The goulden twig

Analogies seem to be a teaching necessity; learning something new that has no connection whatever with earlier experience is very, very difficult, and "Proceeding from the known to the unknown" is an almost universally accepted teaching technique. Even the fact that our imaginations have great difficulty in merging the wavelike and particlelike aspects of light has not, as far as I know, inspired any physics teacher to try to bypass both analogies entirely. (Observational selection may be operating here, of course; efforts simply may not have succeeded, so I never heard of them.)

At primary, secondary, and popular teaching levels, where the customer is likely to be unfamiliar with much mathematical symbology, we have to fall back on verbal and pictorial analogies. One of my favorites of these is used often by Stephen Jay Gould in his efforts to point out that evolution is not a simple tree trunk leading from "lower" to "higher" life forms. He pictures a bush, and employs various verbal techniques to convey the complexity and randomness of its branching, the essentially endless variety of directions the growth may take, and lack of preference for any particular one of these - that is, the absence of an upward-thrusting trunk.

I like to apply the same evolution analogy to the growth of human knowledge. It applies nicely to my personal interest, science. I may be grazing one of Dr. Gould's analogy limitations when I do this, because there does seem to be a direction of sorts to the knowledge growth - toward greater probability of correctness - but maybe this is an illusion and, like life varieties, we are merely expanding in all available directions.

I tend to concentrate on the individual twig. It follows a process of growth, starting with a bud of speculation. This grows to the length of a hypothesis, where testing of the increasingly detailed idea becomes possible. If it doesn't get nibbled off by a dinosaur (in other words, fail is testing) it reaches the status of a theory ("only"' a theory, as the creationists put it) and becomes a real branch. The analogy does not extend to the idealistic level of representing a completely established fact, of course. This is all right; real life seldom does this either. It is conceivable, after all, that the earth is a cube embedded in a set of force fields which so alter gravitational, electric, and magnetic lines of force and the paths of electromagnetic waves and momentum vectors that we are deceived into thinking the planet nearly spherical (you could probably find someone who would regard this suggestion as sheer inspiration; please don't blame me for someone's misuse of an illustrative example).

In the bush analogy, my self-supporting hobby of science fiction plays a demonstrable part in the development of human ideas. It operates at the base of the branch, at the speculative start and a little way - sometimes quite a respectable way - out into the hypothesis sections.

There are speculations about parallel worlds, personality transposition, and life in the sun that, at least until recently, no one would have wanted to publish in any other form and for which no suggestions for testing have been offered. There are hypotheses, quite testable, on why crater-lets on the floor of Plato (a 100-km-wide crater on the moon) are sometimes visible through a given telescope and sometimes not, under what seem to be identical viewing conditions. I suggested one, involving magnetic focusing of solar particles, some decades ago in The Strolling Astronomer, organ of the Association of Lunar and Planetary Observers. It produced a resounding silence among professional astronomers. However, I based a science fiction story, "Dust Rag," on the same idea a few years later; it sold readily, has been anthologized more than once since, and I have been told of its use in secondary school science classes. As far as I know, there has been no attempt to check the hypothesis directly, but the moon's more recently established lack of a significant magnetic field does make it unlikely. I can live with this.

Science fiction about space travel, sometimes with much detail about propulsion systems and orbit mechanics, by people like Willy Ley and Robert Heinlein, are far enough along the branch to let one hold on and climb. I invented for science fiction purposes in 1960 anastronomical body I called a "Superjovian." It has since become quite respectable under the name of "brown dwarf." (Discovery of the first brown dwarf, an object known as Gliese 229 B, has recently been confirmed by astronomers.)

I would say not to worry about the limits of this or any other analogy. It's better to have fun with the intellectual ecology to be found in and around the bush.

Hal Clement (Harry Clement Stubbs) is one the most scientifically oriented science fiction writers. His first story, "Proof," appeared in the June 1942 Astounding Science Fiction (now Analog) magazine, and his first novel, Needle was serialized there in 1949. His best-known story (unfortunately, he feels), "Mission of Gravity," appeared in 1953. Other novels are Iceworld, Close to Critical, Star Light, Still River, and Fossil. He was a B-24 pilot in World War II and later a technical instructor, retiring as a full colonel in 1976. He has a B.S. in astronomy and an M.S. in chemistry and taught high school science for forty years.

COPYRIGHT 1996 Committee for the Scientific Investigation of Claims of the Paranormal
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