Research in Gravitational Physics

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This award is concerned with a broad range of research in gravitational physics, including research projects in classical general relativity and quantum field theory in curved spacetime. The main aim of this research is to obtain a deeper understanding of the implications of Einstein's theory of general relativity for phenomena involving black holes, as well as the nature of quantum phenomena in strong gravitational fields. The research will involve the direct participation of graduate students in all aspects of the research, and it will thereby contribute to their training. The areas of research associated with this award are of considerable interest to the public, and activities will be undertaken, such as giving public lectures, that aid in the dissemination of scientific knowledge to the public.The specific research topics proposed include: (i) an analysis of the quantum field infrared divergences associated with the classical memory effect, specifically (a) whether suitable "in" and "out" Hilbert spaces incorporating memory can be defined and (b) the decoherence effects of "soft gravitons"; (ii) an analysis of whether the quantum stress-energy tensor must always be singular on a Cauchy horizon, thereby enforcing strong cosmic censorship; (iii) an analysis of whether local and covariant "flow relations" can be obtained for the operator product expansion of interacting quantum fields; (iv) an analysis of the limitations on position measurements of a particle resulting from vacuum fluctuations of a quantum field with which it interacts; (v) an analysis of approximate Poincare invariance in discrete spacetime models; and (vi) an investigation of whether and how one can make sense of mathematically ill posed equations that are intended to represent effective field theories for alternatives to general relativity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.