Related papers: A new look at dark energy
Astronomical observations have shown that the expansion of the universe is at present accelerating, consistently with a constant negative pressure or tension. This is a major puzzle because we do not understand why this tension is so small…
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…
For physicists, recent developments in astrophysics and cosmology present exciting challenges. We are conducting "experiments" in energy regimes some of which will be probed by accelerators in the near future, and others which are…
A hypothesis is presented for explanation of the dark matter and dark energy properties in terms of a new interaction field with spin 3.
The origin of dark matter in the universe may be weakly interacting scalar particles produced by amplification of quantum fluctuations during a period of dilaton-driven inflation. We present two interesting cases, the case of small…
Early dark energy, as a proposed solution to the Hubble tension, faces an additional "why now" problem. Why should dark energy emerge just prior to recombination, billions of years before the onset of cosmic acceleration? Assisted…
Over the past three years we have determined the basic features of the Universe -- spatially flat; accelerating; comprised of 1/3 a new form of matter, 2/3 a new form of energy, with some ordinary matter and a dash of massive neutrinos; and…
Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing…
In this letter we show that, at its fundamental level, phantom dark energy is a fluid made up of time crystals that permeate the fabric of space-time. In turn, any well-behaved stable theory of a non-canonical scalar field that acts as…
In order to understand the nature of the accelerating expansion of the late-time universe, it is important to experimentally determine whether dark energy is a cosmological constant or dynamical in nature. If dark energy already exists…
The problem of dark energy can be roughly stated as the proposition and validation of a cosmological model that can explain the phenomenon of the accelerated expansion of the Universe. This problem is an open discussion topic in modern…
We propose that the totality of dark matter in the universe might ascribe its origin to one of the key properties of cosmological inflation, that it may be eternal: regions that at the end of the primordial accelerated expansion of the…
The origin of cosmic rays with energies higher than 10$^{20}$ eV remains a mystery. Accelerating particles up to these energies is a challenge even for the most energetic astrophysical objects known. While the isotropy in arrival directions…
A fundamental question that can be answered in the next decade is: WHAT IS THE ORIGIN OF THE HIGHEST ENERGY COSMIC PARTICLES? The discovery of the sources of the highest energy cosmic rays will reveal the workings of the most energetic…
Dark matter is a fundamental constituent of the universe, which is needed to explain a wide variety of astrophysical and cosmological observations. Although the existence of dark matter was first postulated nearly a century ago and its…
The acceleration of the universe is described as a dynamical effect of the extrinsic curvature of space-time. By extending previous results, the extrinsic curvature is regarded as an independent spin-2 field, determined by a set of…
The origin of the galaxies represents an important focus of current cosmological research, both observational and theoretical. Its resolution involves a comprehensive understanding of star formation, galaxy dynamics, the cosmology of the…
In this work we review some of the theoretical efforts and experimental evidences related to Dark matter and Dark energy problems in the universe. These dilemmas show us how incomplete our knowledge of gravity is, and how our concepts about…
About 80 percent of the matter content of the universe is dark matter. However, the particle origin of dark matter is yet to be established. Many extensions of the Standard Model (SM) contain candidates of dark matter. The search for the…
The universe should be dark at energies exceeding $\sim 5\times 10^{19}$ eV. This simple but solid prediction of our best known particle physics is not confirmed by observations, that seem to suggest a quite different picture. Numerous…