Nonlinear electrodynamics and FRW cosmology
  Maxwell electrodynamics, considered as a source of the classical Einstein field equations, leads to the singular isotropic Friedmann solutions. We show that this singular behavior does not occur for a class of nonlinear generalizations of the electromagnetic theory. A mathematical toy model is proposed for which the analytical nonsingular extension of FRW solutions is obtained. 
V.A. De Lorenci, R. Klippert (EFEI/Itajuba), M. Novello, J.M. Salim   (CBPF)