The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics 2026 to Francis Halzen of the University of Wisconsin-Madison, United States, “for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin”, according to a press release from the academy.
Neutrinos are tiny elusive particles that are everywhere but cannot be easily detected as they rarely interact with other particles. They are passing through human bodies and other objects around without them noticing. The interactions of neutrinos with an atomic nucleus can rarely be observed when the neutrinos are of high enough energy and with the right equipment.
The high energy neutrinos can be generated by mysterious natural particle accelerators in the universe which can fire up particles to energies that are up to a million times higher than can be achieved in any laboratory on Earth.
In 1988, Francis Halzen proposed an instrument that could capture these high energy neutrinos can be studied to understand the environment of their origins. This is because neutrinos “unlike other particles, neutrinos reach us without changing direction or losing energy. This means they can provide information that is not available in any other way”, according to the press release.
Halzen’s apparatus is essentially an enormous ice structure with a volume of a cubic kilometre embedded with light sensors at the South Pole. The flashes of light produced by the collisions of neutrinos with atomic nuclei would be clearly visible in the glacial ice. For there to be enough number of collisions for the flashes to be detected the ice structure needs to be huge.
“The South Pole’s ice has many advantages, as it is free from various types of interference and the area is geologically stable, with no earthquakes”, as per the press release. After Halzen’s proposal, his idea known as the IceCube gained approval from other scientists and preliminary testing with sensors in ice began a few years afterwards. IceCube came to fruition in 2011.
Researchers soon discovered the first high energy neutrinos and a few years later were able to publish their research on the discovery of high energy neutrinos that had originated outside the solar system.
“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,” said Mark Pearce, Chair of the Nobel Committee for Physics.
“The neutrino interactions that are continuously collected by IceCube will provide researchers with novel knowledge about the violent settings in which high-energy neutrinos can be created — and could even reveal previously unknown cosmic phenomena”, according to the press release.