A new way to measure Kilogram
From 2019 onwards, the kilogram will get more accurate. The new artefacts ought to derive from the constants of nature that are all interdependent. The kilogram was the only one among the units still pegged to a real object.
What Was the Earlier Measure of Kilogram?
For 125 years, a salt-shaker-sized cylinder, made of 90% platinum and 10% iridium, kept at the Bureau International des PoidsetMesures (BIPM), Paris, and weighing exactly a kilogram served as the definition of the measure. Since 1957 India’s National Physical Laboratory too has a replica of this measure and it has served as the reference.
Units of Measure No Longer Linked to Physical Objects
Several standard units such as second, metre, ampere, kelvin, mole, candela and kilogram are no longer defined by physical objects.
For instance, one metre was a platinum-iridium bar of that measure. In 1960, the metre was defined as the distance travelled by light in a vacuum in 1/299,792,458 seconds
Reason for Seprating Units from Objects
In essence, the units were freed from artefacts, because the artefacts are subject to wear and tear and thus may become a source of error in measurement.