Francis Halzen won the 2026 Nobel Prize in Physics on October 6 for conceiving and leading IceCube, the South Pole observatory that opened a new way to detect high-energy cosmic neutrinos and investigate the universe’s most violent environments.
The Royal Swedish Academy of Sciences honored Halzen, a Belgian-American physicist at the University of Wisconsin–Madison, for his “decisive contributions” to IceCube and the discovery of neutrinos originating beyond the solar system. IceCube uses thousands of light sensors embedded in roughly one cubic kilometer of Antarctic ice to record faint flashes produced when neutrinos collide with atomic nuclei. Because neutrinos have no electric charge and rarely interact with matter, they can travel across enormous distances without being deflected or losing much energy.
That makes them valuable messengers from places such as supermassive black holes and other natural particle accelerators. Halzen first proposed using South Pole ice for neutrino detection in 1988, and IceCube was completed in 2011 after years of international engineering and scientific work. The observatory announced its first evidence of astrophysical neutrinos in 2013, helping establish neutrino astronomy as a new field.
Researchers say IceCube’s continuing observations could identify more cosmic sources and reveal previously unknown phenomena.