New fields in general relativity

Abstract

One of the most exciting prospects in modern formulations of the general theory of relativity is the emergence of a new field which is created by the intrinsic spin of an elementary particle. In this development, this new field permeates space and produces forces and torques on other particles with spin. Thus spin is elevated to a similar status as mass and electric charge; each creates a field that interacts with other like particles. In this article, the basic notions of general relativity are reviewed and compared with the gauge principle of modern field theories. Motivation for the new spin field is given, several theories are compared, and future directions are given.