Neutrino Giant: A Message from an Era When the Universe Was 10 Billion Times Hotter
In February 2023, the KM3NeT underwater telescope, anchored at a depth of three kilometers off the coast of Sicily, registered a flash. A single muon streaked through the detector, leaving a trail of energy at 220 petaelectronvolts. That's like a mosquito punching through a concrete wall in mid-flight.