ABSTRACT
In this chapter we will develop the problem of quantum gravity and will show, in this regard, how it is important in the consideration of geometric algebra.
For this purpose we will discuss, first, the introduction of spin in the Einstein equations of general relativity. For that reason we begin by considering the Einstein-Cartan theory, i.e., general relativity plus torsion, which, from the physical point of view, means the introduction of spin in the theory of gravity.
