New Short Film Takes You on the Journey to Redefine the Kilogram

In an impressive act of cooperation, the General Conference of Weights and Measures member states voted to adopt a new kilogram definition for the first time since instituting the international prototype kilogram, or IPK, in 1889. This was the culmination of the years-long effort to create greater constancy in mass measurement examined in ‘Everything Different, Nothing Changes: Redefinition of the SI Unit Kilogram’, a new short video by Mettler Toledo. 

At a basic level, all standards including mass are now tied to fundamental natural constants. In the case of mass, the referenced value is the Planck constant, also known as the fundamental constant of quantum physics. 

In the 20-minute piece, Christian Müller-Schöll, Mettler Toledo, Dr Richard Davis, BIPM, and other metrology experts including Dr Philippe Richard, METAS, explore the science behind the definition, as well as the nearly poetic way the definition was able to be proven. This combination of smart thinking and technological excellence has produced measurement accuracy that is accessible for all people in all places at all times.
Rare footage takes you inside areas normally reserved for only a few metrology experts to witness everything from the highly technical Kibble balance used to calibrate reference artifacts to equipment used to create the enriched silicon sphere that was also part of the proof. These strong visuals help to make real the ongoing discussion around the kilogram, a discussion that can seem largely theoretical, especially to those accustomed to dealing with physical weights.

The new kilogram definition eliminates the need to rely on a physical object located in one place, providing a limitless and previously unimaginable access to mass-measurement accuracy. “We are pleased to have been part of the effort to make this new definition a reality,” said Mr Müller-Schöll.

To see a brief, exciting trailer for the video, please visit

To view “Everything Different, Nothing Changes” in its entirety, please visit