The 2015 Nobel Prize in Physics has gone to two researchers who, each at one end of the globe, have demonstrated in their experiments the oscillations of neutrinos , which implies that these elusive particles have mass. “The discovery has changed our understanding of the inner workings of matter and may be crucial for our view of the Universe,” the committee explains in the official statement from the Swedish Academy of Sciences.
In 1998, the Japanese Takaaki Kajita (University of Tokyo), one of the two winners, revealed that neutrinos coming from the atmosphere changed their identity on their way to the Super-kamionkande, a huge detector located a thousand meters underground. Meanwhile, a team of Canadian researchers led by Arthur B. McDonald (Queen’s University), second recipient, demonstrated that neutrinos from the Sun did not disappear as previously thought, on their way to Earth. Scientists had managed to “catch” these elusive particles, which changed identities when they arrived at the Sudbury Neutrino Observatory, a former nickel mine in Ontario.
In this way, the neutrino puzzle that physicists had fought for decades was solved . And it is that these discoveries implied that these particles, contrary to what was thought, had mass.
Space chameleons
“We live in a world of neutrinos,” explains the Academy in its statement. “Every second, billions of neutrinos pass through our bodies. We cannot see or feel them. Neutrinos rush through space almost at the speed of light and rarely interact with matter. ” These “chameleons from space”, as the committee responsible for awarding the Nobel Prize in Physics has called them, are so elusive that even the very scientist who proposed their existence, Austrian Wolfgang Pauli, doubted it. “I have done a terrible thing,” he explained in a letter written to his physicists in 1930, “I have postulated the existence of a particle that cannot be detected.”
Years later, the Italian Enrico Fermi was able to demonstrate a theory that included those particles proposed by Pauli, which he called neutrinos. In 1956, Clyde Cowan and Frederick Reines proved its existence experimentally: the Poltergeist of physics was, indeed, a real particle.
After the discoveries of the award-winning Kajita and McDonald, many mysteries remain to be solved : What is the mass of neutrinos? Why are they so light? Why are they so different from the other elementary particles? Perhaps, in a few years, a future Nobel Prize in Physics will find the answers.
