IceCube strings 5,160 digital optical modules between 1,450 and 2,450 meters deep, melted in by hot-water drill; the last of 86 strings went in on December 18, 2010, a decade after the proposal. The Royal Swedish Academy cited Halzen for decisive contributions to the observatory and the discovery of high-energy neutrinos of astrophysical origin, with twelve million kronor attached; before him, the last solo physics Nobel went to Georges Charpak in 1992.
The gamble was real: as APS chief Jonathan Bagger noted, nobody knew extragalactic neutrino sources would be bright enough to detect, and Halzen pushed the proposal through peer review anyway. He first presented the South Pole vision in 1988; DUMAND off Hawaii, the concept's predecessor, was terminated in 1995. The field's obituary was half-written when the ice delivered.
The Nobel caps each prize at three recipients, a rule from an era of tabletop physics. IceCube is 450 scientists at 58 institutions; the citation landed on the one name that drove it. Halzen's own first words were for the courageous people who joined at the start. The medal measures vision and stubbornness, not cubic kilometers.
A Nobel for one man, for a machine built by four hundred fifty people across fourteen countries; what exactly does the medal measure?