Spin in curved spacetime requires that the affine connection cannot be constrained to zero and its antisymmetric part, the torsion tensor, must be a variable in Hamilton's principle of stationary action which gives the field equations.

Torsion gives the correct generalization of the conservation law for the total (orbital plus intrinsic) angular momentum to the presence of the gravitational field, but also modifies the Dirac equation for fermions.

Popławski theorizes that torsion manifests itself as a repulsive force which causes fermions to be spatially extended and prevents the formation of a gravitational singularity within the black hole's event horizon.

[4] Because of torsion, the collapsing matter on the other side of the horizon reaches an enormous but finite density, explodes and rebounds, forming an Einstein-Rosen bridge (wormhole) to a new, closed, expanding universe.

Therefore, torsion might eliminate ultraviolet divergence and provide a physical mechanism for regularization in quantum field theory, giving finite values of bare quantities such as the mass and electric charge of the electron.