A single high-energy particle might be a whisper from a vanishing ancient black hole

Ultra-high-energy cosmic rays carry millions of times more energy than particles in our most powerful accelerators. While most come from supernovae or active galaxies, some scientists believe these flashes could be the final screams of primordial black holes. These tiny, ancient objects are thought to have formed during the Big Bang and may be evaporating through a process called Hawking radiation.