The 2026 Nobel Prize in Physics went to Francis Halzen of the University of Wisconsin–Madison. The Nobel committee honored his “decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.”
Neutrinos are tiny, electrically neutral particles that pass through almost everything, including you, without being noticed. That makes them very hard to catch. IceCube does it by using the ice itself: it is built into the Antarctic ice near the South Pole, with 5,160 light sensors buried up to about 2 kilometers down. On the rare occasion a neutrino hits something in the ice, it makes a faint flash of blue light that the sensors can pick up. Halzen first proposed the project in 1988, and it finished construction in 2010. By 2013 it had spotted high-energy neutrinos coming from far outside our solar system.
Why it matters: Light can be blocked or scattered on its way across the universe, but neutrinos travel almost untouched. That gives astronomers a brand new way to study extreme places like black holes and exploding stars. If you want to learn what a black hole is first, see our black holes lesson.