Gravitational Lensing as a Mechanism For Effective Cloaking
  In light of the surge in popularity of electromagnetic cloaking devices, we consider whether it is possible to use gravitational lensing to cloak a volume of spacetime. A metric for such a spacetime geometry is presented, and its geometric and physical implications are explained. 
Benjamin K. Tippett
gr-qc physics.optics physics.pop-ph