The National Institute of Advanced Industrial Science and Technology (AIST) showed Japan's meter and kilogram prototypes to the press on Monday, ahead of the 150th anniversary later this month of the ...

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 ...

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 ...

Breakthroughs, discoveries, and DIY tips sent every weekday. Terms of Service and Privacy Policy. This week, Sam Kean takes a look at some ridiculously precise ...

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 ...