Nobel prize in physics goes to Francis Halzen for south pole work on neutrinos

The IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station, in Antarctica. Photograph: Felipe Pedreros/IceCube/NSFView image in fullscreenThe IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station, in Antarctica. Photograph: Felipe Pedreros/IceCube/NSFNobel prize in physics goes to Francis Halzen for south pole work on neutrinosBelgian physicist praised for work on the IceCube detector that observes the ghost-like particles in Antarctica

The Nobel prize in physics 2026 has been awarded to a researcher who turned an enormous block of ice at the south pole into a detector for ghostly particles called neutrinos that reach Earth from outer space.

Prof Francis Halzen, a Belgian particle physicist at the University of Wisconsin-Madison, led work on the IceCube neutrino observatory, which made the first detection of high-energy extraterrestrial neutrinos in 2013, soon after it switched on.

To build the observatory, scientists, technicians and engineers embedded thousands of basketball-sized light detectors into a cubic kilometre of ice to detect faint flashes of light that can result when neutrinos from space crash into atomic nuclei.

Announcing the prize on Tuesday, the Nobel committee said Halzen won “for decisive contributions to the IceCube neutrino observatory and the discovery of high-energy neutrinos of astrophysical origin”. He receives a prize of 12m Swedish kronor (about £900,000).

“It feels strange,” Halzen told a press briefing on winning the prize. “I hope it reflects on the really courageous people who joined me in the beginning of this project when no really respectable, conservative physicist would have joined me, but many talented people did.”

View image in fullscreenFrancis Halzen speaking in 2018. He received the news of his Nobel win while travelling in Italy. Photograph: Reuters TV/ReutersNeutrinos are mysterious particles that are as elusive as they are ubiquitous. They pass through almost everything they encounter, from people to planets. But every now and then, a neutrino will interact with the nucleus of an atom in a collision that can be picked up by a sensitive detector.

Halzen realised that brief flickers of light from neutrino collisions could be detected in clear, glacial ice and in 1988 put forward a plan to convert a chunk of the south pole into a neutrino observatory. Apart from a hostile environment for the team, the site benefited from being far from sources of interference and the risk of vibrations from earthquakes.

After the first detection of high-energy extraterrestrial neutrinos in 2013, scientists working on IceCube identified the first cosmic source of neutrinos 3.7bn years away.

The observatory has paved the way for a new kind of astronomy. Until now, researchers have learned about the cosmos from light, other electromagnetic radiation, and gravitational waves. Neutrinos are considered messengers from the cosmos and provide fresh clues as to how the universe evolved.

Halzen, who received the news while travelling in Italy, said he was working on a new proposal and hoped that winning the prize would help in getting it approved.

Dr Patrick Dunne at Imperial College London welcomed the prize. “For all of human history the only way we’ve been able to understand things outside our solar system is with light. Detecting neutrinos from astrophysical sources opens up a new lens, so it isn’t overstating things to liken this to when Galileo first pointed a telescope at the stars,” he said.

“Neutrinos are the most abundant massive particles and their ability to pass through matter much more easily than light makes them ideal for observing distant phenomena or the inside of extreme phenomena like those seen by IceCube,” he added.

Other experiments to understand neutrinos include the Deep Underground Neutrino Experiment (Dune) in the US and the Hyper-Kamiokande detector in Japan.

The observations of cosmic neutrinos have led some scientists to speculate that the ghostly particles could be used by alien civilisations to send messages across the universe. Asked what he made of the idea, Halzen said: “I don’t think I’ll go there. We have enough realistic problems to deal with right now [to] make neutrino astronomy a reality rather than worry about this.”

But he added that when astronomers have opened new windows on the universe, they often make unexpected discoveries. “I’m sure this will be true for neutrinos 50 years from now,” he said.

On Monday, three scientists won the Nobel prize in medicine for optogenetics, a powerful technique that has allowed researchers to shed unprecedented light on the workings of the brain. The Nobel prize in chemistry is announced on Wednesday.