The official definition of a kilogram has been changing for well over a century, but this week it may be redefined for the final time. After years of debate and discussion, scientists from around the ...

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 ...

The Latest on a scientific meeting on how to define weights and measures (all times local): 1:35 p.m. The international system of measurements has been overhauled with new definitions for the kilogram ...

Starting this November, the kilogram, along with three other units of measurement (the kelvin, the mole, and the ampere), will be redefined. But don’t worry, ...