Quantum Field Theory is the fundamental theoretical framework of the Standard Model of elementary particles. This theory is formulated in a Minkowski space-time. However, the actual space-time metric is never of that type. On Earth, even at short distances, the metric is affected by both the force of the Earth’s gravity and the solar force, but especially by the acceleration of the Earth’s motion. At large distances the cosmological data lead one to think that, on average, the metric is of the Friedmann-Lemaitre-Roberson-Walker type.
The analysis of the quantization of fields in the presence of gravitational fields involves a number of theoretical issues that we intend to explore in this thesis; meaning how QFT can be adapted to introduce a gravitational background. The key aspects treated throughout this thesis include the mathematical background that will be used; scalar fields in expanding universes; thermal aspects of non inertial observers; and the renormalization problems regarding gravitational dynamics.