Jack Steinberger, who shared the 1988 Nobel Prize in Physics for expanding understanding of the ghostly neutrino, a staggeringly ubiquitous subatomic particle, died on Saturday at his home in Geneva. He was 99.
His wife, Cynthia Alff, confirmed the death.
The ancient Greeks proposed that there was one invisible, indivisible unit of matter: the atom. But modern physics has found more than 100 smaller entities lurking within atoms, and observations of their dizzying interactions compose the Standard Model of what is now taken to be the order of the universe.
The neutrino’s existence was first proposed in 1931, to fill holes in a theory about the makeup of the universe, but finding one proved maddeningly difficult. It has no electrical charge, travels at nearly the speed of light and has almost no mass. Each second, trillions of neutrinos pass unimpeded through every human being. Not until 1956 — when ways to smash atoms and examine the debris were developed — was one detected.