I work on several aspects of gravitational physics: black holes, cosmology, quantum gravity phenomenology, stellar structure, modified gravity. In particular, I have worked in quantum field theory in curved space (black hole evaporation via Hawking radiation, the generation of primordial perturbations during inflation, quantum radiation by wormholes); the possibility of explaining the cosmic speedup and galactic dynamics problems in terms of extensions of General Relativity; in quantum gravity phenomenology and the notion of singularity; and in different issues related to extensions of General Relativity, from the weak field to the structure of compact objects alternative to black holes.