Belgian American physicist Francis Halzen has won the 2026 Nobel Prize in Physics for pioneering a way to study some of the universe’s most mysterious particles and using them to look deeper into the origins of cosmic phenomena.
Halzen, 82, a professor at the University of Wisconsin-Madison, was recognized for his work behind IceCube, a massive neutrino observatory built deep beneath the Antarctic ice at the South Pole. The experiment has opened a new way of observing the universe by detecting high-energy neutrinos, particles so difficult to capture that they are often called “ghost particles.”
Unlike ordinary matter, neutrinos have no electric charge and interact with matter only very rarely. Neutrinos are constantly moving through Earth and our bodies, rarely interacting with the matter they encounter.
What makes them especially valuable to scientists is that their paths are not bent by magnetic fields. Unlike light and other electromagnetic signals, neutrinos can travel across the universe while retaining information about where they came from.
“The messengers bring information from the cosmos,” Eva Olsson of the Royal Swedish Academy of Sciences said during the Nobel announcement. She said neutrinos offer scientists a way to study distant parts of the universe and uncover the powerful cosmic events that produce them, including exploding stars.
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Halzen’s idea was to use the enormous amount of clear ice at the South Pole as a natural particle detector. He first presented the concept in 1988 and spent years building support for an experiment that many researchers considered highly ambitious.
The IceCube observatory was eventually completed in 2011. It now occupies roughly a cubic kilometer of Antarctic ice, with detectors extending about 2,500 meters below the surface near the Amundsen-Scott South Pole Station.
When a neutrino happens to collide with another particle inside the ice, the interaction produces a small flash of light. IceCube’s thousands of sensors can detect these flashes and help scientists determine the direction and energy of the neutrino.
The observatory typically detects about one high-energy neutrino a day. Those rare detections can help scientists trace the particles back to some of the most powerful objects and events in the universe, including exploding stars, gamma-ray bursts, black holes and neutron stars.
The findings have already shown that high-energy neutrinos come from sources both inside and far beyond the Milky Way. Scientists hope that studying these particles will eventually reveal how some of the universe’s most energetic phenomena produce them.
Halzen has acknowledged that the experiment was far from a guaranteed success when he proposed it.
“I have to emphasize how lucky I was because, when we started this project, everybody realized this was maybe a good idea, but very few thought it would work, including myself,” he told reporters by telephone after the Nobel announcement.
The recognition is not Halzen’s first major honor for his work on neutrinos. In 2014, Smithsonian magazine named him “Neutrino Man” as part of its Ingenuity Awards and praised the Antarctic experiment as the beginning of a new era in astronomy. The magazine even published a comic tracing how his pursuit of the cosmos led him to the South Pole.
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For Halzen, however, the most important discoveries may still lie ahead.
He said scientists are only beginning to understand what neutrino astronomy could reveal about the universe and that it is too early to predict the full impact of the method.
“The real excitement is that I cannot answer that question yet,” Halzen said. “This is just an introduction to the science, the astronomy is still to come.”
The 2026 Nobel Prize in Physics carries a total award of 12 million Swedish crowns, or about $1.2 million, which is divided if more than one laureate is selected.
The Nobel Prize in Physics is among the most prestigious honors in science. Established through the will of Swedish inventor and entrepreneur Alfred Nobel, the awards have recognized scientists whose discoveries have fundamentally changed how humanity understands the natural world.
Previous physics laureates include Albert Einstein, Marie Curie, Pierre Curie, Max Planck and Niels Bohr.
Last year, the physics Nobel was awarded to U.S.-based scientists John Clarke, Michel Devoret and John Martinis for experiments demonstrating quantum mechanical effects in electrical circuits, work that could have implications for future computing and digital technologies.
Halzen and the other Nobel laureates will receive their medals from Sweden’s King Carl XVI Gustaf during a ceremony in Stockholm on Dec. 10, the anniversary of Alfred Nobel’s death. The ceremony will be followed by the traditional Nobel banquet at Stockholm City Hall.