Semiclassical gravity and applications to Cosmology

Abstract: We review some conceptual problems in quantum theory, their repercussions in the way we treat the gravitation/quantum interface emphasizing the manner in which they occur in the cosmological context. We will consider in particular issues arising in the discussion of inflation, such as the emergence of the seeds of cosmic structure, the predictions for generation of primordial gravity waves, and  the problem of eternal inflation, where we find that the approach we advocate results in substantial departures from the findings obtained in the more traditional treatments.