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 ...

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 ...

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 ...

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 ...

The international prototype kilogram is a cylinder of platinum and platinum-iridium alloy, which is kept at the International Bureau of Weights and Measures (BIPM) near Paris. The kilogram may need to ...

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 ...

GAITHERSBURG, MD. — Forty feet underground, secured in a temperature- and humidity-controlled vault here, lies Kilogram No. 20. It’s an espresso-shot-sized, platinum-iridium cylinder that is the ...

The 'one kilogram to rule them all' was cast in platinum and iridium in 1879 and is kept in a triple-locked vault THE world says goodbye to the original kilogram on May 20, on World Metrology Day.

Humanity is on the verge of a weighty achievement. On Friday, representatives of more than 60 nations will convene in Versailles, France, to approve a new definition for the kilogram. Since the 19th ...

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 ...

Appearance: It's not about what it looks like; it's about what it weighs. And how much does it weigh? It weighs a kilogram. And how much is that? A thousand grams. And how much does a gram weigh?