It's official -- a kilogram isn't what it used to be
Source: Associated Press, via CBC
It's official -- a kilogram isn't what it used to be
Key measurement units kelvin, ampere and mole also get new definitions in Friday vote in France
The Associated Press · Posted: Nov 16, 2018 8:17 AM ET Last Updated: an hour ago
The international system of measurements has been overhauled with new definitions for the kilogram and other key units.
At a meeting in Versailles, France, countries have voted to approve the wide-ranging changes that underpin vital human activities like global trade and scientific innovation.
The most closely watched change was the revision to the kilo, the measurement of mass.
Until now, it has been defined as the mass of a platinum-iridium lump, the so-called Grand K, that is kept in a secured vault on the outskirts of Paris. It has been the world's one true kilo, against which all others were measured, since 1889.
Read more: https://www.cbc.ca/news/technology/kilogram-ampere-mole-definition-1.4908449
All that's left is for Betsy DeVos to require that the Biblical version be taught too.
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The Washington Post had a better story, but it was dated yesterday.
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Dave Weigel Retweeted
https://twitter.com/daveweigel
Are you ready to be inspired .... by measurement?
Tomorrow, people from around the globe will come together to *agree* on something, even though it is hard, even though it is costly, because it reflects a fundamental fact about the universe
Link to tweet
A massive change: Nations redefine the kilogram
https://www.washingtonpost.com/science/a-massive-change-nations-will-vote-to-redefine-the-kilogram/2018/11/15/b5704b0a-e6c7-11e8-b8dc-66cca409c180_story.html
By Sarah Kaplan November 15 at 7:27 PM
Humanity just made a weighty decision. On Friday, representatives of more than 60 nations, gathered in Versailles, France, approved a new definition for the kilogram.
Since the 19th century, scientists have based their definition of the fundamental unit of mass on a physical object -- a shining platinum iridium cylinder stored in a locked vault in the bowels of the International Bureau of Weights and Measures (BIPM) in Sevres, France. A kilogram was equal to the heft of this aging hunk of metal, and this cylinder, by definition, weighed exactly a kilogram. If the cylinder changed, even a little bit, then the entire global system of measurement had to change, too.
With Friday's vote, scientists redefined the kilogram for the 21st century by tying it to a fundamental feature of the universe -- a small, strange figure from quantum physics known as Planck's constant, which describes the smallest possible unit of energy.
Thanks to Albert Einstein's revelation that energy and mass are related, determining exactly how much energy is in that unit can let scientists define mass in terms of Planck's constant -- a value that should hold up across space and time -- rather than relying on an inconstant metal cylinder. (Mass determines something's weight, and for most purposes mass and weight are interchangeable.) ... The redefinition is the result of a decades-long, worldwide quest to measure Planck's constant precisely enough that the number would stand up to scientific scrutiny.
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Sarah Kaplan is a science reporter covering news from around the nation and across the universe. She previously worked overnights on The Washington Post's Morning Mix team. Follow https://twitter.com/sarahkaplan48
brooklynite
(94,745 posts)lagomorph777
(30,613 posts)That would mess up your diet for sure.
Zambero
(8,971 posts)A kilo then is not a kilo now???
dalton99a
(81,599 posts)mahatmakanejeeves
(57,622 posts)I would much rather have used that, but the timestamp was over 12 hours old.
packman
(16,296 posts)my teaspoon, tablespoon, pint, quart, ounce and pound. Good enuff for my mother's cookie recipes, good enuff for me. So there!
SeattleVet
(5,480 posts)I keep my kitchen scale on the grams setting, and have sets of measuring cups and spoons marked in milliliters. Any time I use an old recipe I either hand-write the real units on it, or make a change in the computer file before I re-save it.
I figure that the time spent doing that is almost made up for by not having to constantly convert, for instance, tablespoons to cups when multiplying a recipe.
We don't measure speed in furlongs per fortnight (by the way, that's US furlongs, which makes the speed of light 1.803e+12 furlongs/fortnight), so why base other measurements on, for example, the length of 3 barleycorns, or a king's body part?
JohnnyRingo
(18,650 posts)The kilo heretofore was defined by a lump of plutonium in a glass case. That was essential in the middle ages, but now we can define it more precisely with modern science.
Unfortunately, the article doesn't go into detail.
muriel_volestrangler
(101,377 posts)Because the radioactive disintegration would be constantly changing its mass. Plus, you know, the dangerous radioactivity.
JohnnyRingo
(18,650 posts)I think that displays pretty good reading skills for my advanced vintage. Can your president do that? hahaha
"Until now, it has been defined as the mass of a platinum-iridium lump, the so-called Grand K..."
missingthebigdog
(1,233 posts)Historic NY
(37,453 posts)JustABozoOnThisBus
(23,369 posts)Always less.
MineralMan
(146,333 posts)Now, everyone will have to throw out their old scales and buy new ones, see...
Still, If they're throwing out that cylinder of platinum and iridium, I'll take it. Yes, indeed.
Iggo
(47,571 posts)Is that wrong? (yes)
Was it always wrong? (i just looked it up and it's closer to 2.205 pounds)
What's the new conversion?
One kilo equals how many pounds?
lagomorph777
(30,613 posts)Can your scale do that?
Iggo
(47,571 posts)Cold War Spook
(1,279 posts)More I hope.