Modave Lectures on Horizon-Size Microstructure, Fuzzballs and Observations

Abstract

These lecture notes discuss various aspects of the fuzzball paradigm, microstate geometries, and their role in gravitational phenomenology. We briefly introduce the information paradox and discuss how the fuzzball paradigm aims to resolve it. Then, some important families of fuzzball solutions in supergravity, called microstate geometries, are explored: multi-centered bubbling geometries and superstrata. Finally, we will review some very recent developments of the phenomenology of fuzzballs and delineate the exciting opportunities as well as the limitations of studying fuzzballs as alternatives to black holes in current and future observations.