The supreme arbiter of mass for humankind is a polished cylinder of platinum alloy just smaller than a golf ball. It was cast in London in 1879, unveiled a decade later in a ceremony in France, and ...

A kilo is a kilo is a kilo, right? Wrong. Monday marks World Metrology Day, and this year’s edition sees a big change in the way the kilogram unit is defined. In November last year, scientists and ...

After more than a century, the international prototype kilogram – a cylindrical chunk of metal stored in a French vault – doesn't weigh the same as its 40 replicas, distributed worldwide and used to ...

When we measure the world, we measure it using base units like 'foot,' 'mile,' 'meter,' and 'second.' But who decides how big those units of measurement are? In the United States, those units are ...

The kilogram may need to go on a diet. The international standard, a cylinder-shaped hunk of metal that defines the fundamental unit of mass, has gained tens of micrograms of MASS from surface ...

How much is a kilogram? It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from ...

One of the most iconic hunks of metal in the world is set to get a demotion. The official metallic cylinder that defines the mass of a kilogram may soon be set aside in favor of a measurement that is ...

In a subterranean vault in a suburb of Paris lies a small, rarely seen metal cylinder known as Le Grand K. For 130 years, this golf-ball-sized hunk of 90% platinum and 10% iridium has served as the ...

Scientists from around the world are gathering in France today to decide the fate of the kilogram. For nearly 130 years, the kilogram has been based on a lump of metal called the Big K, locked in a ...

THE kilogram, the scientific unit of mass, is defined by a cylindrical lump of platinum and iridium, made in 1879 and stored in Paris. There are also around 40 copies of it in scientific ...

Get unlimited access to ad-free articles and exclusive content. The kilogram may need to go on a diet. The international standard, a cylinder-shaped hunk of metal that defines the fundamental unit of ...