Applications of quantum field theory in curved spacetimes

Abstract

While there is as yet no full theory of Quantum Gravity, some computations can still be performed in the regime where both gravitational and quantum effects are appreciable. These types of calculations, all of them perturbations, are performed in the hope they would provide guidance for the development of the full theory. This dissertation presents work related to three calculations using Quantum Field Theory in Curved Spacetimes. Primarily, the stress energy tensor of vacuum states is computed near Big Rip singularities, sudden singularities and in presence of a Schwarzschild-(anti) de Sitter black hole. Big Rip and sudden singularities are examples of future singularities that have been attracting interest because of their relation to the latest measurements that detected accelerated expansion of the universe. A Schwarzschild-de Sitter black hole is the ultimate compact object that forms in the presence of a cosmological constant. This dissertation also contains a theorem linking the appearance of sudden singularities with the type of fluid that would drive them.