The 2026 Nobel Prize in Physics went to Francis Halzen for IceCube, a telescope buried in Antarctic ice. Here is how this remarkable instrument works.

A neutrino is a ghost-like particle with almost no mass and no electric charge. Trillions pass through your body every second without you noticing. They barely interact with matter at all.

That makes them hard to catch but extremely useful. Unlike light, neutrinos travel in straight lines from their source. They can point back to black holes and other violent cosmic events hidden behind dust clouds.

Halzen's idea, first proposed in 1988, was to use a cubic kilometre of clear Antarctic ice as the detector. Researchers drilled deep holes and lowered 5,160 light sensors on 86 cables into the ice.

When a rare neutrino collides with an atom in the ice, it produces a faint flash of light. The sensors record these flashes, and scientists calculate where the particle came from.

The observatory was completed in 2011. In 2013, IceCube confirmed the first high-energy neutrinos from outside the solar system, opening a new way to study the cosmos.