Thursday, December 29, 2005

A Triumph of Conservation laws - The Neutrino Nobels by Nat Kannan IITM 1970

A Triumph of Conservation laws - The Neutrino Nobels
by Nat Kannan IITM 1970


Friends,

One of the profoundest of natural laws I learned at IIT was the Laws of onservation - of energy, mass( and both together), momentum, angular momentum, and charge. Of course there are anti particles to match these so that we can construct a symmetrical
anti-universe. To this day I am amazed by this as I ponder why these things have to be conserved at all. Nevertheless, it is a testament to human mind that can abstract something so amazing about the universe.

Conservation laws have lead to discovery of just about all the 12 fundamental particles known to date - six quarks, electron, muon, tau, and neutrinos associated with each of the last three. Enrico Fermi posited some seventy odd years ago the existence of Neutrinos ( the little neutral ones in Italian) as a way to meet
the requirements of conservation laws to explain the missing mass in certain nuclear decays. Since then they have found three possible neutrinos and today there were three Nobel Prize winners in Physics two of which for helping prove that they exist and that they have a non-zero mass and that there are three and only three types.
The other Nobel went for devising ways to discover of cosmic X-ray sources, which was another astrophysical mystery. Now we have X-ray detectors in outer space collecting a view of the universe not known before, which makes it possible to infer the other elusive object in outer space, the Black Holes.

If someone told you that there is a particle you can't see and you can't attract or repel with an electromagnet and it weighs 10,000 times less than an electron and tell you to believe it then you will tell call him crazy. But that is how the Neutrino research was for most of the past six decades. Neutrinos just pass through
everything at close to the speed of light. They can observe its presence only indirectly. The fusion reaction at the core of Sun where Hydrogen gets fused into Helium creates a stream of Solar neutrinos that go through our bodies every second in trillions and trillions into to the earth. These particles are so elusive
that the first project in mid 1950s to detect them was called Project Poltergeist. The scientists had to create underground tanks that were far from other radiation with special chemicals to capture the tracks made by these elusive rascals.

This had been a holy grail for a long time. The measurement problem was so monumental that one got used to disappointments year after year. Finally during the 1990s lot of good breaks came for these scientists who shared the Nobel. Raymond Davis Jr., 87, of the University of Pennsylvania shares half of the Nobel prize with
Japanese scientist Masatoshi Koshiba, 76, of the University of Tokyo. The two men pioneered the construction of giant underground chambers to detect solar neutrinos.

Riccardo Giacconi, 71, of the Associated Universities Inc. in Washington, D.C., won the other half for helping the discovery of cosmic X-ray sources.

Now we are one more step closer to understanding the mysteries of the Universe, thanks to these amazing and persistent minds.

KK