Nonlinear electrodynamics in Bianchi spacetimes

We study the effects produced by nonlinear electrodynamics in spacetimes conformal to Bianchi metrics. In the presence of Born-Infeld-type fields these models accelerate, expand and isotropize. This effect is compared with that corresponding to a linear electromagnetic field; it turns out that for the same geometry, a Maxwell field does not favour inflation as much as a Born-Infeld field. The behaviour of the nonlinear radiation is analysed in terms of the equations of state. The energy conditions are analysed as well, showing that the Bom-Infeld field violates the strong energy condition.