  A regular vacuum solution in 5D gravity on the principal bundle with the U(1)
structural group is proposed as a 4D wormhole. This solution has two null
hypersurfaces where an interchange of the sign of some 5D metric components
happens. For a 4D observer living on the base of this principal bundle this is
a wormhole with two asymptotically flat Lorentzian (Euclidean) spacetimes
connected by a Euclidean (Lorentzian) throat. The 4D Lorentzian observer sees
these two null hypersurfaces as electric charges.

General Relativity and Quantum Cosmology