It was predicted by Dirac, who dubbed it a "hole" of negative energy.
Myron Good argued that because there is insufficient CP violation in anomalous kaon regeneration, this material was not affected by gravity. The first example of it was discovered by Carl Anderson in observations of cosmic rays, and the ATHENA and ATRAP projects are attempting to isolate this material. It was predicted by Dirac, who dubbed it a "hole" of negative energy. For 10 points, name this material that undergoes annihilation when combined with regular matter.
Myron Good argued that because there is insufficient CP violation in anomalous kaon regeneration, this material was not affected by gravity.
antimatter [prompt on antiparticle]