What do you do if you want to catch a particle that can pass through an entire planet without stopping? In 1988, Belgian-born physicist Francis Halzen proposed a strange answer: drill into the ice at the South Pole and wait. Almost nobody believed it would work. This week, the Royal Swedish Academy of Sciences awarded him the Nobel Prize in Physics anyway, for proving that it did.

The particles in question are neutrinos, ghostly fragments flung across space by the universe's most violent events — exploding stars, collapsing black holes, cosmic collisions still barely understood. Neutrinos carry no electric charge, so magnetic fields cannot bend their path. They ignore gas, dust, even entire galaxies, travelling in a straight line from wherever they were born. That makes them extraordinary messengers.

It also makes them almost impossible to catch. Halzen's solution, now known as IceCube, buries thousands of light sensors deep in Antarctic ice. On the rare occasion a neutrino does strike an atomic nucleus, it produces a faint blue flash, and from that flash, scientists can work backward to find where the particle began its journey. "I have to emphasise how lucky I was," Halzen told reporters, recalling that even he had doubted his own proposal.