Avoidance of singularities in spherically symmetric charged dust

Abstract

In spherically symmetric charged dust, just like in electrically neutral dust, two kinds of singularity may be present: the Big Bang/Crunch (BB/BC) singularity, and shell crossings. Quite unlike in neutral dust, the BB/BC singularity may be avoided. When the absolute value of the charge density r is everywhere small compared to the mass-energy density d (|r| < D = \sqrt{G} d / c^2), the conditions that allow the model to avoid the BB/BC singularity necessarily lead to shell crossings. There exist sets of initial conditions that allow us to avoid both singularities (when either |r| > D everywhere, or |r| = D at the center of symmetry while |r| < D elsewhere). In those cases, both kinds of singularity may be avoided for a sufficiently long period that a body of charged dust may go through the tunnel between the singularities in the maximally extended Reissner -- Nordstrom spacetime, to emerge into another asymptotically flat region. An explicit example of such a configuration is presented and discussed. It does not contradict any astrophysical constraints.