### Conveners

#### [QC] Quantum gravity and cosmology: Part I

- Mariam Bouhmadi-Lopez

#### [QC] Quantum gravity and cosmology: Part I

- Mariam Bouhmadi-Lopez

#### [QC] Quantum gravity and cosmology: Part II

- There are no conveners in this block

We try to convince the reader that the categorical version of differential geometry, called Synthetic Differential Geometry (SDG), offers valuable tools which can be applied to work with some unsolved problems of general relativity. We do this with respect to the space-time singularity problem. The essential difference between the usual differential geometry and SDG is that the latter enriches...

On this talk, we will present classical dark energy models that induces abrupt cosmic events in the future. These events are intrinsic to phantom-like matter, we will as well present the cosmological pertubations of these models. We will also briefly comment on the quantisations of these models. Mariam Bouhmadi-López will give more details on the quantum cosmology of these models.

On this talk, we will present a review on dark energy singularities and abrupt events. We will start with a classical description of several models. On the second part of the talk, we will focus on the quantum analysis of these singularities/abrupt events. The analysis will encompass also modified theories of gravity.

We discuss the classical and quantum cosmology of a universe filled

with a tachyon condensate and other Born-Infeld type fields. We analyse,

in particular, the cases with a constant potential and with an

inverse square potential. We apply the Wheeler-DeWitt equation of

canonical quantum gravity to these models and show how it can be

appropriately reformulated as a difference equation.

In recent years the idea that not only the configuration space of particles, i.e. spacetime, but also the corresponding momentum space can have a nontrivial geometry has attracted significant attention, especially in the context of quantum gravity. The aim of the talk is to discuss extension of this concept to the domain of field theories, the so-called Nonlinear Field Space Theory (NFST)....

The power spectrum of inflationary gauge-invariant perturbations is computed in the context of canonical quantum gravity for generic slow-roll models. A semiclassical approximation, based on an expansion on inverse powers of the Planck mass, is applied to the complete Wheeler-DeWitt equation describing a perturbed inflationary universe. This expansion leads to a hierarchy of equations at...

We discuss the primordial power spectra for both scalar and tensor perturbations in a inflationary model quantized by means of the hybrid quantization in Loop Quantum Cosmology. In order to compute the primordial power spectra we use the effective dynamics coming from the quantum theory and we neglect backreactions. As expected, the primordial power spectra obtained depend crucially in the...

The quantum bounce a priori connects several (semi)classical epochs of Universe evolution,

however determining if and how well the semiclassicality is preserved in this transition

is highly nontrivial. We review the present state of knowledge in that regards in the

isotropic sector of loop quantum cosmology. This knowledge is next extended by studies

of an isotropic universe admitting...

Blackbody radiation contains (on average) an entropy of 3.9+-2.5 bits per photon. This applies not only to provervial case of “burning a lump of coal”, but also to the Hawking radiation from black holes. The flip side of this observation is the information budget: If the emission process is unitary, as it certainly is for normal physical burning, then this entropy is exactly compensated by the...

The talk will be based on a joint work with M. Eckstein (arXiv:1510.06386), in which we propose and study an extension of the causal precedence relation onto the space of Borel probability measures on a given spacetime. The developed formalism draws from the mathematical theory of optimal transport and rigorously codifies the intuition of a subluminal probability flow. This will be illustrated...

Drawing from the mathematical richness of noncommutative geometry, I will introduce the concept of an "almost commutative space-time" and show that it admits a sensible notion of causality. The latter does not affect classical causal relations in the space-time component, but it does induce highly non-trivial constraints on the "motion" in the "inner space". I will illustrate the general...

Recently we proposed a cosmological model based on smooth 4-manifolds admitting non-standard smoothness structures. The manifolds are so-called exotic versions of $\mathbb{R}^4$ ($R^4$) and $S^3\times \mathbb{R}$. This model has been developed further and we have shown how to derive some realistic cosmological parameters from these exotic smoothings in a new way. Besides, we indicated the...