Your body contains about 20 milligrams of potassium-40 which is beta radioactive. In other words your body emits about 340 million neutrinos per day and you never notice it. Furthermore, daily millions of neutrinos from the sun pass through your body because neutrinos being massless can pass through anything just like X-rays and gamma rays. Don't worry they can never harm you. But then what are neutrinos?.
Neutrino was proposed by the physicist extraordinaire Wolfgang Pauli in 1930 to explain the continuous spectrum of Beta decay. Pauli set the pace to what is now one of the most active areas in physics in his famous "Dear Radioactive Ladies and Gentlemen..." telegram to a physics seminar. In those day introducing a new particle was like a heinous crime and many physicists viewed Pauli's hypothesis sceptically. One of the physicist who took Pauli's suggestions seriously was the great Italian physicist Enrico Fermi. He used the hypothesis to mathematically formulate the beta spectrum in 1933. Thus was born the Fermi golden rule which in principle enabled the creation of the atomic and nuclear bombs. Fermi used to say that once he understood quantum electrodynamics he knew how to write the beta decay interaction.
The trail of Nobel Prize winners in the area of neutrino physics also explain why it is such a thriving industry. Consider these cases:
In 1953 Cowan and Reines set about to observe neutrino interactions and in 1956 Reines sent a telegram to Pauli to tell him that neutrinos indeed exist!. Reines recieved the Nobel Prize in 1995 for the pioneering neutrino experiment(Cowan was deceased by that time).
In 1962 Lederman, Schwarts and Steinberger set an experiment to check whether there were a family of neutrinos. Nowadsy we know that there are three flavours of neutrino. In 1988 Lederman, Schwarts and Steinberger recieved the Nobel Prize "for the neutrino beam method".
In 1975 Martin Perl and company discovered a new family of lepton, the tau lepton. In 1995 Perl recieved the Nobel Prize 'for the discovery of the tau lepton'.
In 1962 Davis installed 600 tons of carbon tetrachloride in the homestake goldmine in South Dakota USA. The aim was to collect and detect the argon atoms from a reaction first suggested by Bruno Pontecorvo in 1946. This was to measure the flux of solar neutrinos(ie neutrinos from the sun). Davis won the 2002 Nobel Prize in Physics for his work on solar neutrinos.
No other particle has generated such excitement in physics and drawn a rare sort of breeds of the very best brain in quest to understand nature better. For close to seventy years now some of the finest brains the world has ever seen have appended their signature to the study of neutrino mystery: Feynman, Pauli, Dirac, Fermi, John Bahcall(presently at IAS-Princeton University) among others. Major universities like Oxford, Cambridge, Harnvard, Yale, Kyoto, Stanford, Caltech, Princeton, Cornell to name but a few have made sigbnificant investment in the study of neutrinos. Major collaborating institutions include CERN, Fermilab and would you believe it? NASA!.
John Updike, apparently bored with a lecture in Harvard University in 1963, immortalised neutrino in a poem:
Neutrinos, they are small
They have no charge and have no mass
And do not interact at all
The earth just a ball....they simply pass.
They......ignore.....steel
...................................
.......infiltrate you and me.
....At night they....pierce the lover and his lass.
The attempts to have a complete picture of what physicists call the the standard model can only be complete if the current burning issue of neutrino oscillations is resolved. Infact if neutrino oscillations is confirmed then the standard model would be thrown into disarray. There is also the concept of neutrinoless double beta decay that if confimed would demolish the now reverred law of lepton number conservation. Facts: The experimental observation in 1957 that only left handed neutrinos and right handed antineutrinos existed in nature shattered the once invisible law of parity conservation. It is a common knowledge nowadays that nature is a little left handed. Pauli once remarked that "Perhaps God is a little left handed".
Finally, neutrino is so precious that literally billions of dollars are yearly pumped into projects related to studies of this tiny particle. By the way neutrino cannot be observed by even the finest microscope and in principle nobody has ever observed a neutrino. It can only be inferred from the recoiling nucleus in various reaction. The are currently three families of neutrinos the muon, tau and electron neutrinos. It is believed that these flavours of neutrino can switch from one flavour to another, hence neutrino oscillation. This might help to explain why the solar neutrino flux is less than expected.
Watch out for more!!!!!!!!!!!!!!!!!!!!!!
