Related papers: Cosmology with a Decaying Vacuum Energy Parametriz…
Cosmological stasis is a new type of epoch in the cosmological timeline during which the cosmological abundances of different energy components -- such as vacuum energy, matter, and radiation -- remain constant despite the expansion of the…
We study cosmological perturbations in the context of an interacting dark energy model, in which the cosmological term decays linearly with the Hubble parameter, with concomitant matter production. A previous joint analysis of the…
In this talk we present a model of the universe in which dark energy is modelled explicitely with both a dynamical quintessence field and a cosmological constant. Our results confirm the possibility of a collapsing universe (for a given…
In this paper we study a new symmetry argument that results in a vacuum state with strictly vanishing vacuum energy. This argument exploits the well-known feature that de Sitter and Anti- de Sitter space are related by analytic…
We show that quantum decoherence, in the context of observational cosmology, can be connected to the cosmic dark energy. The decoherence signature could be characterized by the existence of quantum entanglement between cosmological eras. As…
In this work we study the evolution of matter-density perturbations for an arbitrary $\Lambda(t)$ model, and specialize our analysis to the particular phenomenological law $\Lambda = \Lambda_0 + 3\beta H^2$. We study the evolution of the…
The evolution of the wave function in quantum mechanics is deterministic like that of classical waves. Only when we bring in observers the fundamentally different quantum reality emerges. Similarly the introduction of observers changes the…
The main consequences of de Sitter Special Relativity to the Standard Cosmological Model of Physical Cosmology are examined. The cosmological constant Lambda appears, in this theory, as a manifestation of the proper conformal current, which…
In a recent article, Kleidis and Spyrou (2015) proposed that both dark matter (DM) and dark energy (DE) can be treated as a single component, if accommodated in the context of a polytropic DM fluid with thermodynamical content. Depending…
We look for cosmologies with a scalar field (dark energy without cosmological constant), which mimic the standard $\Lambda CDM$ cosmological model yielding exactly the same large-scale geometry described by the evolution of the Hubble…
Some remarkable examples of alternative cosmological theories are reviewed here, ranging from a compilation of variations on the Standard Model through the more distant quasi-steady-state cosmology, plasma cosmology, or universe models as a…
By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of…
Several attempts to solve the cosmological constant problem, which concerns the value of the cosmological constant being extremely smaller than the Standard Model mass scales, have introduced a scalar field with a very flat potential that…
It has been suggested previously that the observed cosmological constant Lambda corresponds to the remnant vacuum energy density of dynamical processes taking place at a cosmic age set by the mass scale M \sim E_{ew} of ultramassive…
The paper aims to provide an explanation for the tiny value of the cosmological constant and the low vacuum energy density to represent the dark energy. To accomplish this, we will search for a fundamental principle of symmetry in…
In a previous work it was shown that by considering the quantum nature of the gravitational field mediator, it is possible to introduce the momentum energy of the graviton into the Einstein equations as an effective cosmological constant.…
Dark energy is a fundamental constituent of our universe, its status in the cosmological field equation should be equivalent to that of gravity. Here we construct a dark energy and matter gravity coupling (DEMC) model of cosmology in a way…
Associated with the cosmic acceleration are the old and new cosmological constant problems, recently put into the more general context of the dark energy problem. In broad terms, the old problem is related to an unexpected order of…
It is pointed out that a collider experiment involves a local contribution to the energy-momentum tensor, a circumstance which not a common feature of the current state of the Universe at large characterized by the cosmological constant…
Quantization of a dust-like closed isotropic cosmological model with a cosmological constant is realized by the method of B. DeWitt \cite{1}. It is shown that such quantization leads to interesting results, in particular, to a finite…