Francis Halzen won the 2026 Nobel Prize in Physics for creating an observatory that detects high-energy neutrinos. The award carries 12 million Swedish crowns ($1.2 million). On October 6, the Royal Swedish Academy of Sciences announced it was recognizing his “decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.”
Halzen, an 82-year-old Belgian-American particle physicist, is a professor at the University of Wisconsin–Madison in the United States. His project turned ice near the South Pole into a detector for particles that pass through Earth and human bodies without a trace. They interact with matter extremely rarely.
The observatory in the ice
Halzen first proposed capturing neutrinos at the South Pole in 1988. Completed in 2011 near the Amundsen-Scott South Pole Station in Antarctica, IceCube uses a cubic kilometre of pristine ice extending 2,500 metres below the surface. It registers about one high-energy neutrino per day.
Neutrinos are nearly massless and electrically neutral. Even strong magnetic fields don't deflect them. Unlike electromagnetic waves such as visible light, neutrinos arrive from directions that point straight back to their sources. That lets researchers study the processes that produced them.
The Royal Swedish Academy of Sciences said neutrino interactions in IceCube offer information about how high-energy neutrinos form and may uncover previously unknown phenomena. Researchers have traced the particles to sources both within and far beyond our galaxy. They hope to track them to exploding stars, gamma-ray bursts and cataclysmic events involving black holes and neutron stars.
“The messengers bring information from the cosmos,” Eva Olsson, of the Royal Swedish Academy of Sciences, said at a press conference. “They open the door to distant galaxies and tell us about the processes of exploding stars.”
Prize money and recognition
The Royal Swedish Academy of Sciences selects the Nobel physics prize. When more than one person receives it, the 12 million Swedish crowns are shared among the winners. Halzen was named the 2026 winner.
Swedish inventor and entrepreneur Alfred Nobel established the prizes in his will. His fortune came partly from inventing dynamite. First awarded in 1901, the prizes recognize achievements in science, literature and peace. Sweden's central bank later added the economics award. Nobel gave physics a prominent place in his will, and the prize remains one of the discipline's highest distinctions.
Albert Einstein, Marie and Pierre Curie, Max Planck and Niels Bohr are among the past physics laureates. The previous year's prize went to U.S.-based scientists John Clarke, Michel Devoret and John Martinis for experiments showing quantum physics in action. Their research was seen as helping advance the next generation of computing and other digital technologies.
The work still ahead
Halzen said success wasn't assured when the project began. “I have to emphasise how lucky I was because, when we started this project, everybody realised this was maybe a good idea, but very few thought it would work, including myself,” he told the press conference by telephone.
He said the main fruits of his discoveries still lay ahead. It was too early, he said, to know exactly what the method could reveal about the universe. “The real excitement is that I cannot answer that question yet,” he said. “This is just an introduction to the science, the astronomy is still to come.”
Smithsonian magazine dubbed Halzen “Neutrino Man” in 2014, when it gave him one of its Ingenuity Awards. The magazine praised an “amazing experiment (that) heralds the beginning of a new era in astronomy.” It also published a comic, “How One Physicist's Pursuit of the Cosmos Took Off in Antarctica.”
The physics award was the second Nobel announced that year, after Monday's medicine prize announcement; the chemistry prize was scheduled for Wednesday. Sweden's King Carl XVI Gustaf will present the Nobel medals at a ceremony in Stockholm on December 10. A banquet will follow at Stockholm City Hall. The peace prize is awarded separately in Oslo and is the only Nobel not presented in Sweden.