Post by Warrigal on Nov 16, 2018 19:50:14 GMT -5
Scientists have voted to redefine the value of a kilogram, in what they called a landmark decision that will boost the accuracy of scientific measurements.
Scientists for whom the update represents decades of work clapped, cheered and even wept as the 50-plus nations one by one said "yes" or "oui" to the update in the French city of Versailles on Friday (local time).
Nobel prize winner William Phillips called it "the greatest revolution in measurement since the French revolution", which ushered in the metric system of metres and kilograms.
The so-called "Grand K" kilogram, a cylinder of polished platinum-iridium alloy that has been the world's sole true kilo since 1889, is to be retired. Nations instead approved the use of a scientific formula to define the exact weight of a kilogram. It will mean redundancy for the Grand K and its six official copies.
The new formula-based definition of the kilogram will have multiple advantages over the precision-crafted metal lump that has set the standard for more than a century.
Unlike a physical object, the formula cannot pick up particles of dust, decay with time or be dropped and damaged.
It also is expected to be more accurate when measuring very small or very large masses.
Even in retirement, the Grand K and its copies — collectively known as "the heir and the spares" — will still be kept in the high-security vault on the outskirts of Paris where they are stored.
That's because scientists want to keep on studying them, to see whether their masses gradually change over time.
More here: www.abc.net.au/news/2018-11-17/kilogram-weight-overhauled-by-scientists-in-historic-vote/10506974
