Non-standard uncertainties: Experiments in the visual conditions of the kilogram prototype

Abstract The kilogram prototype is an object manufactured in late nineteenth century to serve as the standard unit of mass worldwide. Since then, the kilogram definition has been determined by this unique object, making it a peculiar case in metrological studies. However, after realizing that the prototype’s mass was unexpectedly changing, scientists are seeking a new way to define the kilogram in pure mathematical terms.