"The Highest-Energy Cosmic Rays"
results on the highest energy cosmic rays indicate that
the cosmic rays spectrum continues well beyond 10^20 eV. Because cosmic
hadrons should interact inelastically with 2.7 deg black body radiation
at these energies, the sources of these particles must be relatively
local - within 50 Mpc. No astrophysically interesting candidate sources
such as AGN's have been identified in the direction error boxes of these
particles. The origin of the highest energy particles in nature thus
remains a mystery. These results and plans for new experiments to study
this mystery with much better sensitivity will be presented.