“When I first discovered this ultra-high-energy cosmic ray, I thought there must have been a mistake, as it showed an energy level unprecedented in the last 3 decades,” shared Professor Fujii.

Such an energy level is comparable to that of the most energetic cosmic ray ever observed, dubbed the “Oh-My-God” particle, which had an estimated energy of 320 EeV when detected in 1991.

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“No promising astronomical object matching the direction from which the cosmic ray arrived has been identified, suggesting possibilities of unknown astronomical phenomena and novel physical origins beyond the Standard Model,” Professor Fujii mused.