centra

What is the motivation for introducing gravitational actions containing quadratic curvature or other higher derivative terms in investigations of gravity? What is the classical and quantum interpretation of such actions and what are the prospects for their observational tests? In this talk we address these questions from one approach to quantum gravity: quantum geometrodynamics and its semiclassical limit. We shall draw attention to some conceptual and mathematical inconsistencies that quantum geometrodynamics and exact classical quadratic curvature gravity suffer from. We emphasize how one must be very cautious with classical and quantum interpretation of higher-derivative actions, if one wants to maintain a semiclassical limit to quantum geometrodynamics that is consistent with quantum field theory in curved spacetime. We hope to inspire the researchers to critically pursue this line of inquiry in other approaches to quantum gravity and their semiclassical limit, and especially to revisit the classical interpretation of higher-derivative gravitational actions.