Related papers: Numerical coincidences and 'tuning' in cosmology
We study some cosmological constraints on the two phenomenological models of oscillating dark energy. In these scenarios, the equation of state of dark energy varies periodically and may provide a way to unify the early acceleration…
Recent results indicate the presence of a cosmological constant (or related dark energy) in the universe. It has been conjectured recently that the interaction parameters of physical theories may be dependant on the size parameter of the…
Any non-gravitational coupling between dark matter and dark energy modifies the cosmological dynamics. Interactions in the dark sector are considered to be relevant to address the coincidence problem. Moreover, in various models the…
The idea of possible time or space variations of the `fundamental' constants of nature, although not new, is only now beginning to be actively considered by large numbers of researchers in the particle physics, cosmology and astrophysics…
The standard model of cosmology is investigated using time dependent cosmological constant $\Lambda$ and Newton's gravitational constant $G$. The total energy content is described by the modified Chaplygin gas equation of state. It is found…
In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble…
The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…
We review a cosmology in which particles are fluctuationally created from a background Zero Point Field. This cosmology is consistent with recent observations of an ever expanding and accelerating universe, as also the recently confirmed…
Although quintessence cosmologies seem to explain the amount of cosmological constant today, the required conditions are severe. For example, an extremely slowly varying and light scalar field that rolls toward the vanishing vacuum energy…
We propose a cosmological model that makes a significant step toward solving the coincidence problem of the near similarity at the present of the dark energy and dark matter components. Our cosmology has the following properties: a) among…
Many particle physics models of matter admit solutions corresponding to stable or long-lived topological defects. In the context of standard cosmology it is then unavoidable that such defects will form during phase transitions in the very…
We are at an interesting juncture in cosmology. With new methods and technology, the accuracy in measurement of the Hubble constant has vastly improved, but a recent tension has arisen that is either signaling new physics or as-yet…
The energy densities of matter and the vacuum are currently observed to be of the same order of magnitude: $(\Omega_{m 0} \approx 0.3) \sim (\Omega_{\Lambda 0} \approx 0.7)$. The cosmological window of time during which this occurs is…
In this article the cosmological constant problems, as well as the astronomical evidence for a cosmologically significant homogeneous exotic energy density with negative pressure (quintessence), are reviewed for a broad audience of…
Models where Dark Matter and Dark Energy interact with each other have been proposed to solve the coincidence problem. We review the motivations underlying the need to introduce such interaction, its influence on the background dynamics and…
We derive the matching conditions for cosmological perturbations in a Friedmann Universe where the equation of state undergoes a sharp jump, for instance as a result of a phase transition. The physics of the transition which is needed to…
Dark energy models which alter the relative scaling behavior of dark energy and matter could provide a natural solution to the cosmic coincidence problem - why the densities of dark energy and dark matter are comparable today. A generalized…
We explore the possibility of having a composite (self-conserved) dark energy (DE) whose dynamics is controlled by the quantum running of the cosmological parameters. We find that within this scenario it is feasible to find an explanation…
Even when completely and consistently formulated, a fundamental theory of physics and cosmological boundary conditions may not give unambiguous and unique predictions for the universe we observe; indeed inflation, string/M theory, and…
Neutrinos play prominent roles in both particle physics and cosmology. In this talk, I will cover two broad topics. The first will be possible origins for neutrino masses and mixings and the implications of this physics for cosmology. Some…