Related papers: Dark energy from gravitational collapse?

Einstein gravitation is known to give rise to the formation of singularities at high densities unless the dominant energy condition is made invalid by the occurrence of new physics: we show that such a new physics can be the already present…

We study the homogeneous gravitational collapse of a spherical cloud of matter in a super-renormalizable and asymptotically free theory of gravity. We find a picture that differs substantially from the classical scenario. The central…

Cosmic acceleration is explained quantitatively, as an apparent effect due to gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe. "Dark energy" is a misidentification of…

We review the current status of cosmological parameters, dark energy and large-scale structure, from a theoretical and observational perspective. We first present the basic cosmological parameters and discuss how they are measured with…

Collapsed objects have definitely been observed: some are stellar-mass objects, the endpoint of massive stars; others, millions of times more massive, have been discovered in the cores of most galaxies. Their formation poses some…

The gravitational collapse and the birth of a new universe are considered in terms of quantum mechanics. Transitions from annihilation of matter to deflation in the collapse and from inflation to creation of matter in the birth of a…

In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body…

We suggest that the eventual gravitational repulsion between matter and antimatter may be a key for understanding of the nature of dark matter and dark energy. If there is gravitational repulsion, virtual particle-antiparticle pairs in the…

Dark energy appears to be the dominant component of the physical Universe, yet there is no persuasive theoretical explanation for its existence or magnitude. The acceleration of the Universe is, along with dark matter, the observed…

We explore the fate of the universe given the possibility that the density associated with `dark energy' may decay slowly with time. Decaying dark energy is modeled by a homogeneous scalar field which couples minimally to gravity and whose…

A simple model of a universe is presented composed of black holes and black branes. It uses the most simplest approximations and models of General Relativity and Quantum Dynamics to offer an idea of an unification and gives a possible…

We use a new, exact approach in calculating the energy density measured by an observer living on a brane embedded in a charged black hole spacetime. We find that the bulk Weyl tensor gives rise to non-linear terms in the energy density and…

It has been observed recently that many properties of some near extremal black holes can be described in terms of bound states of D-branes. Using a non-renormalization theorem we argue that the D-brane description is the correct quantum…

To test recent ideas about lower dimensional gravity bound to a brane, we construct exact solutions describing black holes on two-branes in four dimensions. We find that 2+1 gravity is indeed recovered at large distances along the brane,…

Cosmological observations allow the possibility that dark energy is caused by phantom fields. These fields typically lead to the occurrence of singularities in the late Universe. We review here the status of phantom singularities and their…

The new, rapidly developing field of theoretical research --- studies of dark energy interacting with black holes (and, in particular, accreting onto black holes) --- is reviewed. The term `dark energy' is meant to cover a wide range of…

We show that an S-Brane which arises in the inside of the black hole horizon when the Weyl curvature reaches the string scale induces a continuous transition between the inside of the black hole and the beginning of a new universe. This…

It is shown that space curvature can be disposed of by properly taking into account gravitational self energies. This leads to a parameter free modification of Newton's law, violating Gauss theorem, which accounts for the crucial tests of…

The usual brane world scenario with anti de Sitter bulk has been generalized by considering a general form of energy momentum tensor in the bulk. The modified Einstein equation on the brane has been constructed. Two examples have been cited…

Primordial black hole formation has been discussed widely, when density perturbations in the early universe cause matter to collapse gravitationally, giving rise to these ultra-compact objects. We propose and point out that such a…