Nobel physics prize awarded for detection of cosmic neutrinos

Belgian-born physicist Francis Halzen has won the 2026 Nobel Prize on Physics for his work in detecting high-energy elusive particles called neutrinos that come from deep in space.

His pioneering contribution is the founding of a giant detector, the IceCube Neutrino Observatory, at the South Pole. Its results have helped to found the fields of neutrino and multimessenger astronomy, which help physicists to unlock the mysteries of the Universe through observing highly energetic events from deep in the cosmos.

Halzen, who is based at the University of Wisconsin–Madison, takes home all of the 12-million Swedish kronor (US$1.2-million) prize, announced by the Royal Swedish Academy of Sciences in Stockholm on 6 October. It is the first time since 1992 that the the physics prize has been awarded to only one winner.

“It was a great surprise and I obviously didn’t expect it,” said Halzen, speaking to the Nobel press conference after the prize was announced. “This reflects on the really courageous people who joined me in this project when really no respectable conservative physicist would have joined me, but many talented people did and that’s why I’m here.”

Neutrinos are the second most common particle in the Universe, after photons. More than 1 billion neutrinos pass through a hand every second, but high-energy neutrinos are extremely rare and hard to detect. IceCube was designed to study the particles when they fly out of some of the most energetic environments in the Universe, such as supernovae and γ-ray bursts. Because neutrinos pass straight through matter, they provide a straight line back to these events, providing researchers with a unique way of probing astrophysical phenomena.

Halzen is “a father figure for neutrino astronomy”, says Paschal Coyle, a neutrino physicist at Aix-Marseille University in France and the spokesperson of KM3NeT, a similarly large observatory being built in the Mediterranean Sea.