
Scientists Are About to Redefine the Kilogram and Shake Up Our System of Measures
by Jay Bennett Smithsonian.com
Locked in a vault that requires three keys to open, in the town of Sèvres just to the southwest of Paris, there is a kilogram. Actually, it’s The Kilogram, the International Prototype of the Kilogram (IPK), the kilogram against which all other kilograms must take their measure, Le Grand K. This cylinder of platinum-iridium alloy sits under three protective glass bells, in a temperature- and humidity-controlled environment, in a safe along with six official copies, in the underground vault of Sèvres.
“If you were to drop it, it would still be a kilogram, but the mass of the whole world would change,” says Stephan Schlamminger, a physicist with the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland.
The IPK only emerges from its vault every 40 years or so, when the golf-ball-sized ingot, exactly a kilogram by definition since 1889, is used to calibrate copies that are shared with countries around the world. But there is a problem. In the vault with the IPK are six témoins, or “witnesses”—the official copies. Over the years, as evidenced by the rare occasions when Le Grand K and its witnesses have been measured, the mass of the IPK has “drifted.”

Carol graduated from Riverside White Cross School of Nursing in Columbus, Ohio and received her diploma as a registered nurse. She attended Bowling Green State University where she received a Bachelor of Arts Degree in History and Literature. She attended the University of Toledo, College of Nursing, and received a Master’s of Nursing Science Degree as an Educator.
She has traveled extensively, is a photographer, and writes on medical issues. Carol has three children RJ, Katherine, and Stephen – one daughter-in-law; Katie – two granddaughters; Isabella Marianna and Zoe Olivia – and one grandson, Alexander Paul. She also shares her life with her husband Gordon Duff, many cats, and two rescues.
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