We’ll be delving into the strange and fascinating world of astronomy lingo in this series! Today’s theme, neutrinos, will be barely visible!
The neutrino is one of the most vexing types of particles known to science. The neutrino was initially postulated by scientist Wolfgang Pauli to explain why the nuclear beta decay event seemed to break energy and momentum conservation. He reasoned that the additional energy and momentum may be carried away by a small, unseen particle.
Later researchers confirmed the neutrino’s existence, and Enrico Fermi called it after the Italian word meaning “little neutral one.”
Because neutrinos have such a tiny mass, scientists have assumed they are massless and move at the speed of light for decades.
Physicists now know that neutrinos have mass, but they don’t know how much mass they have. The fact that there are three types of neutrinos adds to the complexity of the situation. The electron-neutrino, muon-neutrino, and tau-neutrino are the three types of neutrinos. Each kind of neutrino, or “flavor,” emerges exclusively in reactions involving the corresponding electron flavor (the regular electron, its heavier cousin the muon, and its even heavier cousin the tau).
Things are just going to get worse. Neutrinos, unlike any other particle, have the capacity to change flavor as they move. So an electron-neutrino may be produced in a process, but by the time it reaches a detector, it might be a muon-neutrino or a tau-neutrino.
It just gets worse. Neutrinos barely seldom interact with ordinary matter, only taking part in weak nuclear force reactions. As a result, finding them necessitates the use of very big detectors. The IceCube experiment near the geographic South Pole, for example, searches a whole cubic kilometer of Antarctic ice for neutrinos. They sometimes strike a sliver of water in the ice, creating a flash of blue light that may be detected by detectors drilled into the ice.
One of the most prominent puzzles in contemporary physics is the unknown masses of the three neutrino flavors, as well as the issue of whether more, even more difficult to detect flavors exist. The Standard Model of particle physics provides no explanation for neutrino mass, and many scientists feel that solving the enigma would require a dramatic revision of our knowledge of physics.