Neutrino physicist wins 2026 Nobel Physics Prize

Cosmic signals

In 2014, IceCube discovered three neutrinos with unprecedented high energies, nicknamed Bert, Ernie, and Big Bird. In 2017, physicists traced a high-energy neutrino back to a specific source—a distant galaxy, called TXS 0506+056, often referred to as “the Texas event.” That same year, IceCube scientists tested a Standard Model prediction: that neutrinos are more likely to interact with matter at higher energies. As predicted, the number of neutrinos arriving through the Earth dropped compared to the ones coming in tangentially, and their frequency dropped further as a product of energy.

And in 2022, IceCube scientists backtracked the paths that high-energy cosmic neutrinos traveled on their way to Earth. After poring over ten years of data, they found evidence—in the form of a tantalizing excess of 79 neutrinos—that an active galaxy called Messier 77 (aka the Squid Galaxy) is a strong candidate for a high-energy neutrino emitter. This result brought astrophysicists one step closer to resolving the mystery of the origin of high-energy cosmic rays.

“Cosmic rays, wherever they are born, make neutrinos, but at the time, we had no idea where or how,” said Halzen. “Now, by seeing neutrinos, we start to see the first cosmic accelerators, and that’s really exciting.”

IceCube isn’t done making new discoveries. “We have these neutrinos of enormous energies, but all the physics that we are doing seems to be consistent with the Standard Model neutrino physics that we know and love, and we want to break that,” Halzen said.

The project just completed a major upgrade in February, adding five more strings of light sensors to the bottom center of the existing arrays, along with an additional 600 new light sensors and calibration instruments. Last month, the National Science Foundation committed $53 million over the next five years to maintain operations.

As for Halzen’s future research plans, “I am working on a proposal, and I hope that this prize will help getting it approved,” he joked during the news conference.