of them has variable mass is considered. The relative and center of mass coordinates are not separated, and choosing the reference system in the body with much higher mass, it is possible to reduce the system of equations to 1-D problem. Then, a constant of motion, the Lagrangian, and the Hamiltonian are obtained. The trajectories found in the space position-velocity,(x,v), are qualitatively different from those on the space position-momentum,(x,p). PACS numbers: 03.20.+i     

Precise measurement of the depolarization ratio from photoacoustic Raman spectroscopy

A new method for the accurate determination of the Raman depolarization ratio is reported with an improved setup for photoacoustic Raman spectroscopy (PARS). The precise measurement is achieved by measuring the dependence of the acoustic signal intensity on the cross‐angle between the polarizations of two incident laser beams. We demonstrate this sensitive and simple method with several gaseous molecules, such as CH₄ and H₂. The measured results of depolarization ratios agree well with the theoretical values with an upper error limit of ± 0.005, which is comparable to that with polarization‐resolved CARS spectroscopy. Copyright © 2007 John Wiley & Sons, Ltd.     

一种基于CCD的实时测量光栅常数的方法

光栅常数是检验光栅质量的重要参数之一.该文介绍了一种实时检测光栅参数的方法,即利用面阵CCD采集光栅衍射图像信息,通过计算衍射±1级光斑与主极大光斑的能量比得出光栅常数.这种方法具有检测速度快、系统简单、精度高等特点,可用于生产线上光栅的实时检测.     

德拜相法测晶格常数实验数据处理方法分析简

数据处理是大学物理实验中的一个重要环节。本文介绍了德拜相法测晶格常数实验中的三种数据处理方法,通过误差分析提出了提高准确度的方向,为解决实验教学中存在问题提供了依据。     

干涉法测量非球面顶点半径和二次常数

非球面顶点半径和二次常数干涉测量是对二次曲面离轴子孔径在弧矢、子午和中间焦点位置直接干涉测量,拟合得到初级像差系数,并结合化置差计算出顶点曲率半径和二次常数.详细介绍了该方法的基本原理,在此基础上将子孔径中心法线与光轴夹角分解为两个倾角分量α和β引入,改进了现有模型.提出在子孔径对称情况下,可通过调整、控制特定项的泽尼克系数值,消除β分量.进而对新的模型进行了简化,只考虑α分量的影响,给出了仅存在该分量时的非球面顶点半径和二次常数的计算公式,编写了仿真程序.在α=0.03 °,β=0时.直径100 mm,F数为3的抛物面反射镜离轴子孔径的初级像差系数的理论计算和数值仿真结果最大偏差仅为0.0002 λ.研究表明:在子孔径中心法线与光轴的调整存在一定误差时,在弧矢、子午和中间焦点处的初级像差系数特征关系仍然成立.     

空间点目标光谱探测与特征识别研究进展

光学观测是空间目标识别的重要手段,由于探测距离远,视场中的空间目标多呈现为非分辨的点目标。相比于传统的定轨测量和光度测量,光谱探测提供了波长维的可分辨信息,极大的提升了目标表面材质判别能力,并为目标状态反演提供了更可靠的依据,极具应用潜力。介绍了近年来国内外学者在空间点目标光谱探测及特征识别方面的典型研究进展,依据主要研究方法,分为多通道测光探测、高光谱探测、实验室光谱特性测量、目标特性建模仿真四个方向。其中,多通道测光获得了低光谱分辨率的测量数据,是常用的广域空间目标分类判别手段;高光谱探测研究反射能量在波长维的精细分布,有助于反演重点目标的材质组成;实验室光谱特性测量可在受控条件下模拟目标探测的物理过程,提供材质光谱特性数据库;目标特性建模仿真则对物理属性抽象特征化,研究目标光谱变化过程。通过分析国内外研究成果,总结当前研究的能力与不足,提出几点研究思路,为后续研究开展提供参考。     

第33届国际物理奥林匹克竞赛力热学与电化学综合实验试题解答及分析

介绍了第33届国际物理奥林匹克竞赛力热学与电化学综合实验试题及解答，分析了该实验题目的特点和实验过程。     

Numerical modeling of the motion of a torsion balance in the problem of measuring the Newtonian gravitational constant

The motion of a torsion balance with five degrees of freedom has been numerically simulated. It has been shown that the oscillations along the swing degrees of freedom are excited by the random noise of the seismic origin and their amplitude varies with time. It has been shown also that the nonlinear couplings between the swing and torsion degrees of freedom result in the appearance of combination oscillations. The methods for effectively suppressing these combination oscillations have been considered.     

Gravitational Perturbations on Local Experiments in a Satellite: The Dragging of Inertial Frame in the HYPER Project

We consider a nearly free falling Earth satellite where atomic wave interferometers are tied to a telescope pointing towards a faraway star. They measure the acceleration and the rotation relatively to the local inertial frame. We calculate the rotation of the telescope due to the aberrations and the deflection of the light in the gravitational field of the Earth. We show that the deflection due to the quadrupolar momentum of the gravity is not negligible if one wants to observe the Lense-Thirring effect of the Earth. We consider some perturbation to the ideal device and we discuss the orders of magnitude of the phase shifts due to the residual tidal gravitational field in the satellite and we exhibit the terms which must be taken into account to calculate and interpret the full signal. Within the framework of a geometric model, we calculate the various periodic components of the signal which must be analyzed to detect the Lense-Thirring effect. We discuss the results which support a reasonable optimism. As a conclusion we put forward the necessity of a more complete, realistic and powerful model in order to obtain a final conclusion on the theoretical feasibility of the experiment as far as the observation of the Lense-Thirring effect is involved.     

A New Relation Connecting Vibrationai Constant and Electronegativity in the Case of Diatomic Molecules

The electronegativity was defined by Pauling¹ as a measure of the power of an atom in the molecule to attract electrons to itself. This concept of electronegativity has undergone radical changes. Recent calculations of electronegativity show^2,3 that it is a complex quantity including an important atomic term depending on the charge and hybridization of the atom, and a molecular term depending on the length and the nature of the bonds in the molecule. In a molecular group of the type A-B, B is a halogen atom, say chlorine and A stands for different atoms of a subgroup of the periodic table. Since the nature of the bonds in the molecule AB and the electronegativity of halogen atom, B, is constant for a molecular group, the electronegativity, X, of atom A may be related to the dissociation energy and bond length which in its turn is related to the vibrational constant,ω_e, and the reduced mass, μ, of the molecule AB.