STOCKHOLM — Belgian-American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin, the Royal Swedish Academy of Sciences announced on Tuesday.
The prize, awarded by the Academy, includes a 12 million Swedish kronor ($1.2 million) award, shared among laureates if applicable. Halzen, 82, is affiliated with the University of Wisconsin–Madison in the U.S., where he led the development of the IceCube Observatory at the South Pole.
Halzen’s work centers on detecting neutrinos, subatomic particles that carry information about violent cosmic events. These particles interact so rarely with matter that they are often described as “ghost messengers” from space. The IceCube Observatory, a cubic kilometer of Antarctic ice equipped with light sensors, captures these rare interactions, allowing scientists to trace neutrinos back to their distant sources.
Speaking to the Nobel Committee by phone shortly after the announcement, Halzen called the award “a great surprise” and “a great pleasure.” He added that while the possibility of winning had been discussed, the actual recognition felt “strange.”
The Nobel Committee highlighted Halzen’s “vision and scientific leadership” as fundamental to the observatory’s success. Professor Eva Olsson, a member of the Nobel Committee for Physics, described the IceCube as “a giant ice cube positioned at the South Pole” that enables the detection of neutrinos. Ellen Moons, secretary general of the Academy, emphasized that this year’s prize focuses on “ghostly messengers from space.”
Neutrinos are produced in extreme cosmic events, such as exploding stars or the cores of distant galaxies. Unlike light, which can be obscured by dust or other matter, neutrinos travel unimpeded across the universe, offering a direct window into these violent processes. The IceCube Observatory detects these particles when they occasionally interact with the ice, producing a telltale flash of light that sensors record.
Halzen first proposed the concept of detecting neutrinos at the South Pole in 1988, though many at the time doubted its feasibility. Reflecting on the project’s success, he noted, “I have to emphasize how lucky I was. Because when we started this project, everybody realized this was maybe a good idea, but very few thought it would work, including myself.”
The IceCube Neutrino Observatory is operated by an international team of researchers and engineers. Its thousands of sensors, drilled into the ice and frozen in place, form a 1km³ block of ice designed to capture these elusive particles. The observatory’s findings have opened new avenues in neutrino astronomy, allowing scientists to study cosmic phenomena that are otherwise invisible to traditional telescopes.
Halzen’s contributions extend beyond the observatory itself. His research has provided critical insights into the behavior of neutrinos and their role in the evolution of the universe. The Nobel Prize recognizes not only his technical achievements but also his long-term scientific vision, which has reshaped the field of astrophysics.
The announcement marks the latest in a series of Nobel Prizes honoring groundbreaking work in physics. The Nobel Prize in Physics is selected by the Royal Swedish Academy of Sciences and is one of the most prestigious awards in the scientific community.