Particles arrive at earth from space with energies as great as 50 joules, a macroscopic energy in a microscopic particle. It is not understood how nature can accelerate particles to such energies.
Such remarkable events occur rarely, about one per kilometer squared per century. Recently a cosmic ray observatory has been built in Argentina that covers an area of 3000 square kilometers.
This Pierre Auger Observatory is a collaboration of 16 countries.
Excellent data has been collected since January 2004. The details of the observatory will be described. The most significant results will be reported.