Belgian Physicist Francis Halzen Wins 2026 Nobel Prize in Physics
Belgian particle physicist Francis Halzen, 82, has been awarded the 2026 Nobel Prize in Physics, the Royal Swedish Academy of Sciences announced on Tuesday. Halzen, a professor at the University of Wisconsin–Madison, received the prize as its sole laureate “for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.”
The award makes Halzen only the second Belgian ever to win the physics Nobel, after François Englert in 2013, and brings international recognition to a scientist who spent nearly four decades pursuing a vision first sketched out in 1988.
A Vision Buried in Antarctic Ice
Halzen realised that the ice at the South Pole could be used to track particles known as neutrinos. When a neutrino—very rarely—collides with an atomic nucleus, it produces a tiny flash of light that sensors embedded in the clear glacial ice can detect. The South Pole’s ice offers major advantages: it is free from various types of interference and the area is geologically stable, with no earthquakes.
Cosmic neutrinos with extremely high energies are very rare, so an enormous volume of ice is needed to observe an adequate number of collisions. IceCube covers an entire cubic kilometre of Antarctic ice and was completed in 2011. It uses more than 5,000 extremely sensitive light sensors distributed across the ice volume, according to Het Laatste Nieuws.
Researchers soon discovered the first high-energy neutrinos and, a few years later, published their discovery of neutrinos that must originate far outside our solar system. As Scientific American notes, these “ghostly particles from across the universe” may hint at exciting new physics.
Why Neutrinos Matter
Neutrinos are everywhere, but they do not make themselves known. They pass all the way through the Earth and through our bodies without us noticing. The Nobel Committee called them “ghostly messengers from the cosmos”—elusive particles that reach us without changing direction or losing energy.
That property makes them uniquely valuable. Scientists have long known that the cosmos contains natural particle accelerators firing out particles with energies up to a million times greater than can be achieved in laboratories on Earth. Because neutrinos travel in straight lines and arrive intact, they can reveal information about these violent cosmic settings that no other means can deliver.
“Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument,” said Mark Pearce, Chair of the Nobel Committee for Physics. “His tenacity and scientific vision has paved the way for a new kind of astronomy.”
From Tienen to the South Pole
Halzen was born in 1944 in Tienen in Belgium’s Flemish Brabant province. He earned his master’s degree and his PhD in 1969 from KU Leuven, with a thesis on the broken symmetries of hadrons. In the early 1970s he emigrated to the United States and joined the University of Wisconsin–Madison, where he has been a professor since 1977.
His path to physics was not inevitable. As La Libre recounted in a 2024 profile, Halzen could have spent his life as a secondary school science teacher in Landen after his physics studies in Leuven. Instead, he was offered a thesis position at the Catholic University of Leuven, a path that led to a stint at CERN in Geneva and then to Wisconsin.
In that same interview, Halzen reflected on the surreal arc of his career: “Toute cette aventure a été si surréaliste que pour moi, recevoir le prix Nobel ou pas, cela ne changerait rien”—“This whole adventure has been so surreal that, for me, whether or not I receive the Nobel Prize would not change anything.”
A Double Belgian Success
Tuesday’s announcement carried a distinctly Belgian flavour. Not only did the prize go to a Belgian, but the announcement itself was made by West Flemish professor Ellen Moons, Secretary-General of the Royal Swedish Academy of Sciences. She is the first woman ever to announce the Nobel Prizes for Physics, Chemistry and Economics, according to VRT NWS. Moons, who has lived in Sweden for 25 years, previously headed the Nobel Committee for Physics.
Halzen receives the full prize amount of 12 million Swedish kronor, roughly 1 million euros, as the sole laureate of this year’s physics prize. The announcement came during Nobel week, which runs from 5 to 12 October. Medicine was awarded on Monday, Chemistry follows on Wednesday, Literature on Thursday, Peace on Friday and Economics on 12 October.
Analysis: A Career Built on an Improbable Bet
Halzen’s recognition is notable not only for the science it celebrates but for the kind of science it rewards. IceCube was an audacious bet: a detector buried in a cubic kilometre of polar ice, built to catch particles that almost never interact with anything. For years, the project was a long shot, and Halzen’s willingness to champion an idea others might have dismissed is central to his legacy.
The discovery of astrophysical high-energy neutrinos opened an entirely new window on the universe. Traditional astronomy relies on light, radio waves and other electromagnetic signals; neutrino astronomy offers a complementary channel, one that can penetrate regions where light cannot escape. The neutrino interactions continuously collected by IceCube will provide researchers with novel knowledge about the violent settings in which high-energy neutrinos are created—and could even reveal previously unknown cosmic phenomena.
What’s Next
The physics Nobel has increasingly recognised the tools and techniques that underpin modern science, from attosecond electron motion to the foundations of artificial intelligence and macroscopic quantum phenomena. Halzen’s prize fits that pattern: it honours not just a discovery but the instrument and the decades of persistence that made it possible.
For Belgium, the award reinforces a strong scientific tradition. Halzen joins François Englert as only the second Belgian to take the physics prize, while Moons’s role as announcer underscores the growing visibility of Belgian and female leadership in global science.
Attention now turns to the rest of Nobel week—and to the ongoing work at the South Pole, where IceCube continues to watch for the rare flashes that carry news from the far reaches of the cosmos.