Physicists leapfrog accelerators with ultrahigh energy cosmic rays

An international team of physicists has developed a pioneering approach to using Ultrahigh Energy Cosmic Rays (UHECRs)—the highest energy particles in nature since the Big Bang—to study particle interactions far beyond the reach of human-made accelerators. The work, outlined in the journal Physical Review Letters, makes use of UHECR measurements by the Pierre Auger Observatory (PAO) in Argentina, which has been recording UHECR data for about a decade.