The Italian Almanac
Italian Science - September 12
Italian scientists on Monday opened a new chapter in modern physics when a burst of sub-atomic particles was sent hurtling from Switzerland to a lab buried under Italy's biggest mountain. The groundbreaking experiment aims to find out more about the mysterious particles, called neutrinos, which have never been observed directly. Neutrinos are invisible and pass through matter without leaving a trace. They could account for the mysterious deficit of matter in the visible universe.
The United States and Japan have been stepping up efforts to prove one of the biggest riddles in particle physics, whether neutrinos have mass. But European scientists at the CERN lab near Geneva and the Gran Sasso lab in Abruzzo may now be able to beat them to the punch. The CERN Neutrino To Gran Sasso (CNGS) experiment provides the best hope, scientists think, for establishing that neutrinos can change 'flavour' - an hypothesis first raised almost 70 years ago by famed Italian physicist Guido Pontecorvo.
Neutrinos come in three 'flavours': electron neutrinos (associated with the electron), muon neutrinos (the muon is a bit bigger than the electron) and tau neutrinos (bigger still). CNGS's neutrino bursts could show muon neutrinos changing into tau neutrinos. If this 'oscillation' is captured by Italy's National Institute of Nuclear Physics (INFN), it would subvert standard physics theories which postulate that neutrinos, since they hardly interact with matter, have no mass.
If neutrinos oscillate then theory dictates that they must have mass. It is probably only a very tiny mass, but there are so many neutrinos around in the universe - almost a billion times as many as there are protons - that they could account for at least as much mass as exists in visible stars.