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06/30/2010
Running a Red Light and Neutrinos
As the song goes in the play "Kiss Me, Kate", it's too darn hot! (This was written yesterday. As I post this today it's most pleasant and cool.) Actually, I shouldn't complain about the heat. I'm lucky to be alive to experience temperature at any level, having nearly become extinct a couple weeks ago thanks to an errant young driver who ran a red light as I was making a left turn (with a green light) at a T-intersection. When I say "ran a red light", the light had been red and he was going about 35 mph from my left. Fortunately, I spotted him coming and managed to stop (almost literally on a dime) and avoid having him crash into me on the driver's side - my wife nearly hit her head on the windshield in the sudden stop. I would estimate we missed colliding by an inch! This experience put me in a reflective mood about life in general and brought to mind two earlier brushes with death on the road. I've probably mentioned these incidents before but I'll do it again anyway.
One was in 1941 near Red Oak, Iowa. My mother had just learned to drive in time to assist my dad on our journey from Pennsylvania to Denver, Colorado to visit my grandparents. Passing a truck, she got off on the shoulder and was losing control when my dad grabbed the wheel. We spun across the road in front of the truck and hit a guard rail, the hood flying up and the horn stuck blowing loudly. Fortunately, the truck driver, also from Pennsylvania, realized we were in trouble and managed to slow down and stop, avoiding crashing into us. We took a train from Red Oak to Denver and picked up the repaired car on the return trip. My mother never drove again.
The other incident occurred on the island of Maui in Hawaii. Our friend Margaret was driving us across the island on the road to Hana. This road had a reputation of being a rather treacherous road to handle. I didn't think it really lived up to its reputation until we stopped at a scenic overlook. We had barely pulled into the parking lot when we heard a loud crash. A large tree had fallen across the road where we had been only seconds earlier! It was a perfectly clear, calm day with no significant wind - the tree just fell. It would have crushed our small Japanese car and probably killed us all! My wife bought a T-shirt in Hana with a logo saying she had survived the road to Hana - it wasn't idle chatter!
Before my latest brush with eternity, I had decided that I would devote this month's column to neutrinos, spurred by an article titled "Through Neutrino Eyes" by Graciela Geimini, Alexander Kusenko and Thomas Weiler in the May issue of Scientific American. However, I've been distracted by my reflective mood, thinking about past experiences and my origins.
Along origin lines, I recently devoted a column to a very old ancestor or cousin, the 4.4 million-year-old Ardi, whose fossil was found in the Middle Awash area of Ethiopia. Remember that Ardi appears to have upset the whole concept of our having descended from a chimp-like ancestor in that Ardi walked upright but also had opposable toes that would have helped in climbing and walking up in trees. The scientists who spent years putting Ardi's delicate fossilized bones together propose that the last common ancestor that we shared with the chimpanzee was more like us than like a modern day chimp and that it was the chimp that changed to become what we see today. We, on the other hand, developed a straight inline sort of toe and a bigger, smarter brain.
The July issue of National Geographic has a most interesting article about Ardi and the Middle Awash. One of the things that impressed me about the earlier pictures of the Ardi fossil was the size of Ardi's hands. Ardi standing just under 4 feet tall, the hands looked huge. However, the Geographic article has an actual-size picture of a recomposition of the skeletal bones of Ardi's hands and, placing my hand on the photograph, I found that Ardi's hand is almost exactly the same size as my own hand. I don't know why but it just made me feel quite close to that long-ago gal (Ardi was a female).
Another article in the May issue of National Geographic brought to mind how much our life has changed since I was born in 1927. The article, "The 21st Century Grid" by Joel Achenbach, deals with the history and future of our electrical grid, a topic we've also considered in these columns. The article brought back memories of visiting my Aunt Edna and Uncle Charlie at their farm near Princess Anne, Maryland in the 1930s. I remember Uncle Charlie playing the fiddle for us in a room lit by the light from "coal oil" lamps. This was in the 1930s, when the Rural Electrification Administration, formed by FDR in 1935, was promoting the introduction of electricity into the rural areas of the U.S.A. Even today, the electrical grid isn't everywhere. It wasn't too long ago that we visited that same friend Margaret in her home in the San Francisco area and she took us to visit her daughter in an organic farming community in the hill off the coast of California. Their only electrical power was supplied by either solar cells or a generator powered by propane.
One of the items discussed by Achenbach is the future of stored energy. The problem, of course, is that the most promising green sources of energy (notably wind and solar) are not constant but can fade to virtually zero on a cloudy or windless day. Hence the need to store energy for occasions when there's a power failure or when the alternate energy sources are not providing power. The article suggests that lithium-ion batteries in electrical or hybrid vehicles be used to store energy and be plugged in on line for use to either store or supply energy when the car is not in use. In that connection, did you happen to notice that one of the metals mentioned recently in connection with the newly publicized mineral deposits in Afghanistan was lithium. Could lithium replace opium as a prime material for exporting for this troubled and troublesome nation?
