'Ghost particles' from space telescope wins physics Nobel

Belgian physicist Prof Francis Halzen has won the Nobel Prize in Physics for his pioneering work on an observatory that detects particles from space, shedding light on the distant universe.

Halzen led the development of IceCube at the South Pole, which uses a cubic kilometre of Antarctic ice fitted with light sensors to detect particles called neutrinos. These carry information about violent, high-energy processes in the cosmos.

The Royal Swedish Academy of Sciences said "his vision and scientific leadership have been fundamental for the IceCube Neutrino Observatory".

Halzen first presented his vision for detecting neutrinos at the South Pole in 1988.

"Francis Halzen has led an international team of researchers and engineers who have provided us with a fantastic instrument," said Mark Pearce, Chair of the Nobel Committee for Physics.

Neutrinos are elusive subatomic particles. The Sun produces vast numbers of them: every second, billions pass harmlessly through an area the size of your fingernail.

But IceCube is searching for much higher-energy neutrinos, those produced by violent processes far beyond our Solar System — in distant galaxies.

Neutrinos can be thought of as astronomical messengers that point to those fundamental events.

At the observatory, most neutrinos pass straight through the ice, but occasionally one interacts with it, producing particles that give off a telltale flash of light.

These rare signals carry clues to where the neutrinos came from and the extreme conditions that produced them — allowing scientists to investigate places that ordinary telescopes cannot easily see.