Introduction

Two of the most challenging open problems in astronomy are the origin of the early universe supermassive black holes and the origin of multiple stellar populations in globular clusters. Both of these problems have been suggested to have solutions involving supermassive stars, which are stars that experience the general relativistic radial instability. We begin with a review of the history of the study of supermassive stars, and the motivation for studying them. Supermassive stars, however, are most likely to exist in the high redshift universe, and therefore they would be difficult to detect, though promising avenues such as strong lensing and gravitational waves from black hole formation are being pursued. In this thesis, we focus on a different method of detection, namely thermonuclear explosions occurring at the end of the lives of supermassive stars, events which have been termed general relativistic instability supernovae.