Well, let's continue reflecting and finally get back to neutrinos. I've been thinking how much the world of science has changed (or not) since I was born. In 1927 there were 8 planets. Pluto was not yet discovered. By the time I was in school, there were nine planets and now, once again, with the demotion of Pluto, there are only eight. Like the planets, when I was born there were generally considered, at least among the general scientific community, to be a handful or so of "fundamental" particles. Unlike the planets in our solar system, the number of fundamental particles has exploded. Hydrogen was known to consist of a proton and an electron. All other elements, consist of protons, electrons and neutrons.
While writing this column, I was shocked to find that I had forgotten that the neutron wasn't discovered by James Chadwick until 1932. The neutron is a strange particle. It is quite stable when embedded in the nucleus of an atom. Take "heavy" hydrogen, deuterium. It consists of a nucleus containing a proton and a neutron and is quite stable. Take neutrons out of nuclei and, whoops, they become quite unstable, decaying with a half-life of only about a dozen minutes into an electron a proton and a neutrino. Actually, it's an antineutrino (it seems that most fundamental particles have an antimatter version of the same thing).
When I was born, there were no neutrinos. At least nobody had detected one and it wasn't until 1930 that Wolfgang Pauli proposed the existence of the neutrino. Why? For some time physicists had been puzzled by the fact that the energies involved in radioactive decay processes didn't add up. Pauli proposed that the missing energy was to be found in the neutrino, the "little neutral one". And therein lies the rub. Because it carries no charge, the neutrino, not detected until 1956, can go sailing untouched through the earth, through space and through most anything without being affected. There are zillions of neutrinos passing through us all the time and, as for me, I haven't felt a thing.
Well, it's now 80 years since Pauli proposed the existence of the neutrino and things have changed immensely. As we must have talked about in past columns, vast underground detectors have been built and by filtering out other particles coming from space or elsewhere, scientists have been able to detect those extremely rare occasions when a neutrino actually bumps into a particle. The rare collision generates other detectable particles and scientists can trace their paths and energies sufficiently precisely that we can be sure a neutrino has been involved.
Now the going gets rough and here's where I will get off after a brief delving into neutrino terminology. Physicist are a strange bunch in naming things and properties. With neutrinos they have decided that neutrinos come in three "flavors". Now, if you can't even detect a neutrino going through your tongue, how can it possibly have a "flavor"? These "flavors" have something to do with how a neutrino reacts with matter. As if things aren't bad enough, a neutrino not only comes in three flavors but it can also have three different masses. To make matters worse, as a neutrino travels it can change its mix of flavors and masses. It's at this point that I give up.
Suffice to say here that scientists are savvy enough to not only build huge underground detectors to detect and measure the properties of neutrinos but now they are getting so good that they are beginning to use the detectors as neutrino telescopes. What good is a neutrino telescope? Let's take our Sun, for example. With an ordinary telescope all we can see is the light emanating from the surface of the sun, which is nice. We see the sunspots and the corona, etc. With telescopes sensitive to the infrared, ultraviolet, X-rays etc., we can different images of our Sun. But what we can't see is the Sun's interior.
Wait a minute. It's in the interior where all the nuclear reactions are going on that power the Sun. Those reactions generate zillions of neutrinos, most of which blithely go through our star without being affected and many of them are sailing through at this very moment. If we can make a neutrino telescope, we should get a picture of what's going on in the depths of the Sun. Ditto for other stars, supernovae, etc. Well, it seems that scientists are becoming clever enough to not only detect neutrinos but also to measure flavors and masses. Even though the flavor and mass of a neutrino may change repeatedly during flight, by somehow averaging the properties of detected neutrinos, researchers can figure out where the neutrinos came from and how they were generated.
To me, the amazing thing is that these smart guys and gals can measure a neutrino's flavor and mass, then mentally undo whatever happened during its long trip from our Sun or from a distant star or supernova by this kind of averaging the behaviors of a bunch of neutrinos. As I understand it, a given neutrino's flavor and mass are independent of one another and each can change (many times) during flight. Nevertheless, there appear to be certain "signatures" or patterns that can be interpreted to reveal the source of a given batch of the elusive little neutral ones. At least that's how I understand it.
Finally, today is a milestone for me. For more than a decade I have been an adjunct associate professor at the University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School. Well, they've finally realized that I haven't shown my face there for a couple of years or so and I will not be reappointed. Today is the last day I can call myself Professor Bortrum. I must thank Professor Alvin Salkind for providing a home for this Bell Labs retiree for most of the past 20 years. It was a great experience.
On another note, I find that writing about scientific matters in the summer heat is becoming more and more difficult for me. Accordingly, I may devote my time to writing something resembling a memoir, whatever that is. I'll plan to post whatever I have written on or before August 1, hopefully.
Allen F. Bortrum
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