A New Definition for the Kilogram

It looks like after this week the accepted SI unit of mass, the last fundamental unit of measure to be defined by a physical artifact, will be redefined in terms of fundamental constants of physical theory.


The kilogram is dead; long live the kilogram

Nearly every measurement of weight you’ve ever made, from peeking at your bathroom scale to measuring out flour for a recipe, can be traced back to just a single object: a metal kilogram made of platinum and iridium that resides under lock and key in an underground vault in Paris. It’s called the International Prototype Kilogram, or IPK, and since its creation in 1889 it has been the standard by which the world’s weights are defined. But not for much longer.

That one chunk of platinum and iridium has defined the kilogram for over a century. This is not an event that happens every day….

Message Board: Join in our discussion.