  In quantum electrodynamics, Schwinger showed in 1951 that in a uniform
electric field the vacuum may spontaneously produce electron-positron pairs.
For this to occur, the required electric field is exceptionally large, $\sim
10^{18}$ N/C. In the Electromagnetically Accelerating Universe (EAU) model,
such an electric field would be undesirable because it discharges the
Primoridal Extemely Massive Naked Singularities (PEMNSs) whose mutual repulsion
causes the acceleration. This leads to a constraints on the charges and masses
of the PEMNSs which must be satisfied in an EAU model.
