Scientists have changed the way the kilogram is defined.
Currently, a kilogram is defined by the weight of a platinum-based block called “Le Grand K” which is locked away in a safe in Paris.
However, researchers meeting in Versailles voted to get rid of it in favour of defining a kilogram in terms of an electric current.
The decision was made at the General Conference on Weights and Measures.
Why kill off the kilogram?
Le Grand K has been the way of measuring weight for some time. But the master kilogram and its copies have changed over the years – ever so slightly – as they deteriorated.
Over the years the change in the Le Grand K has been about 50 parts in a billion. This is about the weight of a single eyelash. But although it is tiny, the change can have important consequences.
The new electrical measurement is more stable and more accurate.