The International Prototype of the Kilogram (IPK) is held in an underground vault at the International Bureau of Weights and Measures (BIPM), located in Sèvres, near Paris. Following the decision to redefine the SI kilogram starting 20th May 2019, the definition of the kilogram will no longer be based on the physical artefact called the International Prototype but rather on a constant of physics, as are the other seven base units of the SI. The redefinition of the kilogram marks the end of artefacts used to define our measurement units. Credit: © BIPM
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