Classical and Quantum Gravity

One of the most fundamental and universal forces of nature is gravity. Not only does it describe falling apples, the orbits of planets and the bending of light, but it also responsible for extreme physical phenomena nature. These including the creation of mysterious objects like black holes, the emission of Gravitational Waves in violent astrophysical processes and the evolution of the universe itself.

Einstein’s celebrated theory of general relativity provides the best description so far of gravitational interactions. However, for several reasons general relativity is considered to be incomplete, so that new theoretical approaches combined with observational efforts are needed. This leads one to consider alternative or more general theories that modify general relativity along with studies of various limits of General Relativity, e.g. non-relativistic as well as ultra- local limits. In particular, new insights can be gained by probing the strong gravity regime in which General Relativity is pushed to its limits, such as around black holes and neutron stars. The spectacular images of a black hole from the Event Horizon and the detection of Gravitational Waves, are providing an exciting window in which fundamental aspects of gravity are expected to be revealed by experiment.

Confronting general relativity with quantum mechanics, and constructing a full-fledged theory of quantum gravity is another important outstanding goal. This includes finding the answer to profound questions implied by the black hole information paradox and uncovering a microscopic understanding of black hole entropy. Here, the concept of Holographic Duality which relates strongly gravitating systems to field theories, is a promising road to gain new insights. More generally, research at Nordita comprises different and diverse approaches to these fundamental problems in gravity, connecting also to the the research directions pursued in the High Energy Theory group as well as those studied in the Astrophysics group.