Related papers: Rollercoaster Cosmology
The dynamics of hybrid models is usually approximated by the evolution of a scalar field slowly rolling along a nearly flat valley. Inflation ends with a waterfall phase, due to a tachyonic instability. This final phase is usually assumed…
The standard big bang cosmology has been greatly successful in explaining many observational aspects of the real universe. However, two particular diffficulties faced by it are the so-called ``horizon'' and ``flatness'' problems. By…
In this talk we discuss three different issues. First of all, there exist several proposals how to solve cosmological problems by adiabatic expansion of the Universe, without any use of inflation. We explain why these models do not solve…
In loop quantum cosmology (LQC) the big bang is replaced by a quantum bounce which is followed by a robust phase of super-inflation. Rather than growing unboundedly in the past, the Hubble parameter \emph{vanishes} at the bounce and attains…
An epoch of accelerated expansion, or inflation, in the early universe solves several cosmological problems. While there are many models of inflation only recently has it become possible to discriminate between some of the models using…
It has recently been realized that many theories of physics beyond the Standard Model give rise to cosmological histories exhibiting extended epochs of cosmological stasis. During such epochs, the abundances of different energy components…
Though predictions of the simplest inflationary cosmological models with cold dark matter, flat space and approximately flat initial spectrum of adiabatic perturbations are remarkably close to observational data, we have to go beyond them…
The early stages of the universe evolution are discussed according to the hot big bang model and the grand unified theories. The shortcomings of big bang are summarized and their resolution by inflationary cosmology is sketched.…
The eternal inflation problem continues to be considered one of standard's cosmology most serious shortcomings. This arises when one considers the effects of "quantum fluctuations" (QF) on the zero mode of inflaton field during a Hubble…
The Pre-Big Bang cosmology inspired generations of cosmologists in attempts to cure the initial Big Bang singularity using a fundamental length scale as proposed by String Theory. The existence of a phase of collapse/inflation with…
The big bang model and the history of the early universe according to the grand unified theories are introduced. The shortcomings of big bang are discussed together with their resolution by inflationary cosmology. Inflation, the subsequent…
This thesis is dedicated to studying cosmological inflation, which is a period of accelerated expansion in the very early Universe that is required to explain the observed anisotropies in the cosmic microwave background. Inflation, when…
The purpose of these lectures is to give a pedagogical introduction to inflation and the production of primordial perturbations, as well as a review of some of the latest developments in this domain. After a short introduction, we review…
Cosmological inflation and topological defects have been considered for a long time, either in disagreement or in competition. On the one hand an inflationary era is required to solve the shortcomings of the hot big bang model, while on the…
Many models of supersymmetry breaking involve particles with weak scale mass and Planck mass suppressed couplings. Coherent production of such particles in the early universe destroys the successful predictions of nucleosynthesis. We show…
One of the strongest arguments against the cosmological constant as an explanation of the current epoch of accelerated cosmic expansion is the existence of an earlier, dynamical acceleration, i.e. inflation. We examine the likelihood that…
In quantum cosmology the closed universe can spontaneously nucleate out of the state with no classical space and time. For the universe filled with a vacuum of constant energy density the semiclassical tunneling nucleation probability can…
Among the three cosmological enigma solved by the theory of inflation, {\it viz.} (a) large scale flatness, (b) absence of monopoles and strings, and (c) structure formation, the first two are addressed from the viewpoint of the observed…
We obtain cosmological constraints on models of inflation which exhibit rapid roll solutions. Rapid roll attractors exist for potentials with large mass terms and are thus of interest for inflationary model building within string theory. We…
We propose a novel explanation for the smallness of the observed cosmological constant (CC). Regions of space with a large CC are short lived and are dynamically driven to crunch soon after the end of inflation. Conversely, regions with a…