The observed T-asymmetry of macroscopic physics is traced back to the extremely low entropy configuration of the early universe. Although matter was very hot and with a uniform temperature at that stage, the gravitational degrees of freedom were largely suppressed, which fact contributes to the lowness of the entropy and is encoded in the high level...
The standard cosmological model does not determine the spatial topology of the universe. This article revisits the signature of a non-trivial topology on the properties of the cosmic microwave background anisotropies. We show that the correlation function of the coefficients of the expansion of the temperature and polarization anisotropies in spher...
In this thesis, I will present a method I developped to treat cosmological perturbations at linear order, called the Effective Field Theory for Dark Energy (EFT of DE). It has the advantage of quantifying deviations from the standard model ΛCDM in compact and model independent manner. Secondly, I will discuss new theories that I discovered, that ex...
We present cosmological bounds on the thermal axion mass in an extended cosmological scenario in which the primordial power spectrum of scalar perturbations differs from the usual power-law shape predicted by the simplest inflationary models. The power spectrum is instead modeled by means of a "piecewise cubic Hermite interpolating polynomial" (PCH...
Published in International Journal of Theoretical Physics
We show that the Big Bang singularity of the Friedmann-Lemaître-Robertson-Walker model does not raise major problems to General Relativity. We prove a theorem showing that the Einstein equation can be written in a non-singular form, which allows the extension of the spacetime before the Big Bang. The physical interpretation of the fields used is di...
This article discusses aspects of culture-nature relations among indigenous groups in Southern Brazil. Based on the ethnography of Kaingang groups in the state of Santa Catarina, conceptions of culture and nature are considered taking into account the relationship between politics and cosmology. More specifically, this article focuses on the analys...
We propose that at the beginning of the universe gravity existed in a limbo either because it was switched off or because it was only conformally coupled to all particles. This picture can be reverse-engineered from the requirement that the cosmological perturbations be (nearly) scale-invariant without the need for inflation. It also finds support ...
We propose optimal estimators for bispectra from excited states. Two common properties of such bispectra are the enhancement in the collinear limit, and the prediction of oscillating features. We review the physics behind excited states and some of the choices made in the literature. We show that the enfolded template is a good template in the coll...
Published in Astrophysics and Space Science
Recent observational constraints from the Planck and Wilkinson Microwave Anisotropy Probe (WMAP) indicate tiny temperature anisotropies and some large angle anomalies in the Cosmic Microwave Background (CMB). These anisotropies may originated from an anisotropic geometric background, the matter distribution or both. In this paper we assume a homoge...
Published in Astrophysics and Space Science
I propose a new paradigm to understand expansion. In a non-preserving mass theory, space expansion is driven by a slow continuous mass (or energy) erosion process. I show that this proposal is formally equivalent to an additional cosmic “evolution” force, which was suggested previously to explain the flat rotation curves of spiral galaxies. The ene...
