When It All Goes South

Johan Jarnestad/The Royal Swedish Academy of Sciences Stylized illustration of a neutrino hitting a block of ice. This year’s Nobel Prize in Physics was awarded to Francis Halzen for “decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.” This is the fifth time the Nobel Prize was awarded for work on neutrinos. In 1988 it was awarded for the discovery of the muon neutrino, in 1995 for the detection of neutrinos, in 2002 for detecting cosmic neutrinos, and in 2015 for neutrino oscillations. So why give yet another award for neutrino research? It’s because neutrinos are persnickety. Unlike protons and electrons, neutrinos have no electrical charge. You can make neutrinos by slamming together particles in an accelerator, but they don’t show up in your scintillators. Neutrons are also chargeless, but they have about the same mass as a proton and have the good sense to decay into charged particles we can easily…