The properties of the energy-momentum tensor of a scalar field in various states against the backdrop of external gravitational fields

Excitations of quantum fields in curved space depend on the geometry of that space. As a result, the energies density of vacuum fluctuations are influenced by the background space. Such averages in the right-hand side of Einstein's equations can lead to a backreaction of the fields on the original geometry of space, causing its deformation. During the seminar, we will examine phenomena related to this effect. In particular, we will try to understand why quantum fluctuations lead to the evaporation of black holes.