This makes bouncing up and down the scale easy. ![]() The metric system is based on units of 10: There are 10 millimeters in a centimeter, 10 centimeters in a decimeter, 10 decimeters in a full meter, and so on. Units were often divvied up in maddening ways as well. Read: Why doesn’t the United States use the metric system? Cloth wholesalers might use one length, cloth retailers another, and fishermen measured the width of their nets using one unit and the breadth using another. In medieval Geneva, a “pound” could be 15, 16, or 18 ounces, depending on the goods being sold. A “bushel” in one town wasn’t the same as a “bushel” in another. Way back when, the same units often differed significantly from village to village. Look how far we’ve come! And it’s true that the kilogram and other components of the metric system (the official standard everywhere in the world save Burma, Liberia, and the United States) do seem eminently rational compared to the metrological chaos of yesteryear. Stories about this new, universal kilogram usually portray it as a triumph of progress. (You can read about the new definitions here and here.) But far from simply tidying up a few loose metrological ends, these new definitions will also close a chapter on our past-an era when units of measure weren’t just humdrum tools, but a real frontier in the struggle for equality. The new definition will be based on universal constants of nature-quantities that don’t change, like the charge of an electron-which will allow any lab around the world to reproduce a one-kilogram mass on its own by rigging up the right equipment. ![]() But it also has a problem: On an infinitesimal level, its mass has changed over the years, causing all sorts of complications. This cylinder has, by definition, a mass of 1.0000 … kilogram, to as many decimal places as you like. The kilogram is the very last international unit based on a human-made object: a platinum-iridium cylinder in an underground, high-security vault in Paris. Next month, the 26th meeting of the General Conference on Weights and Measures will likely adopt new methods of defining four basic international units, including the kilogram. Using a ruler or scale might not seem like a political act, but according to the late Polish historian Witold Kula, in his book Measures and Men, units of length, weight, and volume in the past were both “instrument of asserting class privilege” and “the center of a bitter class struggle” dating back several millennia. Fluctuating units also helped concentrate power in the hands of despots. In centuries past, lords and ministers in Europe and beyond often manipulated units to steal land, fix commodities markets, cheat peasants out of goods, and wring extra labor and taxes out of them. But to historians of metrology-the study of measurement-those innocuous-looking units are something else entirely: the culmination of a long, fraught battle against tyranny. ![]() To scientists, they’re the very standards that allow for meaningful comparisons of experiments. To most Americans, these units of measurement are little more than funny inconveniences on trips abroad.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |