A tool for the interactive study of gravitational lensing is presented. Gravitational lensing is a known astrophysical phenomenon explained by means of the General Relativity Theory and it is nowadays the only scale independent method for measuring the mean matter density in the Universe. The gravitational lensing problem along with the associated physics is briefly described. The algorithm use...

We measured Newton's gravitational constant G using a new torsion balance method. Our technique greatly reduces several sources of uncertainty compared to previous measurements: (1) It is insensitive to anelastic torsion fiber properties; (2) a flat plate pendulum minimizes the sensitivity due to the pendulum density distribution; (3) continuous attractor rotation reduces background noise. We o...

Progress and plans are reported for a program of gravitational physics experiments using cryogenic torsion pendula undergoing large amplitude torsional oscillation. The program includes a UC Irvine project to measure the gravitational constant G and joint UC Irvine– U. Washington projects to test the gravitational inverse square law at a range of about 10 cm and to test the weak equivalence pri...

Multidimensional cosmological models with factorizable geometry and their dimensional reduction to effective four-dimensional theories are analyzed on sensitivity to different scalings. It is shown that a noncorrect gauging of the effective four-dimensional gravitational constant within the dimensional reduction results in a non-correct rescaling of the cosmological constant and the gravexciton...

The direct detection of gravitational waves is a major goal of current astrophysics. We provide details of a new method for detecting a stochastic background of gravitational waves using pulsar timing data. Our results show that regular timing observations of 40 pulsars each with a timing accuracy of 100 ns will be able to make a direct detection of the predicted stochastic background from coal...

The prospects for the observation of electromagnetic emissions by gravitational wave sources first detected using a network of interferometers are discussed. Various emission mechanisms and detection techniques for compact binary inspirals are studied to show that the pointing ability of gravitational wave observatories and the efficacy of electromagnetic detectors can be combined to predict th...

Evidence is presented which indicates that almost all HCGs are dynamically associated with generally elongated loose groups of galaxies, and are compact cores of the latter. Most of those loose groups, the direction of elongation of which lies at angles close to 45◦ with the line of sight, were revealed by previous investigations. Hence, HCGs have, probably, longer life-times than it has been d...