Francis Halzen Wins 2026 Nobel Prize in Physics for IceCube
Roughly 100 trillion neutrinos pass through your body every second. Almost none of them tell astronomers anything about the violent universe. A physicist figured out how to catch the rare ones that do.
On October 6, the 2026 Nobel Prize in Physics was awarded to Francis Halzen, a theoretical physicist at the University of Wisconsin-Madison, for his role in developing a massive observatory that detects high-energy neutrinos. Halzen was born in Belgium in 1944 and has spent most of his career in the American Midwest. He receives the full prize, the first time since 1992 that the Physics Nobel has gone to a single person, according to Smithsonian magazine.
Two kinds of ghost particle
Neutrinos are electrically neutral, nearly massless particles that seldom interact with ordinary matter. The 100 trillion figure refers mostly to low-energy neutrinos, produced by everyday astrophysical processes such as nuclear fusion in the Sun. IceCube hunts something else: rare, high-energy neutrinos made by the most violent processes in the universe, including exploding stars and black holes feeding on matter. These particles can be traced back to the distant objects that produced them.
A telescope made of ice
In the 1980s, Halzen proposed using Antarctic ice as the detector. When a neutrino hits an atom, it produces a faint flash of light, and deep Antarctic ice is completely dark, with no large animals, little radioactivity and no earthquakes. IceCube was finished in 2011. It is a cubic kilometer of ice with 5,160 light sensors on strings that run through 86 boreholes to depths of roughly 8,000 feet.
In 2013, the collaboration reported its first evidence of high-energy neutrinos from beyond the solar system. Later observations traced neutrinos to the Milky Way and several other galaxies. The Nobel committee chair, Mark Pearce, said Halzen’s tenacity and scientific vision paved the way for a new kind of astronomy. Halzen said that when the project started, few people thought it would work, himself included.
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