In a historic vote, nations on Friday unanimously approved a ground-breaking overhaul to the international system of measurements that underpins global trade and other vital human endeavours, uniting together behind new scientific definitions for the kilogram and other units in a way that they have failed to do on so many other issues.
Scientists, for whom the update represents decades of work, clapped, cheered and even wept as the 50-plus nations gathered in Versailles, west of Paris, one by one said B次元官网网址測esB次元官网网址� or B次元官网网址渙uiB次元官网网址� to the change, hailed as a revolution for how humanity measures and quantifies its world.
The redefinition of the kilogram, the globally approved unit of mass, was the mostly hotly anticipated change. For more than a century, the kilogram has been defined as the mass of a cylinder of platinum-iridium alloy kept in a high-security vault in France. That artefact, nicknamed B次元官网网址淟e Grand K,B次元官网网址� has been the worldB次元官网网址檚 sole true kilogram since 1889.
But now, with the vote, the kilogram and all of the other main measurement units will be defined using numerical values that fit handily onto a wallet card. Those numbers were read to the national delegates before they voted.
Scientists at the meeting were giddy with excitement: some even sported tattoos on their forearms that celebrated the science.
Today, in a landmark decision, representatives from 60 countries voted to redefine the SI, changing the worldB次元官网网址檚 definition of the kilogram, ampere, kelvin and mole, forever!
B次元官网网址� NPL (@NPL)
Nobel prize winner William Phillips called the update B次元官网网址渢he greatest revolution in measurement since the French revolution,B次元官网网址� which ushered in the metric system of meters and kilograms.
Jon Pratt of the U.S. National Institute of Standards and Technology said the vote left him B次元官网网址渁 basket caseB次元官网网址� and B次元官网网址渆xtremely emotional.B次元官网网址�
B次元官网网址淭hose units, those constants chosen now, include everything we know, everything we have always known and provide that springboard for us to go pursue those things that we donB次元官网网址檛 know,B次元官网网址� he said. B次元官网网址淭hat was just leaving me in a puddle of tears.B次元官网网址�
The Grand K and its six official copies, kept together in the same safe on the edge of Paris and collectively known as the B次元官网网址渉eir and the spares,B次元官网网址� will be retired but not forgotten. Scientists want to keep studying them to see whether their masses decay over time.
IT'S OFFICIAL B次元官网网址� the science community has voted! All of the SI units will be defined by fundamental constants of nature as of 20 May 2019!
B次元官网网址� NPL (@NPL)
The change will have no discernable impact for most people. Bathroom scales wonB次元官网网址檛 suddenly get kinder and kilos and grams wonB次元官网网址檛 change in supermarkets.
But the new formula-based definition of the kilogram will have multiple advantages over the precision-crafted metal lump that set the standard from the 19th century to the 21st, through periods of stunning human achievement and stunning follies, including two world wars.
Unlike a physical object, the new formula for the kilo, now also known as B次元官网网址渢he electric kilo,B次元官网网址� cannot pick up particles of dust, decay with time or be dropped and damaged.
It is expected to be more accurate when measuring very, very small or very, very large masses and help usher in new innovations in science, industry, climate study and other fields.
鈿狅笍 The Kg is dead! Long life to the Kg. 鈿狅笍 Today, last day of week, delegates from 60 countries will to fix the value of Planck constant to an exact number. Le Grand K will no longer be a standard as the Kg will be defined using mc2=hv 馃
B次元官网网址� Teodoro Laino (@teodorolaino)
With time, as the science behind the new definition becomes more accessible and affordable, it should also mean that countries wonB次元官网网址檛 have to send their own kilograms back to France to be checked occasionally against Le Grand K, as they have done until now, to see whether their mass was still accurate.
John Leicester, The Associated Press
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