Antarctic ice opened a new window on cosmic neutrinos

Neutrinos interact with matter only rarely, passing through stars, planets and our bodies. This makes them difficult to detect, but they can reveal extreme processes taking place far beyond Earth.

Francis Halzen proposed using deep ice at the South Pole as part of a gigantic detector. Thousands of IceCube sensors record blue light produced when a neutrino interacts in the ice and creates charged particles; its pattern helps estimate energy and direction.

The IceCube Collaboration reported evidence of high-energy astrophysical neutrinos in 2013. The 2026 Nobel Prize in Physics recognized Halzen’s contributions to the observatory and the discovery of particles from cosmic sources, opening a new way to observe the Universe.

Detecting a neutrino does not automatically identify its source. Events are rare and their direction can be uncertain, so researchers combine multiple detections with observations from telescopes that capture light. IceCube is also being upgraded to measure signals more precisely.

The evidence supports the arrival of high-energy neutrinos from beyond the Solar System, but it does not reveal the source of every event. IceCube’s institutional report lists no individual author and describes the collaboration’s work; the Nobel announcement highlights Halzen’s role.