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We study cosmological solutions for the very early universe beginning at the Planck scale for a universe containing radiation, curvature and, as a simplification of a possible scalar field potential, a cosmological constant term. The…
WE analyse the universe inflation when the source of gravity is electromagnetic fields obeying nonlinear electrodynamics with two parameters and without singularities. The cosmology of the universe with stochastic magnetic fields is…
It is possible that the expansion of the universe began with an inflationary phase, in which the inflaton driving the process also was a Higgs field capable of stabilizing magnetic monopoles in a grand-unified gauge theory. If so, then the…
The standard model of cosmology is based on the hot Big Bang theory and the inflationary paradigm. Recent precise observations of the temperature and polarization anisotropies in the cosmic microwave background and the matter distribution…
Research over the past 25 years has led to the view that the rich tapestry of present-day cosmic structure arose during the first instants of creation, where weak ripples were imposed on the otherwise uniform and rapidly expanding…
Cosmological inflation generates primordial density perturbations on all scales, including those far too small to contribute to the cosmic microwave background. At these scales, isolated ultracompact minihalos of dark matter can form well…
We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin…
A mechanism for generating metric perturbations in inflationary models is considered. Long-wavelength inhomogeneities of light scalar fields in a decoupled sector may give rise to superhorizon fluctuations of couplings and masses in the…
In the past decade, the importance of dissipation and fluctuation to inflationary dynamics has been realized and has led to a new picture of inflation called warm inflation. Although these phenomena are common to condensed matter systems,…
We contrast the possibility of inflation starting a) from the universe's inception or b) from an earlier non-inflationary state. Neither case is ideal since a) assumes quantum mechanical reasoning is straightforwardly applicable to the…
One of the major pillars of modern cosmology theory is a period of accelerating expansion in the early universe. This accelerating expansion, or inflation, must be sustained for at least 30 e--foldings. One mechanism used to drive the…
Cosmic inflation provides a window to the highest energy densities accessible in nature, far beyond those achievable in any realistic terrestrial experiment. Theoretical insights into the inflationary era and its observational probes may…
There is controversy surrounding the origin and evolution of our universe's largest supermassive black holes (SMBHs). In this study, we consider the possibility that some of these black holes formed from the direct collapse of primordial…
Most high-energy constructions that realise a phase of cosmic inflation contain many degrees of freedom. Yet, cosmological observations are all consistent with single-field embeddings. We show how volume selection effects explain this…
A popular science article designed to introduce people familiar with basic cosmological nomenclature with models alternative to cosmological inflation. The paper briefly discusses the modern view of the Big Bang model, inflation (both its…
The early Universe inflation is well known as a promising theory to explain the origin of large scale structure of the Universe, a causal theory for the origin of primordial density fluctuations which may explain the observed density…
It has recently been speculated that the end state of a collapsing universe is a tachyonic big crunch. The time reversal of this process would be the emergence of an expanding universe from a tachyonic big bang. In this framework, we study…
Suppose that the early Universe starts with a quantum spacetime originated cosmological $\Lambda$-term at the Planck scale $M_{\rm pl}$. The cosmological energy density $\rho_{_{_\Lambda}}$ drives inflation and simultaneously reduces its…
The early Universe inflation is well known as a promising theory to explain the origin of large scale structure of Universe and to solve the early universe pressing problems. For a resonable inflation model, the potential during inflation…
The idea that a background of invisible material pervades the whole universe is as old as the history of natural philosophy. Modern particle physics and cosmology support that idea and identify in the cosmic vacuum the ultimate source of…