The Nobel Prize in Physics 2015 was awarded jointly to Takaaki Kajita and Arthur B. McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass"
Neutrino means ”small neutral one” in Italian.
The scientists led two sophisticated experiments that found that the elusive particles can morph from one variety into another(neutrinos change identities) — a phenomenon that can occur only if neutrinos have mass. The discovery delivered a jolt to particle physics because prevailing theories had predicted that neutrinos were massless.The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe
Physicists knew there are three types of neutrinos: muon, electron and tau. But in 1998, Kajita and his team at the Super-Kamiokande experiment found evidence that neutrinos produced in Earth’s atmosphere switched identities before striking the detector, located under a Japanese mountain. Three years later, McDonald’s Sudbury Neutrino Observatory collaboration discovered that some neutrinos emitted by the sun change flavors en route to Earth.
Today physicists around the world are working to identify the particles’ exact masses and understand neutrinos’ importance throughout the history of the universe.
Neutrinos are the second most abundant subatomic particles in the universe, after photons, which carry light. Their existence was predicted in 1930, but for decades, they remained some of the most enigmatic elements of astrophysics.
A neutrino isThe scientists showed that neutrinos, which are found in three “flavors,” could oscillate from one flavor to another, demonstrating that they do not lack mass.
The universe is swamped in neutrinos that are left over from the Big Bang, and many more are created in nuclear reactions on earth and in the thermonuclear reactions that power the sun.
Once thought to be massless and to travel at the speed of light, they drift through the earth and our own bodies like moonlight through a window. Knowing that they can change identities means that they have mass, and that has helped cosmologists understand how the universe has evolved and how the sun works and perhaps will help them improve their attempts to create fusion reactors on earth. "an elementary particle which holds no electrical charge, travels at nearly the speed of light, and passes through ordinary matter with virtually no interaction," according to the physics.about.com website.
Scientists operating huge underground detectors in Japan and Canada are racing to obtain independent proofs that the elusive neutrino, a ghostly particle whose vast family may constitute a large part of the mass of the universe, changes form as it flies through matter or space.
At least some neutrinos are now believed to have some mass, and physicists would love to learn how much, a goal that may be reached by studying the changes in form a traveling neutrino undergoes.
At issue is the effect of neutrinos, which pervade every cubic inch of the universe, on the rate at which the universe expands. Physicists also hope that further neutrino discoveries will account for the Sun's ''missing neutrinos,'' neutrinos predicted by theory but not yet detected by observation.
Scientists say that neutrinos, because they interact weakly with other particles, can probe environments that other kinds of energy, such as light or radio waves, cannot penetrate.
The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.
The discovery rewarded with this year’s Nobel Prize in Physics have yielded crucial insights into the all but hidden world of neutrinos. After photons, the particles of light, neutrinos are the most numerous in the entire cosmos. The Earth is constantly bombarded by them.Neutrinos are essential to the nuclear reactions that change protons to neutrons and vice versa, they influence which elements form in what relative proportions.
The chameleons of space
Physicists later discovered that neutrinos come in three types, whimsically called flavors. The flavor seen first was the electron neutrino, which interacts only with electrons. Heavier electron like particles known as muons and tau particles are accompanied by their own flavors of neutrinos.
Neutrinos are essential to the nuclear reactions that change protons to neutrons and vice versa, they influence which elements form in what relative proportions.Neutrinos play a role in the mysterious dark energy that is pushing the universe apart or that neutrinos could be used for interstellar communication.
Ref--
http://www.nytimes.com/2015/10/07/science/nobel-prize-physics
http://www.cbc.ca/news/technology http://goo.gl/kuV8je
http://edition.cnn.com/2015
https://www.sciencenews.org
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