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Science|‘Ultrahigh Energy’ Neutrino Found With a Telescope Under the Sea
https://www.nytimes.com/2025/02/12/science/astrophysics-universe-neutrinos.html
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It’s the most energetic particle of its kind ever discovered, and scientists have no idea where it came from.
Katrina Miller studied neutrinos of much lower energies at the University of Chicago.
Feb. 12, 2025Updated 11:16 a.m. ET
Deep in the waters of the Mediterranean Sea, physicists have uncovered evidence of a ghostly subatomic particle catapulting through space at a speed they once could only dream of.
“What we have discovered is, we think, the most energetic neutrino ever recorded on Earth,” said Paul de Jong, a physicist at the University of Amsterdam and current spokesperson for the global collaboration of roughly 350 scientists who were involved in the discovery.
The team announced its “ultrahigh energy” neutrino on Wednesday, in a paper published in the journal Nature. The finding brings physicists and astronomers one step closer to understanding just what, exactly, is out there thrusting particles to such unfathomable speeds.
At a news conference on Tuesday, researchers described the discovery as a peek into what the universe looks like at its most extreme. “We’ve just opened a completely new window,” said Paschal Coyle, an astroparticle physicist at the Center for Particle Physics of Marseille in France. “It’s really a very exciting first glimpse into this energy regime.”
Neutrinos are notoriously antisocial. Unlike most other particles, they are nearly weightless and carry no electrical charge, so they do not regularly collide, repel or otherwise interact with matter. They flow through nearly everything — the innards of stars, the churning dust of galaxies, ordinary people — without a trace.
Thus unimpeded, neutrinos point straight back to their origins, making them excellent guides to the natural, yet-unknown “cosmic accelerators” that created them. They are also spectacularly elusive, and for decades scientists have worked to trap them with instruments deep in the mountains, beneath frozen lakes and buried in Antarctic ice.
But no neutrino captured previously has resembled anything quite like this one. Scientists found the ultrahigh energy neutrino using the Kilometer Cube Neutrino Telescope, or KM3NeT, which is still under construction but already operating. The instrument consists of a pair of detectors a couple of miles beneath the surface of the Mediterranean, off the coasts of France and Sicily.
