by gravitational torsion in the amplification of the magnetic fields,
in the same way was done with their amplification from metric
fluctuations, one considers that the torsion-free Riemannian tensor
vanishes. The plan of the Letter is as follows: In Section 2 we
consider the formulation of the Riemann–Cartan (RC) QED vacuum
electrodynamics, where torsion modes live in Minkowski–Cartan
spacetime background. In Section 3 the Riemann-flat case is presented
and geometrical optics in non-Riemannian spacetime along
with ray equations are presented. In Section 4 galactic magnetic
dynamos are obtained by Fourier analyzing the wave equations. In
this section Lorentz violation [8] originating from the presence of
a homogeneity growth of torsion modes induces a slower decay of
magnetic fields. The presence of the differential rotation and the
collapse of protogalaxies, act together to accelerate suppression of
the magnetic field decay and revert this process into a dynamo
amplification in galaxies. Section 5 contains conclusions and discussions.
2. Flat torsion modes QED in Minkowski–Cartan spacetime
Since the torsion effects are in general too weak [3,4], through