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 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 official US kilogram — the physical prototype against which all weights in the United States are calibrated — cannot be touched by human hands except in rare circumstances. Sealed beneath a bell ...

How much is a kilogram? 1,000 grams. 2.20462 pounds. Or 0.0685 slugs based on the old Imperial gravitational system. But where does this amount actually come from and how can everyone be sure they are ...

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 ...

Physics is a funny thing. Despite dictating the behaviors and states of everything from atoms to stars, our interpretation of its effects are rooted in very human constructs. Meters, amperes and ...

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 ...

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, ...