Neutrino hunter Francis Halzen wins 2026 Nobel Prize in Physics

The 2026 Nobel Prize in Physics has gone to Francis Halzen, the University of Wisconsin researcher who led the IceCube Neutrino Observatory at the South Pole to the first detection of high-energy neutrinos from beyond our solar system.

The Royal Swedish Academy of Sciences cited Halzen "for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin," according to the award announcement.

What neutrinos are, and why they matter

Neutrinos are the second most abundant particles in the universe after photons, the particles that make up light. But they earn their nickname "ghost particles" because they almost never interact with anything. About 100 trillion neutrinos pass through your body every second; over a lifetime, maybe one of those will hit an atom.

They have no electric charge, almost no mass, and move at nearly the speed of light, passing through matter as if it were empty space. That makes them extremely hard to detect — but also makes them perfect cosmic messengers. High-energy neutrinos are thought to come from violent events such as collapsing stars or jets from black holes. Unlike light, neutrinos reach Earth without changing direction or losing energy, carrying information no other particle can.

Building a detector in Antarctic ice

Halzen realized in 1988 that the ice at the South Pole could serve as a neutrino detector. The ice is clear, free of interference, and not disturbed by earthquakes. IceCube is a cubic kilometer (0.62 cubic miles) of that ice, fitted with light sensors that watch for tiny flashes when a neutrino rarely interacts with another particle.

Data collection began in 2005, and the observatory was completed in 2011. In August 2011 and January 2012, the team detected the first hints of astrophysical neutrinos, which they named "Bert and Ernie." By November 2013, they had announced 26 more.

What the prize means for astronomy

IceCube is still collecting data, and its discoveries have opened a new window on the cosmos. "Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument," Mark Pearce, chair of the Nobel Committee for Physics, said in the announcement. "His tenacity and scientific vision have paved the way for a new kind of astronomy."

• astrophysics
• Francis Halzen
• IceCube Neutrino Observatory
• neutrinos
• Nobel Prize in Physics
• South Pole