Related papers: Cosmic structure, averaging and dark energy
From an observational perspective cosmology is today in excellent shape - advances in instrumentation and data processing have enabled us to study the universe in detail back to when the first galaxies formed, map the fluctuations in the…
Assuming the universe is spatially homogeneous on the largest scales lays the foundation for almost all cosmology. This idea is based on the Copernican principle, that we are not at a particularly special place in the universe.…
A discrete space-time structure lying at about the Planck scale may become manifest in the form of very small violations of the conservation of the matter energy-momentum tensor. In order to include such kind of violations, forbidden within…
Any theory invoked to explain cosmic acceleration predicts consistency relations between the expansion history, structure growth, and all related observables. Currently there exist high-quality measurements of the expansion history from…
The quantity and quality of cosmic structure observations have greatly accelerated in recent years. Further leaps forward will be facilitated by imminent projects, which will enable us to map the evolution of dark and baryonic matter…
Explanations of the late-time cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are mostly based on a dark energy field with fine-tuned, unnatural properties. There is a…
One possible explanation for the present observed acceleration of the Universe is the breakdown of homogeneity and isotropy due to the formation of non-linear structures. How inhomogeneities affect the averaged cosmological expansion rate…
Observational evidence indicating that the expansion of the universe is accelerating has surprised cosmologists in recent years. Cosmological models have sought to explain this acceleration by incorporating `dark energy', of which the…
A new phenomenological dark energy model, originally associated to the large-scale structure formation and considered as a solution to the fine-tuning and coincidence problems related to the cosmological constant, was analyzed within the…
The effective evolution of an inhomogeneous universe model in any theory of gravitation may be described in terms of spatially averaged variables. In Einstein's theory, restricting attention to scalar variables, this evolution can be…
Mounting observational data confirm that about 73% of the energy density consists of dark energy which is responsible for the current accelerated expansion of the Universe. We present observational evidences and dark energy projects. We…
The accelerating expansion of the universe is the most surprising cosmological discovery in many decades. In this short review, we briefly summarize theories for the origin of cosmic acceleration and the observational methods being used to…
General relativistic corrections to the expansion rate of the Universe arise when the Einstein equations are averaged over a spatial volume in a locally inhomogeneous cosmology. It has been suggested that they may contribute to the observed…
Dark energy has a dramatic effect on the dynamics of the universe, causing the recently discovered acceleration of the expansion. The dynamics are also central to the behavior of the growth of large scale structure, offering the possibility…
We review the current status of cosmological parameters, dark energy and large-scale structure, from a theoretical and observational perspective. We first present the basic cosmological parameters and discuss how they are measured with…
Astronomical observations suggest that today's Universe is dominated by a dark energy of unknown physical origin. One of the most notable consequences in many models is that dark energy should cause the expansion of the Universe to…
Here we consider a scenario in which dark energy is associated with the apparent area of a surface in the early universe. In order to resemble the cosmological constant at late times, this hypothetical reference scale should maintain an…
The linear cosmological perturbation theory of an almost homogeneous and isotropic perfect fluid universe is reconsidered and formally simplified by introducing new covariant and gauge-invariant variables with physical interpretations on…
The recent discovery of apparent cosmic acceleration has highlighted the depth of our ignorance of the fundamental properties of nature. It is commonly assumed that the explanation for acceleration must come from a new form of energy…
Holographic dark energy cosmology, also known as entropic cosmology, provides a concrete physical understanding of the late accelerated expansion of the universe. The acceleration appears to be a consequence of entropy associated with…