When Juan Carlos Díaz Vélez checked the New York Times, he found out his boss, Francis Halzen, had just won the Nobel Prize in Physics. The reason? Halzen’s groundbreaking work with the IceCube Neutrino Observatory, a network of sensors buried in the Antarctic ice, has revolutionised our understanding of the universe’s tiniest particles.

Neutrinos, those ghostly subatomic particles, are everywhere. They stream through your body as you read this, produced by everything from watermelons to the sun. But the IceCube team is after the big guns: high-energy neutrinos that may come from black holes. These cosmic messengers reveal secrets of the galaxy’s most violent events.

Halzen’s team has detected these elusive particles using an array of 5,160 optical sensors in the South Pole. When a neutrino interacts with ice, it produces a muon, which then emits a flash of light detectable by the sensors. This intricate setup has led to groundbreaking discoveries, including the detection of a high-energy blazar, TXS 0506+056, and the confirmation that cosmic rays do not come from all directions equally.

“It’s like looking for a needle in a haystack,” Díaz Vélez explained, highlighting the challenge of detecting neutrinos. “But the data they generate is invaluable, shedding light on the nature of cosmic rays and the distribution of their sources in the galaxy.”

The project, an international collaboration of 450 people from 58 institutions across 14 countries, has not only advanced our knowledge but also highlighted the importance of international scientific cooperation. For Díaz Vélez, it’s a humbling role in a monumental discovery.