In February 2023, a detector 3.5 kilometres beneath the Mediterranean caught the aftermath of the most energetic neutrino ever seen — a 220-petaelectronvolt ghost particle, roughly 16,000 times beyond CERN’s strongest collisions, with no confirmed source anywhere in the sky.

In February 2023, a detector 3.5 kilometres beneath the Mediterranean caught the aftermath of the most energetic neutrino ever seen — a 220-petaelectronvolt ghost particle, roughly 16,000 times beyond CERN’s strongest collisions, with no confirmed source anywhere in the sky.

In February 2023, a single particle crossed a detector resting on the floor of the Mediterranean, and it carried more energy than any neutrino ever recorded. Two years of careful analysis later, the team behind the detector put a number on it: around 220 petaelectronvolts, roughly 16,000 times the energy of the most violent collisions produced at CERN’s Large Hadron Collider. It is the most energetic neutrino ever seen. No one knows where it cam…