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 Born–Infeld field violates the strong energy condition.