Anisotropic Born-Infeld Cosmologies

Anisotropic cosmological spacetimes are constructed from spherically symmetric solutions to Einstein’s equations coupled to nonlinear electrodynamics and a positive cosmological constant. This is accomplished by finding solutions in which the roles of r and t are interchanged for all r > 0 (i.e. r becomes timelike and t becomes spacelike). Constant time hypersurfaces have topology R × S and in all the spacetimes considered the radius of the two sphere vanishes as t goes to zero. The scale factor of the other dimension diverges as t goes to zero in some solutions and vanishes (or goes to a constant) in other solutions. At late times local observers would see the universe to be homogeneous and isotropic.