When Will The USA Go Metric?
QUESTION: What do these four countries (USA, Yemen, Burma, Brunei) have in common?
ANSWER: They are the only nations on the planet that have failed to adopt the metric system of weights and measures.
THE VALUE OF STANDARDIZATION TO SCIENCE
What if a nurse, rather than carefully measuring a quantity of medicine before administering it to a patient, simply gave the patient an amount that “looked right”? Or what if a pilot, instead of calculating fuel, distance, and other factors carefully before taking off from the runway, merely used a “best estimate”? Obviously, in either case, disastrous results would be likely to follow. Though neither nurses or pilots are considered scientists, both use science in their professions, and those disastrous results serve to highlight the crucial matter of using standardized measurements in science.
Standardized measurements are necessary to [...] any scientist because, in order for an experiment to be useful, it must be possible to duplicate the experiment. If the chemist does not know exactly how much of a certain element he or she mixed with another to form a given compound, the results of the experiment are useless. In order to share information and communicate the results of experiments, then, scientists need a standardized “vocabulary” of measures.
This “vocabulary” is the International System of Units, known as SI for its French name, Système International d’Unités. By international agreement, the worldwide scientific community adopted what came to be known as SI at the 9th General Conference on Weights and Measures in 1948. The system was refined at the 11th General Conference in 1960, and given its present name; but in fact most components of SI belong to a much older system of weights and measures developed in France during the late eighteenth century.
HOW THE ENGLISH SYSTEM WORKS (OR DOES NOT WORK)
Like methods of counting described above, most systems of measurement in premodern times were modeled on parts of the human body. The foot is an obvious example of this, while the inch originated from the measure of a king’s first thumb joint. At one point, the yard was defined as the distance from the nose of England’s King Henry I to the tip of his outstretched middle finger.
Obviously, these are capricious, downright absurd standards on which to base a system of measure. They involve things that change, depending for instance on whose foot is being used as a standard. Yet the English system developed in this willy-nilly fashion over the centuries; today, there are literally hundreds of units - including three types of miles, four kinds of ounces, and five kinds of tons, each with a different value.
What makes the English system particularly cumbersome, however, is its lack of convenient conversion factors. For length, there are 12 inches in a foot, but 3 feet in a yard, and 1,760 yards in a mile. Where volume is concerned, there are 16 ounces in a pound (assuming one is talking about an avoirdupois ounce), but 2,000 pounds in a ton. And, to further complicate matters, there are all sorts of other units of measure developed to address a particular property: horsepower, for instance, or the British thermal unit (Btu).*
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* Excerpt from “Science of Everyday Things”, by Judson Knight. Gale Group, 2002.
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