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We present an elementary introduction to the Early Universe. The basic features of the hot Big Bang are reviewed in the framework of the fundamental physics involved. Shortcomings of the standard scenario and open problems are discussed as well as the key ideas for their resolution.
This is a review on cosmological perturbation theory. After an introduction, it presents the problem of gauge transformation. Gauge invariant variables are introduced and the Einstein and conservation equations are written in terms of these variables. Some examples, especially perfect fluids and scalar fields are presented in detail. The generation of perturbations during inflation is studied...
The linear anisotropies in the temperature of the cosmic microwave background (CMB) radiation and its polarization provide a clean picture of fluctuations in the universe some 370 kyr after the big bang. Simple physics connects these fluctuations with those present in the ultra-high-energy universe, and this makes the CMB anisotropies a powerful tool for constraining the fundamental physics...
I discuss the classical cosmological tests, i.e., angular size-redshift, flux-redshift, and galaxy number counts, in the light of the cosmology prescribed by the interpretation of the CMB anisotropies. The discussion is somewhat of a primer for physicists, with emphasis upon the possible systematic uncertainties in the observations and their interpretation. Given the curious composition of...
I briefly review our current understanding of dark matter and dark energy. The first part of this review focusses on issues pertaining to dark matter including observational evidence for its existence, current constraints and the ‘abundance of substructure’ and ‘cuspy core’ issues which arise in CDM. I also briefly describe MOND. The second part of this review focusses on dark energy. In...
This review provides a non-technical introduction into time dependent phenomena in string theory and their possible applications to cosmology, mainly within the context of string low energy effective theories. Particular emphasis is placed on the relation between string theory and inflation. We also discuss certain topology changing processes in string theory in the context of cosmology.
According to recent ideas from particle physics, the universe could be a higher-dimensional spacetime, with our observable part of the universe being a four-dimensional “brane” surface. In this picture, Standard Model particles and fields are confined to the brane while gravity propagates freely in all dimensions. If one of the extra spatial dimensions is very large relative to the Planck...
As several large scale interferometers are beginning to take data at sensitivities where astrophysical sources are predicted, the direct detection of gravitational waves may well be imminent. This would (finally) open the long anticipated gravitational-wave window to our Universe, and should lead to a much improved understanding of the most violent processes imaginable; the formation of black...
Over the last decade, advances in computer hardware and numerical algorithms have opened the door to the possibility that simulations of sources of gravitational radiation can produce valuable information of direct relevance to gravitational wave astronomy. One source in particular is believed to be of extreme importance: the inspiral and merger of a binary black hole system. Simulations...
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