How much is a kilogram? It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from ...

There is a new standard in town, and it's sort of a big deal. This new standard is the definition of the kilogram, the unit of mass in the SI system—the International System of Units). It replaces the ...

How we measure the world underwent a quantum leap on Monday as scientists adopted new hyper-accurate definitions for units of weight, electricity and temperature derived from the universal laws of ...