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The kilogram doesn't weigh a kilogram any more. This sad news was announced during a seminar at CERN on Thursday, 26 October by Professor Klaus von Klitzing, who was awarded the 1985 Nobel Prize in Physics for the discovery of the quantised Hall effect. "We are about to witness a revolutionary change in the way the kilogram is defined," he declared.
Together with six other units – metre, second, ampere, kelvin, mole, and candela – the kilogram, a unit of mass, is part of the International System of Units (SI) that is used as a basis to express every measurable object or phenomenon in nature in numbers. This unit's current definition is based on a small platinum and iridium cylinder, known as "le grand K", whose mass is exactly one kilogram. The cylinder was crafted in 1889 and, since then, has been kept safe under three glass bell jars in a high-security vault on the outskirts of Paris. There is one problem: the current standard kilogram is losing weight. About 50 micrograms, at the latest check. Enough to be different from its once-identical copies stored in laboratories around the world.
To solve this weight(y) problem, scientists have been looking for a new definition of the kilogram.
Dang. That throws the easily memorable conversion of 1kg=2.2lbs right out the window.
(Score: 3, Informative) by maxwell demon on Tuesday November 07 2017, @05:50AM (1 child)
Strictly speaking, yes. But I doubt that there exists any scales that is precise enough to detect the difference. Especially given that it probably will be dwarfed by the mass differences between two different moles of graphite caused by the statistical fluctuation of the isotopic composition (that is, one of the graphite probes almost certainly will have a few more 13C atoms than the other).
The Tao of math: The numbers you can count are not the real numbers.
(Score: 4, Informative) by Anonymous Coward on Tuesday November 07 2017, @06:21AM
You are wrong about the statistical fluctuations which are 10^-14 for one mole. The binding energy difference of 2kJ/mole between graphite and diamond changes the mass by 180 times more.