Francis Halzen received the 2026 Nobel Prize in Physics. The Royal Swedish Academy of Sciences said the award recognised his decisive contributions to the IceCube Neutrino Observatory and the discovery of high‑energy astrophysical neutrinos.

Halzen realised that the South‑Pole ice could be used to track neutrinos. These particles rarely interact with matter, but when they do they create tiny flashes of light that can be recorded by sensors embedded in the ice.

The IceCube Neutrino Observatory is located at the Amundsen–Scott South Pole Station in Antarctica and covers an entire cubic kilometre. The array of light sensors was finally switched on in 2011, fulfilling a vision that started in the late 1980s, according to the academy.

When a neutrino collides with an atomic nucleus in the ice, it produces a brief burst of Cherenkov radiation. The surrounding photomultiplier tubes capture this flash, allowing scientists to reconstruct the neutrino’s direction and energy.

An extension called IceCube‑Gen2 is planned for 2033. It will enlarge the instrumented volume to eight cubic kilometres, roughly eight times the current size, and is expected to detect ten times more neutrinos, including much weaker ones.

Eva Olsson of the Royal Swedish Academy of Sciences explained that these “messenger” particles bring information from distant galaxies and exploding stars, opening a new window on the cosmos.