Conveners
Inflation: perturbations, initial singularities and emergent universes: Monday block 1
- Stefano Ansoldi (University of Udine)
- Eduardo Guendelman (Ben Gurion University)
Inflation: perturbations, initial singularities and emergent universes: Monday block 2
- Stefano Ansoldi (University of Udine)
- Eduardo Guendelman (Ben Gurion University)
Inflation: perturbations, initial singularities and emergent universes: Tuesday block 1
- Eduardo Guendelman (Ben Gurion University)
- Stefano Ansoldi (University of Udine)
Inflation: perturbations, initial singularities and emergent universes: Tuesday block 2
- Eduardo Guendelman (Ben Gurion University)
- Stefano Ansoldi (University of Udine)
Description
In this parallel session, we will have talks that consider inflationary models of all kinds and their relation to observables, reheating, production of primordial black holes, string theory ideas concerning perturbations and quintessential inflation. We will review also issues concerning the existence of initial singularities in the context of inflationary universes. Interesting theorems have been shown by Borde, Guth and Vilenkin indicating the existence of an initial singularity for the inflationary scenarios. The Emergent Universe, first proposed by George F. R. Ellis and Roy Maartens appeared then as an important exception to such theorem. This simple version of the Emergent Universe is unstable, but more developed versions seem stable, both classically and quantum mechanically. A consistent Emergent Universe could be more constrained and therefore more predictive, even on issues like the cosmological constant and others.
We demonstrate that the Raychaudhuri equation remains unchanged for certain solutions of scalar fields $\phi$ that have a non-canonical Lagrangian of the form $\mathcal{L}(X,\phi)=-V(\phi)F(X)$, with $X=\frac{1}{2} g_{\mu\nu} \nabla^{\mu}\phi \nabla^{\nu} \phi$ and $V(\phi)$ represents the potential. There are several solutions available for both homogeneous and inhomogeneous fields, which are...
Novel proposal is made for candidate Fuzzy dark matter.Interestingly it has connections to primordial black holes which can seed supermassive black hole and play critical role in galaxy formation.
I will discuss eternal inflation and the key role that inflation plays in resolving cosmological singularities. I will describe how proposed no-go theorems, such as the famous theorem of Borde, Guth and Vilenkin (BGV) are circumvented or obviated. Our exploration encompasses eternal inflating, loitering, and bouncing models, shedding light on the critical aspects that underpin geodesic...
Shibata and Sasaki [Phys. Rev. D 60, 084002 (1999)] introduced the so-called compaction function. Since then, it has been empirically established that the maximum value of this function (or its volume-averaged counterpart) in the long-wavelength solutions gives a very robust threshold of primordial black hole formation. In this paper, we show that in spite of initial intention, the...
We construct a (quantum mechanically) modified model for the Oppenheimer-Snyder collapse scenario where the exterior of the collapsing dust ball is a Hayward black hole spacetime and the interior is a dust Friedmann-Robertson-Walker cosmology. This interior cosmology is entirely determined by the junction conditions with the exterior black hole. It turns out to be non-singular, displaying a...
We show by matching two flat spaces one in Minkowski coordinates ( empty space) and the other in Minkowski coordinates after a special conformal transformation (also empty space) through a bubble with positive and constant surface tension, that the motion of the bubble is hyperbolic. If the surface tension is very big the initial size of the bubble is as small as we wish, so that we can indeed...
Cosmological inflation is a popular paradigm for understanding Cosmic Microwave Background Radiation (CMBR); however, it faces many conceptual challenges. An alternative mechanism to inflation for generating an almost scale-invariant spectrum of perturbations is a bouncing cosmology with an initial matter-dominated contraction phase, during which the modes corresponding to currently observed...
A two scalar field model that incorporates non Riemannian Measures of integration or usually called Two Measures Theory (TMT) is introduced, in order to unify the early and present universe. In the Einstein frame a K-essence is generated and, as a consequence for the early universe, we can have Inflation and then subsequent early and present present dark epochs with consistent generation...
There is solid theoretical and observational motivation behind the idea of scale invariance as a fundamental symmetry of Nature. We consider a recently proposed classically scale-invariant inflationary model, quadratic in curvature and featuring a scalar field nonminimally coupled to gravity. We go beyond earlier analytical studies, which showed that the model predicts inflationary observables...
We revisit basic problems of classical Friedmann-Lemaître cosmology that motivate the idea of cosmological inflation in light of modern ideas on quantum geometry. Classical cosmology assumes the validity of General Relativity with its smooth Riemannian spacetime geometry at all scales, even below the Planck scale where quantum-gravitational effects are expected to dominate. We argue that...
In this work, we examine the dynamical aspects of the cosmological Mixmaster model within the framework of a non-commutative Generalized Uncertainty principle (GUP) theory.
The theory is formulated classically by introducing a well-defined symplectic form that differs from the ordinary one, thereby inducing a deformation of the Poisson brackets.
We first investigate the behavior of the ...
Recent remarkable discoveries, such as Einstein’s gravitational waves, “impossible early” galaxies and quasars, 2D photon Bose-Einstein condensate with rest energy etc. provide a solid experimental and observational basis for “fiery marriage of general relativity with quantum theory” (J.Wheeler).
Consecutively, in a physical logic, nature inspire us that primordial black holes (PBHs)...
Big Bang Nucleosynthesis provides us with an observational insight into the very early Universe. Since this mechanism of light element synthesis comes out of the standard model of particle cosmology which follows directly from General Relativity, it is expected that any modifications to GR will result in deviations in the predicted observable parameters which are mainly, the neutron-to-proton...
