New York TimesThe Kilogram is Dead. Long Live the Kilogram!New York TimesSince 1889, Le Grand K, a sleek cylinder of platinum-iridium metal, has ruled from its underground vault in Paris. An absolute monarch, it was the very definition of one kilogram of mass. Scientists from around the world made pilgrimages to it ...kilogram gets a new definitionBBC NewsScientists say goodbye to physical definition of the kilogramThe VergeFor decades, the kilogram was based on a hunk of metal.