Oak Ridge National Laboratory Main Campus

National Institute of Standards and Technology speakers will join Oak Ridge National Laboratory on Monday, to honor World Metrology Day.

The worldwide celebration pays tribute to the signature of the Metre Convention on May 20, 1875. Representatives of 17 nations signed, and the convention set framework in the science of measurement and its industrial, commercial and societal application for worldwide collaboration through the SI, or metric, system.

This year, the international system of units, known as the SI, will officially be redefined after a culmination of 40 years of scientific efforts to redefine the kilogram. A group of 60 countries unanimously voted to change the definition at a conference in Versailles, France on November 16, 2018.

“We are truly honored to be joining the world community in taking this historic step that will accelerate innovation and usher in a new era of advancement for science and industry,” Under Secretary of Commerce for Standards and Technology and Director of the National Institute of Standards and Technology Walter G. Copan said in November. “NIST researchers have played a key role in this historic redefinition, and I am proud of them and their many colleagues from around the world who have made this foundational achievement possible.”

Since 1889, the kilogram has been defined by a platinum-iridium cylinder that is located in Paris, France and named the International Prototype of the Kilogram. A formal agreement in November 2018 acknowledged that May 20, 2019 will mark the redefinition: “as a function of natural constants, notably the Planck constant.”

Planck's constant is fundamental, equaling the energy of a quantum of electromagnetic radiation, divided by its frequency, for a value of 6.626 x 10-34 joule-seconds.

With the elimination of the IPK, the seven base SI units will no longer be dependent on a physical artifacts for their definitions.

“This is really a pivot point for humanity,” Jon Pratt, who has been a longtime researcher and supervisor for the NIST group working to redefine the kilogram with nature’s fundamental laws, said in November. “We can now measure everything more accurately using knowledge of how the universe operates at the atomic level than we can using objects we can can see and feel.”

In conjunction with the National Conference of Standards Laboratories, ORNL will host three members of the NIST team- Leon Chao, Alireza Panna and Shamith Payagala- who were instrumental in determining the new value of Planck's constant through the development of the NIST-4 Kibble Balance.

Chao, Panna and Payagala will discuss the redefinition, the Kibble Balance and its role. Additional presentations will include current and anticipated future capabilities to realize the base SI units directly at ORNL and tours of the ORNL Metrology Laboratory facilities.

Presentations and the meeting will be offered to ORNL employees as a continuation of the “Making Good Measurements” seminar series. Beginning at 8 a.m in Building 4500-North, Wigner Auditorium, registration can be made through Vickie Hendrickson by email at vh9@ornl.gov or phone at 865-241-4679.

“The SI unit system will finally be a truly universal system, free of any human artifacts,” aerospace engineer Max Fagin, whose tweets about metrology went viral late last year, said. “And that to me is a profoundly beautiful thing.”

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