The Status of Gravity as a Gauge Theory

Abstract

Einstein gravity (GR) is substantially different from the rest of physical interactions, the so called gauge interactions. The most clear difference is the major complexity of the field equation of Einstein gravity, which is the main obstacle for the application of the standard quantization techniques used in gauge theories. However, there is a deeper difference, which has nothing to do with the details of the field equations. This would be present even in any alternative gravity theory ruled by a modified Einstein equations, which could take into account quantum correction of a quantum gravity theory (not yet found) or, even at classical level, the contribution of a possible torsion of the spacetime. This difference has to do with the nature of the local invariance appearing in each theory...