Related papers: Inhomogeneous vacuum energy
The recently observed accelerated expansion of the universe has put a challenge for its theoretical understanding. As a possible explanation of this, it is considered that the most part of the present universe is filled with a form of…
The general thermodynamic analysis of the quantum vacuum, which is based on our knowledge of the vacua in condensed-matter systems, is consistent with the Einstein earlier view on the cosmological constant. In the equilibrium Universes the…
Despite the many efforts, our theoretical understanding of the ultimate nature of the dark energy component of the universe still lags well behind the astounding experimental evidence achieved from the increasingly sophisticated…
We demonstrate that a transition from decelerated to accelerated cosmic expansion arises as a pure interaction phenomenon if pressureless dark matter is coupled to holographic dark energy whose infrared cutoff scale is set by the Hubble…
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…
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…
One of the most fundamental questions in cosmology is if dark energy is related just to a constant or it is something more complex. In this work, we call the attention to the fact that, under very general conditions, dark energy can be…
Scalar cosmological perturbations are investigated in the framework of a model with interacting dark energy and dark matter. In addition to these constituents, the inhomogeneous Universe is supposed to be filled with the standard…
We discuss the mechanism by which the field vacuum energy varies as a result of strong self-interaction. We propose a non-perturbative approach to treat strong interactions and discuss the problem in terms of quasi-particles describing the…
We investigate the interaction between dark energy and dark matter in the framework of irreversible thermodynamics of open systems with matter creation/annihilation. We consider dark energy and dark matter as an interacting two component…
An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary…
The behavior of the gravitating vacuum energy density in an expanding universe is discussed. A scenario is presented with a step-wise relaxation of the vacuum energy density. The vacuum energy density moves from plateau to plateau and…
In a recent paper (Phys. Rev. D95, 103504 (2017)) it is argued that, due to the fluctuations around its mean value, vacuum energy gravitates differently from what previously assumed. As a consequence, the universe would accelerate with a…
It is commonly stated that we have entered the era of precision cosmology in which a number of important observations have reached a degree of precision, and a level of agreement with theory, that is comparable with many Earth-based physics…
In this study, cosmological models are considered, where dark matter and dark energy are coupled and may exchange energy through non-gravitational interactions with one other. These interacting dark energy (IDE) models have previously been…
The lately proposed vacuum matter coupling model (arXiv:1303.6568) seems to be able to provide solutions to a variety of problems in cosmology. This coupling expressed by a transition term between vacuum energy and matter, but we point out…
We consider the dark energy model with barotropic equation of state, which interacts with dark matter through gravitation and another force, causing the energy-momentum exchange between them. Both components are described in approximation…
Recent observations from the Dark Energy Spectroscopic Instrument (DESI 2025) indicate a weakening of cosmic acceleration at low redshifts $z < 1$, with effective dark energy equation of state parameters $w_0 > -1$ and $w_a < 0$. We…
The discovery of accelerated cosmic expansion implies that, in addition to the attractive gravity of matter, there exists in our universe some other form of energy (dark energy or cosmological constant) producing a repulsive force. The…
Cosmologists are just beginning to probe the properties of the cosmic vacuum and its role in reversing the attractive pull of gravity to cause an acceleration in the expansion of the cosmos. The cause of this acceleration is given the…