Sir Arthur Clarke is an Englishman, now in his early eighties, who since the 1950s has lived in Sri Lanka but exercised a worldwide influence. To the general public he is probably best known as the scriptwriter and technical consultant on the Stanley Kubrick movie, "2001: A Space Odyssey." To people in the communications industry, he is most famous as the father of the communications satellite, the concept for which he published back in 1945, before there were satellites of any kind.

To me, he is a writer whose fact and fiction had a formative influence on my own interests and career choice. Today I want to concentrate on one of "Clarke's Laws." This one states: "Any sufficiently advanced technology is indistinguishable from magic."

It is easy to point to devices and discoveries now in common use that endow the average citizen with powers that 500 years ago would have invited a visit from the Inquisition. I will list just 20: telescopes, microscopes, computers, thermometers, wrist watches, antibiotics, anesthetics, CAT scanners, pacemakers, CD players, VCR's, televisions, radios, toasters, microwave ovens, automobiles, aircraft, telephones, fax machines, and X-ray machines.

Almost all the items listed employ electronics, a field that did not exist a century ago. The electron itself, a "subatomic" particle in a world which previously had defined atoms as the smallest possible building blocks of nature, was discovered only in 1897. If we want to find sources of future magic, it is reasonable to ask whether there is there some other fundamental subatomic particle whose properties we have so far not exploited?

There is. There exists an esoteric and mystifying particle, the neutrino, with properties that seem almost supernatural. Its existence was proposed back in 1931, by Wolfgang Pauli, simply as something that was needed if the balance of energy and spin was to be preserved in certain nuclear reactions. The next 20 years provided a measure of the neutrino's elusive nature. In spite of the best efforts of physicists, no neutrino was observed experimentally until 1953. Today, almost 50 years later, we have been able to find no practical uses for the neutrino. Worse than that, we remain ignorant of at least one of its basic properties.

The fundamental particles from which matter is constructed possess some combination of three things: mass (for our purposes, this is the same as weight), electric charge, and spin. Protons, electrons, and quarks have all three; neutrons have mass and spin, but no charge. The class of particles known as bosons sometimes have mass and sometimes have spin. The neutrino has no charge. It definitely has a spin. And the jury is still out, after 50 years of experiments, on whether or not the neutrino has mass. If it does, that mass must be very small compared with even the "light" particles such as the electron.

Part of the reason why it is so hard to get a handle on the neutrino is that it interacts scarcely at all with other matter. Billions of neutrinos a second pass through your body as if you didn't exist. Very rarely, a neutrino will encounter the nucleus of an atom, inducing some kind of change and itself being swallowed up in the process. To stop that neutrino getting through to you, you would need a lead shield light-years thick. Fortunately, the occasional neutrino that does interact with matter does you no measurable damage.

To make life a little more complicated, there seems to be not one type of neutrino, but three. They appear able to change into each other, in ways that we still do not understand. Unless such a change is occurring, neutrinos refuse to obey the laws of arithmetic. We can calculate how many neutrinos per second the Sun must produce during the ongoing hydrogen-to-helium conversion that provides enough energy to keep it shining. When we perform an experiment to count those neutrinos, we find only one-third as many as expected.

The neutrino certainly qualifies as a suitable instrument for future technology. Its use would look to us like magic, though given our current degree of ignorance it is hard to offer many predictions as to what that magic might be. I know of only two suggestions that would make use of neutrinos. Both of them would exploit the extraordinary degree to which neutrinos penetrate ordinary matter. The first is in communications with submarines. This is a notoriously difficult problem since radio signals at normal frequencies do not pass through water. A beam of neutrinos, modulated in their numbers so as to provide a signal, will easily travel any distance through the ocean. The big problem lies in capturing enough of them to read the signal. No one has ever done this. I should add the disclaimer, "to my knowledge," since the Defense Department was interested. But I believe that we have no working neutrino transmitters and receivers.

The second application is for exploring deep within the Earth. A device known as a Geotron was proposed in the 1970s as a method of imaging the interior of the whole planet. It can be thought of as a giant CAT scanner, employing neutrinos rather than X-rays. Tight beams of high-energy neutrinos are sent in all directions and pass through the middle of the Earth, scattering off structures in the interior and emerging at points around the world where their numbers are measured. A set of computer programs takes the information on the detected neutrinos and uses it to deduce the planetary interior structures encountered in traveling from the Geotron to the detection chambers.

The neutrino production unit of the Geotron would have been quite a structure, a ring more than 40 kilometers across. Although the proposers had first-rate scientific credentials (they included the first director of Fermilab), the Geotron never got beyond the drawing board.

Two negative examples prove very little, except maybe our state of ignorance. Today we know less about the neutrino than we knew about the electron in 1910. In that case, the road from discovery to universal application was a long one. It is likely to be at least as long before we see practical uses for the neutrino.

It may also be that the neutrino will play no great role in future technology. Some other peculiar particle - say, the muon or the neutral pion or the Higgs boson - may turn out to be the important one. In fact, you might almost say it has to be that way. For if the path ahead were easy to see, that would disqualify it as the road to future magic.

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