The NIST-4 Kibble balance, an electromagnetic weighing machine that is used to measure Planck's constant, and in turn, redefine the kilogram. Jennifer Lauren Lee / NIST Locked in a vault that requires ...

We’ve long known that there were some issues with France’s ‘Le Grand K’, the international prototype for what a kilogram really is. Made in 1879 from platinum and iridium alloy, it is the perfect ...

Mass is a property of matter which is not dependent on the temperature of the object in space. The SI unit of mass is kilogram (kg). The prototypes of the International standard kilogram is available ...

Since 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 1 kilogram of mass. Scientists ...

More than a century ago, a small metal cylinder was forged in London and sent to a leafy suburb of Paris. The cylinder was about the size of a salt shaker and made of an alloy of platinum and iridium, ...

is a senior reporter who has covered AI, robotics, and more for eight years at The Verge. Update, May 20th, 2019, 10AM ET: This article was originally published in November 2018. As of May 20th, 2019, ...