Electromagnetic back-reaction from currents on a straight string
  Charge carriers moving at the speed of light along a straight,
superconducting cosmic string carry with them a logarithmically divergent slab
of electromagnetic field energy. Thus no finite local input can induce a
current that travels unimpeded to infinity. Rather, electromagnetic
back-reaction must damp this current asymptotically to nothing. We compute this
back-reaction and find that the electromagnetic fields and currents decline
exactly as rapidly as necessary to prevent a divergence. We briefly discuss the
corresponding gravitational situation.
