Francis Halzen awarded Nobel Prize in Physics 2026

SPIE as added its congratulations to Francis Halzen of the University of Wisconsin–Madison, USA, to whom the Royal Swedish Academy of Sciences last week presented the Nobel Prize in Physics 2026, “for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.” 

Neutrinos are chargeless, massless, particles that travel nearly at the speed of light. Found in every nook of the universe, they pass undetected through air as easily as they do through metal, without losing energy. These “ghost particles” hold keys to fundamental understandings of physics, yet their elusive qualities make them difficult to track. Very rarely, though, a neutrino will collide with an atomic nucleus, the interaction of which can be exposed with the right equipment. 

In 1988, Halzen presented his idea for capturing neutrinos in ice at the South Pole. With no geological interruptions, such as earthquakes, sensors placed in the pristine clarity of South Pole ice can track a flash of light that is produced when a neutrino collides with an atomic nucleus. His theory gained support and soon found its way to being tested with the creation of a unique telescope. 

The IceCube Neutrino Observatory, completed in 2011, covers a full cubic kilometer of ice and provides a near-full field of view of the sky. Because extremely high-energy neutrinos are extraordinarily rare, a large footprint is needed to improve the chances of capturing these collisions. The telescope can detect a wide range of neutrinos, from the highest to the lowest energies. 

Shortly after completion of IceCube, the first high-energy neutrinos were discovered, and researchers published their findings on neutrinos originating beyond the solar system. Halzen’s theory and leadership proved a visionary way to continuously record a previously imperceptible interaction that holds potential to reveal new understandings of the cosmos. 

Related SPIE content

• Halzen’s SPIE publications are available open access on the SPIE Digital Library
• IceCube particle detector in Antarctica records high-energy neutrinos
• Observing high-energy neutrinos with IceCube, by Francis Halzen