From Platinum to Planck: The biggest revolution in metrology since the French Revolution

Who: Carl Williams, NIST
Thursday, January 31, 2019 - 4:00pm
104 Thaw Hall

The International System of Units (SI) is the basis for measurements worldwide, and NIST, as the premier National Metrology Institute, has both shaped the development of the SI and led its implementation.  On November 16, 2018 the Member States of the Treaty of the Meter voted to revise the International System of Units (SI), changing the world's definition of the kilogram, the ampere, the kelvin and the mole.   This decision occurred at the 26th meeting of the General Conference on Weights and Measures (CGPM) in Versailles, France, means that all SI units will now be defined in terms of constants that describe the natural world. This will assure the future stability of the SI and open the opportunity for the use of new technologies, including quantum technologies, to implement the definitions.  The actual revision official will come into force on World Metrology Day, 20 May 2019.  In the reformed SI, all of the base units will be defined by reference to unchanging constants of nature, finally eliminating any connection between units and special artifacts.  This talk will describe why such a radical change was needed; how it is being achieved, in large part driven by work done at NIST; and how new technologies are transforming how we realize and disseminate the SI.