Gravitational Meissner Effect
  The gravitational analogue of the electromagnetic Meissner effect is investigated. Starting from the post-Newtonian approximation to general relativity we arrive at gravitational London equations, predicting a gravitational Meissner effect. Applied to neutron stars we arrive at a London penetration depth of 12km, which is about the size of a neutron star. 
R.P. Lano (The University of Iowa)