Francis Halzen wins 2026 Nobel Prize in Physics for IceCube neutrino observatory

Belgian-American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos originating in space, the Royal Swedish Academy of Sciences announced Tuesday.

Halzen, 82, first proposed in 1988 that clear ice beneath the South Pole could be used to detect neutrinos, electrically neutral subatomic particles that have almost no mass and rarely interact with matter. The observatory, completed in 2011, uses more than 5,000 light sensors embedded in a cubic kilometre of Antarctic ice near the Amundsen-Scott South Pole Station. The sensors record flashes produced on the rare occasions when neutrinos collide with atomic nuclei.

Because neutrinos travel without changing direction or losing energy, scientists can trace them back to distant cosmic sources. IceCube has detected high-energy neutrinos from within and beyond the Milky Way, providing researchers with information about phenomena such as exploding stars and environments involving black holes and neutron stars.

The Nobel committee honored Halzen “for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.” The academy said the observatory had paved the way for a new kind of astronomy and could help reveal previously unknown phenomena.

“It was a great surprise, and I obviously didn’t expect it,” Halzen said by telephone during the announcement. A professor at the University of Wisconsin–Madison, he also credited the researchers who joined the project and helped build the observatory.