Related papers: Update on Electromagnetically Accelerating Univers…
A phenomenological model with an extreme accuracy is proposed for the cosmic time variation of the primordial fundamental constants (e, h, G and c) and the leptonic masses. The model is purely exploratory in that at the very early times the…
The cosmological constant, which was introduced by Einstein a century ago to allow for a static universe, experienced a revival two decades ago under the label dark energy as a parameter to model the observed accelerated expansion of the…
We discuss some cosmological consequences of a general model of coupled quintessence in which the phenomenological coupling between the cold dark matter and dark energy is a function of the cosmic scale factor $\epsilon(a)$. This class of…
We show that the combination of a fluid with a bulk dissipative pressure and quintessence matter can simultaneously drive an accelerated expansion phase and solve the coincidence problem of our current Universe. We then study some scenarios…
Cosmic acceleration may be the result of unknown physical processes involving either new fields in high energy physics or modifications of gravitation theory. In the latter case, such modifications are usually related to the existence of…
If the equation of state for "dark energy" varies periodically, the expansion of the Universe may have undergone alternating eras of acceleration and deceleration. We examine a specific form that survives existing observational tests, does…
A cosmological scenario where dark matter interacts with a variable vacuum energy for a spatially flat Friedmann-Robertson-Walker space-time is proposed and analysed to show that with a linear equation of state and a particular interaction…
The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of…
We explore the possibility of emergent cosmology using the effective potential formalism. We discover new models of emergent cosmology which satisfy the constraints posed by the cosmic microwave background (CMB). We demonstrate that, within…
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 expansion of the universe has been accepted by scientists for more than a century. However, since the 1990s, observations have suggested that the universe is expanding at an accelerating rate. Although the source of this acceleration is…
Theoretical approaches to explaining the observed acceleration of the universe are reviewed. We briefly discuss the evidence for cosmic acceleration, and the implications for standard General Relativity coupled to conventional sources of…
Recent observations suggest that the accelerated expansion of the Universe at late times is caused by a temporally changing dark energy component, rather than the constant one in the standard $\Lambda$CDM scenario. In this context…
Chapter1 introduces cosmic acceleration and outlines key features and limitations of GR and its alternatives, including teleparallel and symmetric teleparallel gravity. In Chapter2, we analyze the cosmological implications of…
The traditional "explanation" for the observed acceleration of the universe is the existence of a positive cosmological constant. However, this can hardly be a truly convincing explanation, as an expanding universe is not expected to have a…
The explanation of the accelerated expansion of the Universe poses one of the most fundamental questions in physics and cosmology today. If the acceleration is driven by some form of dark energy, one can try to constrain the parameters…
The present contribution deals with thermodynamic aspects of the model of Expansive Nondecelerative Universe. In this model, in the matter era a dependence T^CBR ~ E^CBR ~ a(exp -3/4) holds for the energy of cosmic background radiation,…
Recently found accelarated expansion of our Universe is due to the presence of a new kind of matter called "$\Lambda$ - field" or quintessence. The limitations on its equation of state are found from the fact of its unclustering at all…
An oscillating universe cycles through a series of expansions and contractions. We propose a model in which ``phantom'' energy with a supernegative pressure ($p < - \rho$) grows rapidly and dominates the late-time expanding phase. The…
A set of cosmological models that takes into account the variation of the particle number is presented. In this context both dark matter and dark energy can be explained using a single component, without assuming any exotic equation of…