Quantum Gravity Foundations: UV to IR

Coordinators: Ben Freivogel, Steve Giddings, Ted Jacobson, Juan Maldacena

Scientific Advisors: Nima Arkani-Hamed, Tom Banks

The problem of reconciling quantum mechanics with gravity is one of the deepest unsolved problems of physics.  A lot of work has focused on short-distance (UV) manifestations of this problem such as perturbative nonrenormalizability and singularities, but has not arrived at a complete picture and has left many questions unanswered.  There has been a growing realization that there are important issues of principle that are not easily resolved merely via short distance modification of the general-relativistic spacetime description, but which pose long-distance (IR) quandaries that may drive closer to the conceptual core of the problem.  Notable among these are the fate of quantum information in the presence of black hole formation and evaporation, and the question of providing a quantum-mechanical description of cosmology.  There are multiple hints of deep connections between quantum information theory and gravity, and a possible emergent role for semiclassical spacetime, that could shed further light on these problems.  

This program will focus on these long-distance conceptual problems in quantum gravity, and different approaches to addressing them.  Specific topics to be explored include: 1) The question of describing the physics that unitarizes gravity in the regime where classical black holes form, and the closely connected question of elucidating the relationship between quantum information theory, gravity, and spacetime. 2) Connections between problems encountered in defining the quantum description for an evaporating black hole and for an inflationary cosmology, and between their possible resolution, including issues of defining local observables and measures which allow predictions to be made.  3) Study of proposals for a non-perturbative formulation of gravity, including AdS/CFT and other dualities, and other holographic or information-theoretic approaches.  4) Investigation of relationships between perturbative and nonperturbative problems of, and structures in, the gravitational S-matrix.