On the morning of Friday, November 16, scientists and diplomats crammed into an auditorium in Versailles, a stone’s throw from the Sun King’s gilded chateau. Patrick Abbott, an American physicist, had ...

Deep underneath the Parisian suburb of Saint-Cloud, in a vault that can only be opened by three people wielding three different keys, there lies a hunk of metal that is so crucial to the world of ...

We measure stuff all the time—how long, how heavy, how hot, and so on—because we need to for things such as trade, health and knowledge. But making sure our measurements compare apples with apples has ...

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 ...

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 ...

Since 1889, human civilization has depended upon a magic rock. Known as Le Grand K, it sits under protective glass in St. Cloud, France. Humanity's magic rock is actually a chunk of metallic alloy ...

The kilogram is losing weight and many scientists agree that it's time to redefine it. They are hoping to redefine the kilogram by basing it on standards of universal constants rather than on an ...

The kilogram has the dubious distinction of being the only SI unit still based on a physical object; specifically, a metal cylinder kept in a vault in France. Plans are well underway to redefine the ...

The kilogram — anywhere in the world, for any purpose — is based on the exact weight of a golf-ball-sized chunk of platinum and iridium stored under three glass bell jars in a vault in an ornate ...

Your support goes further this holiday season. When you buy an annual membership or give a one-time contribution, we’ll give a membership to someone who can’t afford access. It’s a simple way for you ...