Related papers: Dark energy and cosmic acceleration
We suggest an interpretation of Einstein Equations of General Relativity at large scales in which the Cosmological constant is exactly zero in the limit of zero spacetime variations of fundamental constants. We argue that in a…
By using an unmodified Einstein gravity theory it is shown that all of the speeding-up effects taking place in the current universe are entirely due to the quantum effects associated with the background radiation or to the combination of…
In this article, we review a series of recent theoretical results regarding a conventional approach to the dark energy (DE) concept. This approach is distinguished among others for its simplicity and its physical relevance. By compromising…
A probable solution of the cosmological constant problem was recently found. We propose that dark energy of the Universe is vacuum energy. Our Universe during its expansion is spending its vacuum energy for creation of new quantum states,…
It was first observed at the end of the last century that the universe is presently accelerating. Ever since, there have been several attempts to explain this observation theoretically. There are two possible approaches. The more…
The discovery of the present accelerated expansion of space changed everything regarding cosmology and life's ultimate prospects. Both the optimistic scenarios of an ever (but decelerated) expanding universe and of a collapsing universe…
The discovery of cosmic acceleration is one of the most important developments in modern cosmology. The observation, thirteen years ago, that type Ia supernovae appear dimmer that they would have been in a decelerating universe followed by…
We investigate the possibility of a dark energy component that is scaling with epochs. A phenomenological model is introduced whose energy density depends on the redshift in such a way that a smooth transition among the three dominant…
It may be difficult to single out the best model of dark energy on the basis of the existing and planned cosmological observations, because many different models can lead to similar observational consequences. However, each particular model…
The cosmological standard model at present is widely accepted as containing mainly things we do not understand. In particular the appearance of a Cosmological Constant, or dark energy, is puzzling. This was first inferred from the Hubble…
One of the main goals of physical cosmology is to reconstruct the expansion history of the universe and finding the actual model of dark energy. In this article I review the difficulties of understanding dark energy and discuss about two…
In the late 1990s, observations of type Ia supernovae led to the astounding discovery that the universe is expanding at an accelerating rate. The explanation of this anomalous acceleration has been one of the great problems in physics since…
A precise determination, and comparison, of the epoch of the onset of cosmic acceleration, at redshift z_acc, and of dark energy domination, at z_eq, provides an interesting measure with which to parameterize dark energy models. By…
The origin of the observed acceleration of the expansion of the universe is a major problem of modern cosmology and theoretical physics. Simple estimations of the contribution of vacuum to the density energy of the universe in quantum field…
In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…
Recent observations of Type Ia supernovae provide evidence for the acceleration of our universe, which leads to the possibility that the universe is entering an inflationary epoch. We simulate it under a ``big bounce'' model, which contains…
We introduce a new proposal for the onset of cosmic acceleration based on mass-varying neutrinos. When massive neutrinos become nonrelativistic, the $Z_2$ symmetry breaks, and the quintessence potential becomes positive from its initially…
The presently accelerating universe may keep accelerating forever, eventually run into the event horizon problem, and thus be in conflict with the superstring idea. In the other way around, the current accelerating phase as well as the fate…
Recent observations confirm that our universe is flat and consists of a dark energy component $\Omega_{DE}\simeq 0.7$. This dark energy is responsible for the cosmic acceleration as well as determines the feature of future evolution of the…
I consider some of the issues we face in trying to understand dark energy. Huge fluctuations in the unknown dark energy equation of state can be hidden in distance data, so I argue that model-independent tests which signal if the…