| Abstract | The world of measurement is changing. Fundamental constants of nature are replacing artefacts as the basis for defining units of measure. On World Metrology Day, May 20, the last artefact, the international prototype kilogram (IPK), or "the grand k," was replaced by Planck’s constant in defining the unit of mass, the kilogram. The redefinition does not change the numbers much, and few labs will notice any difference. In the grocery store, apples will still be apples and the price, whether by kilogram or by pound, certainly will not change as a result of the redefinition |
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