Francis Halzen Wins 2026 Nobel Prize in Physics for South Pole Neutrino Work

"Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument. His tenacity and scientific vision has paved the way for a new kind of astronomy," Mark Pearce, chair of the Nobel Committee for Physics, said in a news release.

Halzen spoke to the committee by phone from Italy. "It was a great surprise and I obviously didn't expect it," he said, adding that although his name had been raised as a possible laureate, the announcement still made him feel "strange," according to NPR News. The Associated Press said efforts to reach him were not immediately successful.

Born in Belgium, Halzen has been affiliated with the University of Wisconsin–Madison for decades. According to the Chinese science outlet QbitAI, he was born in 1944 in the Belgian town of Tienen, received his doctorate from KU Leuven in 1969 and joined the Madison faculty in 1972, where he worked on quarks, heavy particles and symmetry breaking in hadron physics. He is a co-author of the textbook "Quarks and Leptons."

IceCube is a research facility at the South Pole, with the University of Wisconsin–Madison as its lead institution. The detector consists of 86 cables holding 5,160 optical sensors, frozen into the ice between 1,450 and 2,450 meters below the surface, converting a cubic kilometer of natural glacier into a neutrino telescope.

The instrument addresses a long-standing problem: the highest-energy cosmic rays, believed to be protons flung out of natural particle accelerators, carry energies far beyond anything produced in terrestrial laboratories, but because they are charged they are twisted by interstellar magnetic fields and arrive at Earth from directions that reveal nothing about their source. Neutrinos carry no charge, pass through matter and magnetic fields without deflecting, and are produced alongside accelerated protons, which makes them point back toward their origin. They collide only rarely with atomic nuclei, producing charged particles and faint blue flashes of light that large, transparent volumes of sensors can record. QbitAI noted that trillions of neutrinos pass through the human body every second.

Halzen proposed in the 1980s that Antarctic ice serve as that volume, rather than deep ocean water, where bioluminescence and currents interfere. His team used heated water drills to melt holes about 2.5 kilometers deep and lowered sensor cables into them. QbitAI reported that an early pilot experiment, AMANDA, found that below roughly 1,400 meters the pressure crushes the tiny bubbles out of the ice, leaving it clear enough for light to travel about 300 meters. IceCube was completed in 2011.

In 2013 the collaboration announced the first clear detection of high-energy neutrinos from outside the solar system, work that won Physics World's Breakthrough of the Year award. Researchers later recorded 79 candidate neutrino signals from the direction of the active galaxy NGC 1068, also known as M77, and in 2023 produced the first image of the Milky Way's plane in high-energy neutrinos.

Halzen is not the only namesake of the project: QbitAI reported that a highland in Antarctica has been named Halzen Mesa.

The physics prize money this year is 12 million Swedish kronor, about $1.2 million, whether it goes to one laureate, several or an organization. Last year three scientists shared the physics prize for work on quantum tunneling, research that enabled ultra-sensitive MRI measurements and laid groundwork for better cellphones and faster computers. This year's announcements began Monday with the medicine prize, awarded to three scientists whose work produced a light-based tool for mapping how the brain works. The chemistry prize follows on Wednesday and literature on Thursday; after Friday's peace prize, the economics award will be announced Monday.