Americans in Great Measure

摘要

On World Metrology Day, 20 May 2019, all of the USMA officers had the honor of being present at the National Institute of Standards and Technology (NIST) Headquarters in Gaithersburg MD, on an historic day for measurement. That was the day that the last earthly tie of the International System of Units (the SI) to any nation was severed. On that day, four of the seven SI base units, the kilogram, ampere, kelvin, and mole, were redefined to be in agreement with the International System of Units. In the process, the definition of the kilogram as the mass of an international prototype was repealed. From that day forward, world measurement was freed from its last physical limitation: the risk of the decay or purloin of any physical object.