Nobel Prize in physics awarded to Francis Halzen for his work detecting ‘ghostly’ cosmic particles

By Issy Ronald, Katie Hunt, CNN

(CNN) — The 2026 Nobel Prize in physics has been awarded to Francis Halzen, a pioneering Belgian astrophysicist whose work developing a massive observatory in Antarctica to detect “ghostly” cosmic particles laid the foundations for an “entirely new type of astronomy.”

These tiny, high-energy particles from space, known as neutrinos, transmit information which allow scientists to better understand distant galaxies and exploding stars, said Nobel committee member Eva Olsson at the award presentation on Tuesday at the Royal Swedish Academy of Sciences in Stockholm.

“Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument,” said Nobel committee chair Mark Pearce in a statement. “His tenacity and scientific vision has paved the way for a new kind of astronomy.”

Halzen, 82, told the Nobel news conference by phone from Italy that it was a “great surprise” and “pleasure” to win the award.

“When we started this project, everybody realized this was maybe a good idea but very few thought it would work, including myself,” he said. “So this was kind of an adventure where success wasn’t guaranteed.”

The professor, who is based at the University of Wisconsin–Madison, first presented plans for the IceCube Neutrino Observatory in 1988, envisioning a vast network of sensors in Antarctic ice that could capture neutrinos.

The observatory harnesses a key property of neutrinos — that they produce a flash of light when colliding with an atomic nucleus which could be tracked by sensors embedded in clear, glacial ice.

Arriving at Earth from the far reaches of the cosmos, neutrinos are often called “ghostly” because they are extremely volatile, or vaporous, and can go through any kind of matter without changing. They have almost no mass, and no electrical charge. They can travel through the most extreme environments, like stars, planets and entire galaxies, and remain the same.

“It’s been a while since the Nobel Prize has gone to a single individual and that points to the uniqueness of his vision,” said Richard Fitzgerald, editor-in-chief of Physics Today, which is published by the American Institute of Physics. “It took a team of hundreds of people to build it, but it all started with one person.”

Observatory in the ice

While billions of neutrinos originate from the sun, neutrinos that come from other regions of space are much rarer and harder to detect.

In the 1980s, Halzen first realized that Antarctic ice could be ideal for trapping these secretive neutrinos but installing sensitive equipment deep in the ice was a huge endeavor requiring researchers to drill kilometer-deep holes and lower strings of light sensors.

IceCube’s predecessor, known as AMANDA, was completed in 2000 but it didn’t manage to detect the high-energy neutrinos Halzen was looking for, the Nobel Committee said. Work then began on IceCube – a cubic kilometre of ice equipped with light sensors, which reached its full size in 2011, with 5,160 light sensors divided between 86 cables.

In 2013, the research team reported the first evidence to support the detection of cosmic neutrinos and a couple of years later, they had gathered enough data to be certain of their discovery.

The Nobel committee said IceCube would take neutrino astronomy to a new level, providing information about cosmic phenomena that are hidden behind dust clouds and distant space objects such as black holes.

A project to expand IceCube, allowing it to monitor eight cubic kilometers of ice, is planned.

Last year, the physics prize went to John Clarke, Michel Devoret and John Martinis for their discovery of a phenomenon called quantum mechanical tunneling in an electrical circuit, an advance that laid the foundation for quantum computing and other related technology.

The prize carries a cash award of 12 million Swedish kronor ($1.2 million). On Monday, the Nobel Prize in medicine was awarded to three scientists for their work developing a technique to decode the inner workings of the brain.

The awards continue on Wednesday with the announcement of the chemistry prize, followed by literature on Thursday. The peace prize will be revealed on Friday, followed by the Nobel Memorial Prize in Economic Sciences on October 12.

This story and its headline has been updated with additional reporting.

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CNN’s Ashley Strickland contributed reporting.