Searching for Exotic Particles from Cosmic-Ray Collisions

Our planet is constantly bombarded with cosmic rays. Most collide with atoms in our atmosphere, producing sprays of particles that fall to the ground, thousands striking each square meter every second. Cosmic rays with extremely high energies are infrequent, but their interactions in the atmosphere open a tiny but important window to ultra-high-energy physics – a window that even the most advanced particle accelerators are incapable of achieving. Recently, three physicists took a peek in.