Science - An Introduction

[packbat]

I don't expect I'll ever take up technical writing as my vocation, but if I were ever inspired to write a general science textbook, I expect it might open like this.

It is a common experience to the beginning cyclist. Perhaps she has just started off after taking the bike off the stand; perhaps she's downshifted before climbing a hill; perhaps she's merely riding steadily. In any case, suddenly the pedals get loose, spinning without resistance, and the bicycle is rolling to a stop. So, naturally, our rider jumps off and crouches beside her steed to check if the chain has come off the gears.

Remarkably enough, in this everyday experience we see the quintessence of science.

The layperson, not having worked in the field or spent long hours in the laboratory, may have trouble seeing any commonality between the experiments with titanic energies applied to single electrons at CERN or any other lab with a particle accelerator, the questionnaires diligently filled out by generations of first-year psychology students looking for an extra credit grade, the careful analysis of the compounds dripping out of a distillation flask, and the hypothetical character of the anecdote opening the chapter. Nevertheless, in all these cases, we see elements of the perpetual cycle of questioning, theorizing, and observing.

When our imaginary scientist-cyclist first felt the pedals slipping under her feet, she was immediately presented a problem far more interesting than any that her teachers ever assigned - a sudden unfamiliar experience in a realm important to her, one that she thought she understood. In this respect, it is the perfect impetus for our venture into the description of science, for as the late Isaac Asimov is reputed to have said, the most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!', but 'That's funny ...' - a sentiment which in detonation (though perhaps not in emphasis) our cyclist would heartily agree. In a moment, observing the gradual slowing of her bicycle, I expect she will have turned this initial curiosity into an explicit problem statement: "What's the matter with my bike?"

We, comfortably distant from any visceral involvement with our protagonist's difficulties, would well benefit from noting the particularly analytical nature of the question. She does not ask "how do I get home?" or "how do I fix my bike?" - the questions which one of her examiners might have formulated, imagining this scenario for some hypothetical exam. No, however relevant those questions may be, what she has on her mind is more fundamental than any of them. She wants to know what is happening.

But how can she determine what is happening? What does she need to do so she can make a hypothesis, a guess, to explain an event? She must, and does, turn to what she already knows - how bikes work.

Were this a book of philosophy, the author might choose at this point to begin a digression about the nature of knowledge, the problem of induction, and other matters of still greater complexity and depth of abstraction. As our subject is science, however, I shall merely observe that this method is simply good tactics - it is far easier to judge differences from the familiar than to develop a theory from nothing, and theorizing, my second stage in the cycle of science, is what she is beginning to do now. And, unprompted, she is doing it in the manner of every scientist - by starting with the preexisting theory (in this case, of bicycles).

She does not know the bicycle as the full-fledged thing of complexity that an engineer would deal with. However, her tutors were wise enough to instill a basic understanding of the machine, and from this she knows that her mysteriously-loose pedals are (supposed to be, at any rate) connect to the front gears, which in turn drive the chain, which drives the rear gears, which, finally, are hooked to the wheel pushing the road behind her. And with this model flashing through her mind as she turns her bike towards the shoulder, she recalls: don't chains fall off sometimes?

That's a theory, now. Well, not a theory - a guess, really, but supported by a reliable model, so perhaps it earns the name of a hypothesis. (That is a difficulty of science - words tend to acquire quite startlingly exact meanings. Thus, a "hypothesis" becomes a scientific explanation that hasn't a lot of evidence, and a "theory" one which has quite a lot, like Einstein's theory of relativity. Which is why the Ph.D.s cringe at the too-common dismissal, "it's only a theory".) In any case, whatever you call it, our soon-to-be-ex cyclist has come up with an idea of why the pedals aren't moving her bike forward - that the chain is off.

Now, if we were in ancient Greece, we might halt there- after all, we have explained what happened. However, our temporary pedestrian intuitively knows that, however satisfying her reasoning is, it's only worth using if it meets the final test - it must be true. And if it is true, it must predict independent of what it was invented to explain. In other words, it must not only agree with what invented it to explain (that her pedals stopped driving her bike), but with that which had, before it was proposed, nothing to do with the original subject (whether the chain should be seen sitting on the gears). The explanation does more than concoct a reason for the occurrence - it concocts an explanation that connects this occurrence with others.

So, she looks at the chain. The chain which, before she thought it out, she had no reason to doubt was on the gears. The chain which, if she is right, should be off, and if she is wrong, should probably not be. The chain which, when she observes it (stage three!), will either confirm or deny what she has decided.

And, you will realize, both confirmation and disconfirmation are uncertain. Perhaps the chain fell off, but the original flaw was in the gear. Perhaps the chain slipped off, but hooked back on while she rolled to a stop. Often, in a complex problem, or when presented with an especially counterintuitive idea, scientists will demand many independent observations - independent both of the original question to be answered and of each other. ("Are the gears in good shape? Do the front gears turn with the pedals, and the back with the rear wheel?") And the nomenclature reflects these assessments of uncertainty - explanations with little but aesthetics behind them are dismissed as guesses, best left in the sitting room to amuse but do little harm, while those with titanic amounts of solid observation to support them are handed down as solemn truths to students from their first day in class.

Of course, even such explanations will sometimes be subject to a discomfiting overturn, such as occurred with the tremendously successful Newtonian mechanics. That, you know, was dislodged by Einstein's special and general relativity, and the quantum physics he gave such strong support to as he experimented on the photoelectric effect. But those theories could only dislodge Newton's by the strength of the observations they could explain that Newton could not.

And it is these observations, the ones which, knowing the best theories of the day, still seem a little funny, that will raise the questions for the next cycle of science.