Oh-My-God Particle

The Oh-My-God Particle was an energetic cosmic-ray particle detect in 1991, with an energy of 3.2×10²⁰eV, more than a million times more energetic than any other particle detected at the time and a hundred times that of any particle produced before or since by an Earth accelerator. It has been an instigator of theories of its origin and efforts to detect more. As it was above the GZK limit, that appears to suggest some limit on the distance to its source. As published in 11/2023, the 1991 detection still holds the record, but additional particles with energy within an order-of-magnitude have since been detected (e.g., the Amaterasu particle captured in 2021), which help confirm the 1991 detection. The Pierre Auger Observatory and the Telescope Array Project are efforts to detect more.