Oh-My-God particle

On 15 October 1991 the Fly's Eye detector in the Utah desert recorded a single particle carrying about 3.2×10²⁰ electronvolts. That is tens of millions of times the energy of a proton in the Large Hadron Collider, and about the energy of a pitched baseball squeezed into one subatomic particle.

A cosmic ray detected in 2021 came close (about 2.4×10²⁰ eV), but the 1991 event remains the strongest recorded. Where it came from is still unknown.