The 2026 Nobel Prize in Physics has been awarded to Francis Halzen, the scientist whose idea turned a cubic kilometre of Antarctic ice into a telescope for some of the most elusive particles in the universe.
The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics 2026 to Francis Halzen of the University of Wisconsin–Madison in the United States.
The prize, announced on October 6, was given “for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin”.
Particles That Pass Through Everything
Neutrinos are everywhere, the Academy explained, but they do not make themselves known. They pass all the way through the Earth, and through our bodies, without being noticed.
Very rarely, a single neutrino interacts with an atomic nucleus. That is what makes it possible, with the right equipment, to detect them.
Their elusiveness is also what makes them valuable. Scientists have long known that the cosmos contains natural particle accelerators, firing out particles with energies up to a million times greater than can be achieved in laboratories on Earth. Unlike other particles, neutrinos reach us without changing direction or losing energy, so they can carry information that is not available in any other way.
An Idea From 1988
Halzen first presented his vision for capturing neutrinos at the South Pole in 1988.
When a neutrino collides with an atomic nucleus, it produces a flash of light. In clear glacial ice, that light can be tracked by sensors. The Academy noted that the South Pole’s ice is free from various kinds of interference and that the area is geologically stable, with no earthquakes.
The idea soon gained the support of other researchers, and within a few years preliminary tests of sensors in the ice were under way.
A Cubic Kilometre of Ice
Cosmic neutrinos with extremely high energies are very rare, so an enormous volume of ice is needed to observe enough collisions.
The result was IceCube, which covers an entire cubic kilometre of ice equipped with light sensors. It was finished in 2011.
Researchers soon detected the first high-energy neutrinos and, a few years later, published their discovery of neutrinos that must originate far outside our solar system.
‘A New Kind of Astronomy’
“Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument,” said Mark Pearce, chair of the Nobel Committee for Physics. “His tenacity and scientific vision has paved the way for a new kind of astronomy.”
The Academy said the neutrino interactions continuously collected by IceCube will give researchers new knowledge about the violent settings in which high-energy neutrinos are created, and could even reveal previously unknown cosmic phenomena.
The Laureate
Halzen was born in 1944 in Tienen, Belgium, and received his PhD in 1969 from KU Leuven. He is a professor at the University of Wisconsin–Madison.
The prize amount is 12 million Swedish kronor.
Image: The IceCube Laboratory at the South Pole, 2023. Photo by Christopher Michel via Wikimedia Commons, CC BY-SA 4.0.