Physical Review D - Particles, Fields, Gravitation and Cosmology vol. 70, no. 8, pp. 84001 - 1-084001-10
Analytic solutions are presented which describe the construction of a traversable wormhole from a Schwarzschild black hole, and the enlargement of such a wormhole, in Einstein gravity. The matter model is pure radiation which may have negative-energy density (phantom or ghost radiation) and the idealization of impulsive radiation (infinitesimally thin null shells) is employed.