Francis Halzen Wins 2026 Nobel Physics Prize for Antarctic Neutrino Work
University of Wisconsin-Madison physicist Francis Halzen has won the 2026 Nobel Prize in Physics for leading the IceCube Neutrino Observatory and helping trace high-energy astrophysical neutrinos to cosmic sources.
IceCube is embedded in a cubic kilometer of Antarctic ice and uses thousands of light sensors to survey the universe for neutrinos, nearly massless particles that rarely interact with other matter. Neutrinos provide information about the workings of black holes, galaxies and other objects in the cosmos.
"IceCube is like no other telescope in the world," UW-Madison interim Chancellor Eric M. Wilcots said in the report. "And there is no other scientist quite like Francis Halzen, whose idea to create a neutrino detector under almost a mile of ice has led to a remarkable multinational and multi-institutional scientific collaboration and a fundamental shift in how we think about the universe."
The report explains why neutrinos are useful for astronomy. Unlike the neutral neutrino, cosmic rays are charged particles whose paths cannot be traced directly back to their sources. But the powerful cosmic accelerators that produce them, such as supermassive black holes, also produce neutrinos. These so-called "ghost particles" travel nearly undisturbed from their accelerators, giving scientists an almost direct pointer to their source.
Along with observations by other telescopes, the neutrino first detected by IceCube provided the first-ever evidence of a source of high-energy cosmic rays. The origins of cosmic rays had been notoriously difficult to pinpoint since their discovery more than 100 years ago by Victor Hess, the 1936 physics Nobel laureate.