Einstein’s General Relativity predicts that pressure, in general stresses, play a similar role to energy density, ǫ = ρc (with ρ being corresponding mass density), in generating gravity. The source of gravitational field, the active gravitational mass density, sometimes referred to as Whittaker’s mass density, is ρgrav = ρ + 3p/c , where p is pressure in the case of an ideal fluid. Whittaker’s ...

The relative velocity between objects with finite affects the reaction them. This effect is known as general Doppler effect. Laser Interferometer Gravitational-Wave Observatory (LIGO) discovered gravitational waves and found their speed to be equal of light c . Gravitational are generated following a disturbance in field; they affect force on an object. Just subject effect, so waves. article ex...

It is accepted that quasars are powered by supermassive black holes (SMBH) with masses in the range 10 − 10M in their cores. Occasionally, compact stars can plunge into SMBH. In addition, there may be a number of such compact objects circling the central SMBH in any given quasar. Both of these processes are known to emit gravitational waves. LISA has the right sensitivity to detect these waves....

Now that gravitational waves have been observed, the race is on to design better and more sensitive gravitational telescopes. The LIGO telescope measures gravitational waves by precisely measuring the distance between reflectors. As gravitational waves pass through LIGO the distance changes very slightly. One way to improve over LIGO is to create a more sensitive telescope in space following si...

The propagation of a gravitational wave (GW) through a magnetized plasma is considered. In particular, we study the excitation of fast magnetosonic waves (MSW) by a gravitational wave, using the linearized general-relativistic hydromagnetic equations. We derive the dispersion relation for the plasma, treating the gravitational wave as a perturbation in a Minkowski background space-time. We show...

Gravitational waves act like lenses for the light propagating through them. This phenomenon is described using the vector formalism employed for ordinary gravitational lenses, which was proved to be applicable also to a non{stationary spacetime, with the appropriate modi cations. In order to have multiple imaging an approximate condition analogous to that for ordinary gravitational lenses must ...

We analyze the effect of weak field gravitational waves on the timing of pulsars, with particular attention to gauge invariance, that is, to the effects that are independent of the choice of coordinates. We find: (i) the Doppler shift cannot be separated into gauge invariant gravitational wave and kinetic contributions; (ii) a gauge invariant separation can be made for the time derivative of th...

This article deals with the first detection of gravitational waves by the advanced Laser Interferometer Gravitational Wave Observatory (LIGO) detectors on 14 September 2015, where the signal was generated by two stellar mass black holes with masses 36 M and 29 M that merged to form a 62 M black hole, releasing 3 M energy in gravitational waves, almost 1.3 billion years ago. We begin by providin...