Related papers: Eternal Inflation: Prohibited by Quantum Gravity?
In recent literature on eternal inflation, a number of measures have been introduced which attempt to assign probabilities to different pocket universes by counting the number of each type of pocket according to a specific procedure. We…
A theory of exponential modified gravity which explains both early-time inflation and late-time acceleration, in a unified way, is proposed. The theory successfully passes the local tests and fulfills the cosmological bounds and,…
We propose a method to extract predictions from quantum cosmology for inflation that can be confronted with observations. Employing the tunneling boundary condition in quantum geometrodynamics, we derive a probability distribution for the…
We discuss the generic phenomenology of quantum gravity and, in particular, argue that the observable effects of quantum gravity, associated with new, extended, non-local, non-particle-like quanta, and accompanied by a dynamical…
In this short note we consider the decoherence of the minisuperspace background degrees of freedom due to the long wavelength scalar and tensor perturbations becoming unobservable within the Born-Oppenheimer approach to the quantum gravity.…
An alternative scenario about the phenomenology of primordial Universe is k-inflation. According to this concept, inflation can be achieved by nonstandard kinetic term of scalar field, namely the inflaton. In this project we focus on…
As part of our program to develop a general theory of relativity for open systems, we introduce a covariant theory that incorporates the effects of classical and quantum spacetime alterations in a new metric tensor that effectively includes…
Quantum gravity effects are traditionally tied to short distances and high energies. In this essay we argue that, perhaps surprisingly, quantum gravity may have important consequences for the phenomenology of the infrared. We center our…
Eternally inflating universes can contain thermalized regions with different values of the cosmological parameters. In particular, the spectra of density fluctuations should be different, because of the different realizations of quantum…
In this review, we discuss inflation models based on supergravity. After explaining the difficulties in realizing inflation in the context of supergravity, we show how to evade such difficulties. Depending on types of inflation, we give…
Eternal inflation is studied in the context of warm inflation. We focus on different tools to analyze the effects of dissipation and the presence of a thermal radiation bath on the fluctuation-dominated regime, for which the…
Inflation models can have an early phase of inflation where the evolution of the inflaton is driven by quantum fluctuations before entering the phase driven by the slope of the scalar field potential. For a Coleman-Weinberg potential this…
Using spectral regularisation, we compute the Weyl anomaly and express the anomaly generating functional of the quantum effective action through a collective scalar degree of freedom of all quantum vacuum fluctuations. Such a formulation…
In the hope of avoiding model dependence of the cosmological observables, phenomenological parametrizations of Cosmic Inflation have recently been proposed. Typically, they are expressed in terms of two parameters associated with an…
Cosmological inflation remains a key paradigm for explaining the earliest stages of the Universe, yet the theoretical limitations of General Relativity (GR) motivate the development of alternative formulations capable of addressing both…
The 2015 Planck data release tightened the region of the allowed inflationary models. Inflationary models with convex potentials have now been ruled out since they produce a large tensor to scalar ratio. Meanwhile the same data offers…
A continuous process of creation of particles is investigated as a possible connection between the inflationary stage with late cosmic acceleration. In this model, the inflationary era occurs due to a continuous and fast process of creation…
The expansion of spacetime alters the energy-time uncertainty principle, allowing virtual particles to persist longer than in flat space. For a given expansion the effect is largest for massless particles which are not conformally…
We hereby present a class of multidimensional higher derivative theories of gravity that realizes an ultraviolet completion of Einstein general relativity. This class is marked by a "non-polynomal" entire function (form factor), which…
These lectures are intended to give a pedagogical introduction to the main current picture of the very early universe. After elementary reviews of general relativity and of the standard Big Bang model, the following subjects are discussed:…