Neutrinos in the News

Something’s up. Perhaps there’s some degree of hope that we may be reversing the tide of “dumbeddownness” in the stories that the media pumps through its many tubes to reach us. So, it comes as a welcome surprise to see articles about the very, very small making big news in publications like the New Yorker. Stories about neutrinos no less. Thank you New Yorker for dumbing us up. And, kudos to the latest Nobel laureates — Takaaki Kajita and Arthur B. McDonald — for helping us understand just a little bit more about our world.

From the New Yorker:

This week the 2015 Nobel Prize in Physics was awarded jointly to Takaaki Kajita and Arthur B. McDonald for their discovery that elementary particles called neutrinos have mass. This is, remarkably, the fourth Nobel Prize associated with the experimental measurement of neutrinos. One might wonder why we should care so much about these ghostly particles, which barely interact with normal matter.

Even though the existence of neutrinos was predicted in 1930, by Wolfgang Pauli, none were experimentally observed until 1956. That’s because neutrinos almost always pass through matter without stopping. Every second of every day, more than six trillion neutrinos stream through your body, coming directly from the fiery core of the sun—but most of them go right through our bodies, and the Earth, without interacting with the particles out of which those objects are made. In fact, on average, those neutrinos would be able to traverse more than one thousand light-years of lead before interacting with it even once.

The very fact that we can detect these ephemeral particles is a testament to human ingenuity. Because the rules of quantum mechanics are probabilistic, we know that, even though almost all neutrinos will pass right through the Earth, a few will interact with it. A big enough detector can observe such an interaction. The first detector of neutrinos from the sun was built in the nineteen-sixties, deep within a mine in South Dakota. An area of the mine was filled with a hundred thousand gallons of cleaning fluid. On average, one neutrino each day would interact with an atom of chlorine in the fluid, turning it into an atom of argon. Almost unfathomably, the physicist in charge of the detector, Raymond Davis, Jr., figured out how to detect these few atoms of argon, and, four decades later, in 2002, he was awarded the Nobel Prize in Physics for this amazing technical feat.

Because neutrinos interact so weakly, they can travel immense distances. They provide us with a window into places we would never otherwise be able to see. The neutrinos that Davis detected were emitted by nuclear reactions at the very center of the sun, escaping this incredibly dense, hot place only because they so rarely interact with other matter. We have been able to detect neutrinos emerging from the center of an exploding star more than a hundred thousand light-years away.

But neutrinos also allow us to observe the universe at its very smallest scales—far smaller than those that can be probed even at the Large Hadron Collider, in Geneva, which, three years ago, discovered the Higgs boson. It is for this reason that the Nobel Committee decided to award this year’s Nobel Prize for yet another neutrino discovery.

Read the entire story here.

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