Related papers: A New Cosmological Paradigm: the Cosmological Cons…
We are at a specific period of modern cosmology, during which the large increase of the amount of data leads to the idea that the determination of cosmological parameters has been achieved with a rather good precision. There is a large…
The lower limit on the age of the universe derived from globular cluster dating techniques, which previously strongly motivated a non-zero cosmological constant, has now been dramatically reduced, allowing consistency for a flat matter…
In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…
A diverse set of observations now compellingly suggest that Universe possesses a nonzero cosmological constant. In the context of quantum-field theory a cosmological constant corresponds to the energy density of the vacuum, and the wanted…
The evidence for the existence of dark matter in the universe is reviewed. A general picture emerges, where both baryonic and non-baryonic dark matter is needed to explain current observations. In particular, a wealth of observational…
The standard model of particle physics is marvelously successful. However, it is obviously not a complete or final theory. I shall argue here that the structure of the standard model gives some quite concrete, compelling hints regarding…
The case for a flat Cold Dark Matter model with a positive cosmological constant $\Lambda$ has been recently strongly advocated by some theoreticians. In this paper we give the observers point of view to the light of the most recent…
Recent observations of high-redshift supernovae seem to suggest that the global geometry of the Universe may be affected by a `cosmological constant', which acts to accelerate the expansion rate with time. But these data by themselves still…
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…
We discuss a model of the universe where dark energy is replaced by electrically-charged extremely-massive dark matter. The cosmological constant has a value of the same order as the mean matter density, consistent with observations, and is…
A cosmological model with total density close to critical (and flat geometry), dominated by dark matter and dark energy of unknown nature, and consistent with the basic predictions of the inflationary scenario is a very good fit to a…
The flat matter dominated Universe that dominated cosmological model building for much of the past 20 years does not correspond to the Universe in which we live. This has profound implications both for our understanding of dark matter, and…
The current expansion of the Universe has been observed to be accelerating, and the widely accepted spatially-flat concordance model of general relativistic cosmology attributes this phenomenon to a constant dark energy, a cosmological…
The Standard Model of cosmology of the 1980's was based on a remarkable interplay of ideas from particle theory, experiment and astrophysical observations. That model is now dead, and has been replaced by something far more bizarre.…
The concept of exotic charged dust is introduced here to represent dark matter. The term "exotic" means that the dust is not composed of normal matter, and the charge--for lack of a better term--is not an electric charge. It is also shown…
The principles of General Relativity allow for a non-vanishing cosmological constant, which can possibly be interpreted at least partially in terms of quantum-fluctuations of matter fields. Depending on sign and magnitude it can cause…
Nearly seventy per cent of the energy density in the universe is unclustered and exerts negative pressure. This conclusion -- now supported by numerous observations -- poses the greatest challenge for theoretical physics today. I discuss…
Quantum theory, general relativity, the standard model of particle physics, and the $\Lambda$CDM model of cosmology have all been spectacularly successful within their respective regimes of applicability, but many central problems remain…
We explore the effects of a positive cosmological constant on astrophysical and cosmological configurations described by a polytropic equation of state. We derive the conditions for equilibrium and stability of such configurations and…
The old cosmological constant problem is to understand why the vacuum energy is so small; the new problem is to understand why it is comparable to the present mass density. Several approaches to these problems are reviewed. Quintessence…