  The near-horizon region of magnetically charged black holes can have very
strong magnetic fields. A useful low-energy effective theory for fluctuations
of the fields, coupled to electrically charged particles, is force-free
electrodynamics. The low energy collective excitations include a large number
of Alfven wave modes, which have a massless dispersion relation along the field
worldlines. We attempt to construct traversable wormhole solutions using the
negative Casimir energy of the Alfven wave modes, analogously to the recent
construction using charged massless fermions. The behaviour of massless scalars
in the near-horizon region implies that the size of the wormholes is strongly
restricted and cannot be made large, even though the force free description is
valid in a larger regime.
