Belgian-American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his pioneering work on neutrinos, mysterious subatomic particles often described as “ghost particles.”
The Royal Swedish Academy of Sciences announced the award on Tuesday, October 6, recognising Halzen for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos originating from astrophysical sources.
Halzen, 82, is a professor at the University of Wisconsin-Madison and played a leading role in developing IceCube, a giant neutrino detector buried deep beneath the Antarctic ice at the South Pole.
The observatory uses thousands of light sensors embedded in roughly one cubic kilometre of clear Antarctic ice. When a neutrino occasionally interacts with matter, it produces a tiny flash of light that the sensors can detect and analyse.
Neutrinos are extremely difficult to detect because they have no electric charge, very little mass and interact only rarely with other matter. Huge numbers of them pass through Earth and the human body without being noticed.
Scientists are particularly interested in high-energy neutrinos because they can travel enormous distances from violent events in the universe while largely maintaining their direction. This allows researchers to use them as cosmic messengers to study distant galaxies and other powerful astronomical sources.
Halzen first proposed using the Antarctic ice as a giant neutrino detector in 1988. IceCube began operating in 2011, and researchers announced the first evidence of high-energy extraterrestrial neutrinos in 2013.
The observatory has since contributed to major discoveries, including evidence linking high-energy neutrinos to a supermassive black hole in another galaxy. In 2023, IceCube also produced the first neutrino-based image of the Milky Way.
Halzen said he was surprised by the Nobel announcement and described the recognition as unexpected. He also highlighted the collaborative nature of the IceCube project, which involved scientists, engineers and researchers from around the world.
The Nobel Committee said Halzen’s work helped establish neutrino astronomy as a new way of studying the universe. By detecting particles that cannot be observed through conventional telescopes, scientists can investigate cosmic events and environments that would otherwise remain difficult to study.
The 2026 physics prize therefore recognises not only the detection of elusive particles but also a new method of exploring the universe and understanding some of its most energetic phenomena.