I’ve been busy lately with work and getting ready for our trip, so I’ve neglected to keep up with what my Tivo is recording. Well, I finally decided to sit down and watch a Nova episode and it was fascinating. It’s an old show from 2006 that they had replayed, but I’d never seen it before. It was about the search for the neutrino.
It started back in the 1930′s when radioactive decay was being studied and they realized that some of the energy was missing. Based on the law of conservation of energy, the amount of energy at the beginning of a reaction should be the same as that at the end. But in the case of radioactive decay, a small amount was missing at the end. So Wolfgang Pauli postulated that there must be some other bit of pure energy produced in the reaction and he called it a neutrino. This meant that the particle must be massless and therefore travel at the speed of light. Since it had no charge, it didn’t interact with things making it very difficult to detect. And as such, no one even tried for many years. Well, this was the sad state of affairs until the late 1950′s when a couple of physicists working on a nuclear reactor proved the neutrino exists. That lead to the 1960′s when a theoretical physicist by the name of John Bahcall took that bit of information about the neutrino and calculated how many neutrinos the sun would produce. It turns out to be alot. One way to envision it is to realize that roughly 50 trillion neutrinos pass through your body every second.
Well, with that, Ray Davis decided he had to devise a way to test this hypothesis and the calculation, so off to work he goes. To test this, he basically went into an abandoned mine deep under the earth and filled a large vat with a cleaning fluid which is mostly chlorine. The thought was a few neutrinos would strike the fluid and cause bits of it to decay to argon. This was supposed to happen about 10 times in a week, so out of all this fluid they would sift through and try to count the quantity of the argon atoms and see if the counts matched their expectation.
That alone sounds like a feat unto itself, but what they found was the number didn’t match to the calculated value. They only found about one third of what they expected. So the empirical data didn’t match the hypothesis. The two scientists went back and forth trying to figure out who was at fault. Well, it turns out neither of them were. To make a long story short, the initial assumption was that neutrinos were massless, but it was determined that they had a very small mass and this helped to explain quite a bit and set things right.
The side benefit was that this also might explain the disparity in the universe between normal matter and anti-matter. That is, why is there so much more normal matter than anti-matter. Well, they think the neutrino might be the reason.
What was fascinating to me about this was the dedication of these two scientists to the work they were doing, not knowing whether their work would ever amount to anything. They basically spent about 40 years of their lives on this endeavor and most of it having to defend their calculations and experiments. Now that’s dedication.
The other fascinating thing to me is that this is a classic example of science in action. Someone postulated the existence of the neutrino, another scientist took that information and came up with a testable hypothesis and another scientist worked to test the hypothesis. And when they found the results didn’t match, they went on to try to understand why and in so doing uncovered something that may explain one of the great unanswered questions about the universe.
Now if that isn’t awe inspiring, I don’t know what is. As you can probably tell, this show had an effect on me. These are the people who should be held in high regard in our society. These people work in obscurity to further the understanding of mankind, without the thought of fame or fortune. Very few scientists ever become household names, but their contributions to our understanding are incalculable.
