  Some physical aspects of negative mass are examined. Several unusual
properties, such as the ability of negative mass to penetrate any armor, are
analyzed. Other surprising effects include the bizarre system of negative mass
chasing positive pass, naked singularities and the violation of cosmic
censorship, wormholes, and quantum mechanical results as well. In addition, a
brief look into the implications for strings is given.

General Relativity and Quantum Cosmology