Quantum mechanical fingerprints in gravity theories

We study aspects of quantum effects in connection with gravity theories and discuss their implications. The starting point are several classical aspects of gravity and cosmology, with emphasis on the analytical solvability of the Friedmann equations. We include the exact solution of these equations for a Universe with positive and negative Cosmological Constant {lambda}. We study the effect of a time dependent cosmological constant due to a false vacuum state, which can be a manifestation of Quantum Mechanics. On the evolution of the Universe, we discuss the transition region from radiation domination to dust domination, which in standard cosmology refers to the early and the late Universe respectively. While in the standard cosmology the simplest model of the Universe is to assume that it behaves as a perfect fluid, there is one type of viscosity, the shear viscosity, which several authors claim cannot be zero due to Quantum Mechanical effects. Motivated by this we study the implications of an early Universe filled with Quark Gluon Plasma which has non-zero viscosity due to quantum effects. We take into account separately both viscosity coefficients, the shear and the bulk viscosity. In general we find the possibility of non-singular Universes due to viscosity effects. Our next field of investigation is torsion in gravity theories, motivated by the fact that one part of torsion is attributed to spin, and thus to a quantum mechanical quantity. We apply effects of torsion to Cosmology, and we study non-singular and inflationary models which come out from this inclusion. The next Quantum effect which we probe into is the hbar-correction to the Schwarzschild metric, obtained from corrections to the Newtonian potential. We discuss the corrections which get generated upon the Bekenstein entropy of a Black Hole. We apply this hbar-correction to Newtonian Cosmology and study its effects on the evolution of the early Universe, here we find non-singular rebouncing Universes

• Autores: Bravo Medina, Sergio
• Tipo de recurso: Doctoral thesis
• Fecha de publicación: 2017
• Institución: Universidad de los Andes
• Repositorio: Séneca: repositorio Uniandes
• Idioma: eng
• OAI Identifier: oai:repositorio.uniandes.edu.co:1992/38753
• Acceso en línea: http://hdl.handle.net/1992/38753
• Palabra clave: Gravedad cuántica - Investigaciones; Teoría cuántica - Investigaciones; Cosmología - Investigaciones; Squarks - Investigaciones; Gluones - Investigaciones; Física
• Rights: openAccess
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/