We investigate the possibility that dark energy does not couple to gravitation in the same way as ordinary matter, yielding a violation of the weak and strong equivalence principles on cosmological scales. We build a transient mechanism in which gravitation is pushed away from general relativity by a Born-Infeld gauge interaction acting as an abnormally weighting (dark) energy. This mechanism a...

the energy loss of a 3-dimensional harmonic oscillator due to the quadrupole radiation in quadratic f (r) gravity is calculated.

The Laser Interferometer Gravitational Wave Observatory (LIGO) is one of a new generation of detectors of gravitational radiation. The existence of gravitational radiation was first predicted by Einstein in 1916, however gravity waves have not yet been directly observed. One source of gravitation radiation is binary inspiral. Two compact bodies orbiting each other, such as a pair of black holes...

Gravity is one of the fundamental forces of Nature, and it is the dominant force in most astronomical systems. In common with all other phenomena, gravity must obey the principles of Special Relativity. In particular, gravitational forces must not be transmitted or communicated faster than light. This means that when the gravitational field of an object changes, the changes ripple outwards thro...

Gamma Ray Bursts (GRBs) are the most relativistic objects known so far, involving, on one hand an ultra-relativistic motion with a Lorentz factor Γ > 100 and on the other hand an accreting newborn black hole. The two main routes leading to this scenario: binary neutron star mergers and Collapsar the collapse of a rotating star to a black hole, are classical sources for gravitational radiation. ...

The existence of gravitational radiation is a direct prediction of Einstein’s theory of general relativity, published in 1916. The observation of gravitational radiation will open a new astronomical window on the universe, allowing the study of dynamic strong-field gravity, as well as many other astrophysical objects and processes impossible to observe with electromagnetic radiation. The relati...

There is a lot of current interest in sources of gravitational waves and active ongoing projects to detect such radiation, such as the LIGO project. These are long wavelength, low frequency gravitational waves. LISA would be sensitive to much longer wavelengths and lower fluxes. However compact stellar objects can generate high frequency (10 16 -10 21 Hz) thermal gravitational radiation, which ...