WIKIMEDIA COMMONS, POUSSIN JEAN
There's a secret war going on, and the future of science is at stake. The battle rages over the definition of "kilogram." Like many standards of measurement, the definition of a kilogram harkens back to scientific days of yore, when researchers were just beginning to empirically grasp the composition of matter. Since 1889, the kilogram has been defined as the mass of a certain platinum-iridium cylinder, called Le Grande K, that is housed at a sealed and guarded vault in Paris. In order for the cylinder to weigh exactly a kilogram, it must be taken out and cleaned according to strict rules. Invariably, such a process adds and subtracts millions of atoms—from cleaning products and simply handling the object—affecting the precise mass of Le Grande ...
