Slashdot Mirror
Kilogram Conflict Resolved At Last (nature.com)
An anonymous reader writes: As the capabilities of science and engineering expand, they rely more on the precision of measurements. It's vitally important, then, to make sure the standard units underpinning those measurements don't change. This is a problem for the kilogram. For years, it has remained the only SI unit based on a physical object — a small cylinder of platinum and iridium. Scientists have been arguing about how to replace it for decades, but now it looks like their efforts are finally reaching fruition. They finally have all the data they need to define the kilogram with mathematical constants, which solves the problem of the variability of physical objects. "One method, pioneered by an international team known as the Avogadro Project, involves counting the atoms in two silicon-28 spheres that each weigh the same as the reference kilogram. This allows them to calculate a value for Avogadro's constant, which the researchers convert into a value for Planck's constant. Another method uses a device called a watt balance to produce a value for Planck's constant by weighing a test mass calibrated according to the reference kilogram against an eletromagnetic force." Further research has narrowed down the value of Planck's constant, and experimental data from standards bodies is finally matching up. "If they are proved right, in 2018, Le Grand K will join the meter as a museum piece."
what, out of interest, is your best pro-imperial argument?
Personally a fan of Metric, but Imperial does have one major thing going for it - Easy divisibility by low prime numbers.
In the modern world, almost no one "does" math anymore. We use a computer or a calculator, and just get the answer. Shifting up or down by powers of ten makes for convenient readability, but otherwise doesn't matter in the least. Computers would actually work better if we switched to all binary, and wouldn't work any worse if we still used Imperial.
For most of human history, however, having units of measurement easily divisible into 2/3/4/5/6/8/9/10/12/etc parts meant that your average math-illiterate farmer or carpenter could still successfully figure out how to use a pair of oxen to spread four bushels of seed over a virgate (with a peck left over), or five cords of wood into 128 days of winter, and so on. No one cared about the weight of supper in terms of the speed of light in a vacuum, they cared about having enough to heat and eat through the winter.