Belgian physicist Francis Halzen has won the 2026 Nobel Prize in Physics for his role in creating the IceCube Neutrino Observatory, a massive South Pole detector that captures elusive high-energy particles from deep space to reveal how the universe evolved.
More than 100 trillion solar and cosmic neutrinos stream through the human body every second, while the Royal Swedish Academy of Sciences announced the award in Stockholm, recognizing the 82-year-old researcher for decisive contributions to the IceCube Neutrino Observatory and his discovery of high-energy neutrinos originating outside our solar system.
Halzen Proposes Using Antarctic Ice to Capture Neutrinos
Neutrinos possess nearly zero mass and carry no electric charge, allowing them to travel straight through planets, stars, and human bodies without altering their path or losing energy. Capturing the rare, high-energy varieties demands an enormous volume of material because an enormous volume of ice is needed to observe an adequate number of collisions.
Back in 1988, Halzen first proposed using the clear ice beneath the South Pole as a vast detection medium. His calculations indicated that building a neutrino collector one cubic kilometer in size would successfully capture roughly one neutrino per day if you built a neutrino collector 1 cubic kilometre in size. That vision materialized into the world’s largest neutrino detector, located at the Amundsen-Scott South Pole Station and the world’s largest neutrino detector. Born in Tienen, Belgium, Halzen earned his master’s degree in physics from KU Leuven in 1966 before completing his doctorate at the institution in 1969. He later relocated to the United States, becoming a US citizen and serving as a professor at the University of Wisconsin–Madison, where he directs the Institute for Elementary Particle Physics.
Building a South Pole Telescope
Constructing the observatory required an international collaboration involving more than 450 people across 58 institutions in 14 countries to make the IceCube Neutrino Observatory a reality. Workers used hot-water drills to melt holes 1.5 miles deep into the Antarctic ice cap, lowering thousands of light sensors known as digital optical modules vertically spaced about 55 feet apart.
When a high-energy neutrino traveling through Earth strikes an atomic nucleus in the ice, it generates secondary particles that emit a flash of blue light through Cherenkov radiation creating what’s known as Cherenkov radiation and emitting blue light. The buried sensor network records these flashes, enabling scientists to calculate the trajectory, energy, and flavor of the original particle we can determine the direction the original neutrino came from, its energy and its type. Some of these captured particles carry more than a million times the energy of the protons found at the Large Hadron Collider located at CERN, the European Organization for Nuclear Research.
“This year’s prize is about ghostly messengers from space.”
Ellen Moons, secretary general of the Royal Swedish Academy of Sciences
Eva Lindroth, a researcher in Stockholm and a member of the Nobel Committee, noted that the observatory has helped scientists understand high-energy particles by providing a direct line of sight from distant phenomena, while fellow committee member Eva Olsson described the incoming particles as information arriving straight from the cosmos. Mark Pearce, chair of the Nobel committee for physics, referred to the subatomic particles during a press conference as ghost-like messengers from the cosmos.
IceCube Milestone Timeline
The journey to developing the IceCube Neutrino Observatory involved overcoming various challenges and skepticism, ultimately leading to major physics discoveries.
- 1988: Francis Halzen proposes utilizing Antarctic ice to construct a deep-ice neutrino telescope.
- 2010: Physical construction of the IceCube detector is completed at the South Pole.
- 2011: The observatory initiates full, uninterrupted operations.
- 2013: Researchers record the first definitive high-energy extraterrestrial neutrinos.
- 2017: The facility helps identify a blazar designated as TXS 0506+056 as the first confirmed single source for a high-energy cosmic neutrino.
- 2023: Scientists detect neutrinos originating from within our own Milky Way galaxy.
Halzen Reacts to Surprise Nobel Prize Announcement
While participating via telephone from Italy during the televised news event, Halzen confessed that the announcement caught him completely unawares while addressing the committee on a call that was broadcast live to reveal the laureate.
“It was a great surprise, and I obviously didn’t expect it. But it’s a great pleasure to hear about this prize.”
Francis Halzen, Nobel laureate in physics
Looking back at the early stages of the endeavor, Halzen pointed out that practically no one believed the unorthodox concept would succeed when this undertaking first kicked off, as people acknowledged the theoretical merit but doubted its practical feasibility. He expressed hope that the recognition would honor the courageous colleagues who joined him at the outset who joined me in the beginning of this project, adding that he is currently working on a new proposal and hopes the prestige of the Nobel Prize will assist in getting it approved I am working on a proposal, and I hope that this prize will help getting it approved.
The formal presentation of the award will take place during a ceremony scheduled for December 10, marking the anniversary of the death of Swedish chemist Alfred Nobel, who established the prizes in his will. Members of the royal families of Sweden and Norway are scheduled to be in attendance for the event.