Happy World Metrology Day!
This year’s celebration marks a particularly extraordinary change for the science of measurement and the entire field of calibration. Last November, representatives from 60 countries made the historic and unanimous decision to redefine the International System of Units. This redefinition takes each of the seven base units and connects them to fundamental constants within our universe. This marks perhaps the largest change since the French revolution and the standardization of the system itself. So, what does this mean for everyone? For most, this change will go relatively unnoticed. A kilogram of flour will still be a kilogram in the store. However, for science, this is a complete turning point.
SI Redefinition Benefits:
1.Basing the unit definitions on universal constants will eliminate the uncertainty that surrounds the old definitions. Previously, many of the base units relied on fallible standards such as the International Prototype Kilogram. Even with careful attention, physical objects like the IPK have changed over time. A system containing uncertainty at its core limits the ability to make accurate and precise measurements.
2.Removing the need to reference and trace back to one single master standard makes it possible to perform accurate measurements anywhere in the universe without the need to calibrate against another object.
For more information on all of the base units and the SI redefinition, check out NIST’s official page.