玻色-爱因斯坦凝聚和重力测量——2001年诺贝尔物理学奖评介   总被引：6，自引：0，他引：6  

张昌达 《地质科技情报》2001,20(4):107-110

介绍了2001年诺贝尔物理学奖获得者康奈尔，韦曼，克特勒的科学研究成果，实验玻色－爱因斯坦凝聚（BEC）及其在理论上的意义和应用前景，讨论了BEC在研制高精度重力仪方面的应用问题，为此回顾了重力测量现状，朱棣文等研制的原子干涉重力仪和ClauserJ提出的物质波干涉重力仪，分析表明，如果利用BEC，则重力仪的测量精度在朱棣文等工作基础上将会有很大的提高。  相似文献   

Natural entropy production in an inflationary model for a polarized vacuum     

Marcelo Samuel Berman  Murari M. Som 《Astrophysics and Space Science》2007,310(3-4):277-279

Though entropy production is forbidden in standard FRW Cosmology, Berman and Som presented a simple inflationary model where entropy production by bulk viscosity, during standard inflation without ad hoc pressure terms can be accommodated with Robertson–Walker’s metric, so the requirement that the early Universe be anisotropic is not essential in order to have entropy growth during inflationary phase, as we show. Entropy also grows due to shear viscosity, for the anisotropic case. The intrinsically inflationary metric that we propose can be thought of as defining a polarized vacuum, and leads directly to the desired effects without the need of introducing extra pressure terms.  相似文献   

Further results for astrophysics from the cosmology within the framework of the Projective Unified Field Theory     

E. Schmutzer 《Astronomische Nachrichten》2000,321(3):137-155

Recently the 5‐dimensional Projective Unified Field Theory (PUFT) of the author (Schmutzer 1995a, Schmutzer 1995b) has been applied to a closed homogeneous isotropic cosmological model with the result of a cosmology without big bang (Schmutzer 1999a, Schmutzer 1999b). Continuing this approach, in this paper following subjects are treated: recalculation of numerical values of cosmological quantities, exact solution of the field equations to a point‐like body, motion of a test body in such a field, definition of the empirical effective gravitational factor (“constant”), Einstein effects compared to the empirical situation, adiabatic approximation of the motion of an orbiting testbody under the influence of the expanding cosmos (transition of the ellipses to circles, decrease of the radius of the orbiting bodies, decrease of the excentricity, increase of the frequency of orbiting objects etc.), heat production in a moving body induced by the cosmological expansion with application to various cosmic objects.  相似文献   

New mass formula for spherically symmetric stellar configurations     

U. Bleyer  L. Sh. Grigorian  R. M. Avakian  E. V. Chubarian 《Astronomische Nachrichten》1995,316(1):1-7

A new formula is derived for the mass of spherically symmetric stellar configurations. An expression will be given where the mass square is connected to an integral over the pressure of gravitating matter. This formula turns out to hold for Newtonian gravity, for Einstein's GRT, for projective and bimetric scalar-tensor and further theories of gravitation.  相似文献   

Tunneling analysis under the influences of Einstein–Gauss–Bonnet black holes gravity theory     

《New Astronomy》2022

We consider an equation of motion for Glashow–Weinberg–Salam model and apply the semiclassical Hamilton–Jacobi process and WKB approximation in order to compute the tunneling probability of W-bosons in the background of electromagnetic field to analyze the quantum gravity effects of charged black hole(BH) in Einstein–Gauss–Bonnet gravity theory. After this, we examine the quantum gravity influences on the generalized Lagrangian field equation. We make clear that quantum gravity effects leave the remnants on the tunneling radiation becomes non-thermal. Moreover, we analyze the graphical behavior of quantum gravity influences on corrected Hawking temperature for spin-1 particles for charged BHs.  相似文献   

正确认识“爱因斯坦”火车问题     

蒲明刚  潘必凯 《成都信息工程学院学报》1990,(1)

本文对一些书本在解释“爱因斯坦火车”例中存在的矛盾作了概述、并以“空间收缩效应”这一狭义相对论的实验基础为依据,提出正确解释。同时介绍由类时间隔事件的性质间接解释“爱氏火车”一例的方法。  相似文献   

Einstein A-coefficients for rotational transitions in cyclopropenylidene     

A. K. Sharma  Suresh Chandra 《Journal of Astrophysics and Astronomy》1996,17(1-2):41-52

Einstein A-values are given for the electric dipole transitions in the C₃ H₂-molecule between the rotational levels of the vibrational ground state up to 85cm^-1. The mean radiation life-times of the levels are calculated from the Einstein A-values. These values can be used as input parameters for analysing the spectra of C₃H₂  相似文献   

The ratio of measured to total sediment discharge     

Chun-Yao Yang  Pierre Y. Julien 《国际泥沙研究》2019,34(3):262-269

It is important to examine the ratio of measured to total sediment discharge to determine the error in measured sediment transport rates from depth-integrated samplers. The ratio of measured to total sediment discharge as well as the ratio of suspended to total sediment discharge are examined based on the Modified Einstein Procedure. Both ratios reduce to a function of the ratio of shear velocity, $u_{*}$, to the fall velocity, $\omega$, of suspended material, $u_{*}/\omega$, and the ratio, $h/d_s$, of flow depth, h, to the median grain size of bed material, $d_{50}$. In rivers transporting fine material (such as silt or clay), the ratio of suspended to total load is a function of the ratio, $h/d_{50}$. In this study, it is found that the ratio of measured to total load becomes a simple function of flow depth. For fine sediment transport, with a Rouse number (Ro) $<0.3$, at least 80% of sediment load is in suspension when $h/d_{50}>15$, and at least 90% of sediment load is measured from depth integrating samples when $h>1\mathrm{m}$. Detailed measurements from 35 river stations in South Korea demonstrate that sand sizes and finer fractions predominantly are transported in suspension. Also, at least 90% of sand and finer fractions are transported in suspension in gravel and sand bed rivers when the discharge is larger than the mean annual discharge.  相似文献   

Stellar models with generalized polytropic equation of state     

《New Astronomy》2022

We find new classes of exact solutions to the Einstein field equations where the matter distribution satisfies a generalized polytropic equation of state. The matter distribution is uncharged with anisotropic pressures. Equations of state for polytropes and quark matter are contained as special cases. The matter variables and metric potentials can be obtained explicitly. Known solutions, for the choice of the gravitational potential made in this analysis, arise as special cases for particular choice of the equation of state parameters. A detailed physical analysis indicates that the model is well behaved.  相似文献   

The Pioneer anomaly and a Machian universe     

Marcelo Samuel Berman 《Astrophysics and Space Science》2007,312(3-4):275-278

We discuss astronomical and astrophysical evidence, which we relate to the principle of zero-total energy of the Universe, that imply several relations among the mass M, the radius R and the angular momentum L of a “large” sphere representing a Machian Universe. By calculating the angular speed, we find a peculiar centripetal acceleration for the Universe. This is an ubiquituous property that relates one observer to any observable. It turns out that this is exactly the anomalous acceleration observed on the Pioneers spaceships. We have thus shown that this anomaly is to be considered a property of the Machian Universe. We discuss several possible arguments against our proposal.  相似文献