Institute for Advanced Study/Princeton University Joint Astrophysics Colloquium

The predictions of General Relativity (GR) have been confirmed to a remarkable precision in a wide variety of tests. In addition, consistent and well-motivated modifications of the theory of GR have been notoriously difficult to obtain. However, in recent years a compelling modification has been shown to be free of the traditional pathologies. This is the theory of massive gravity, in which the graviton has a small mass. In this talk I will give a general review of massive gravity, discuss potential observational signatures and present the current challenges facing this theory.