I love stuff like this.
In the 120 years since No. 20 and several dozen other exact copies were crafted in France to serve as the world's standards of the kilogram, their masses have been mysteriously drifting apart.The difference is on average about 50 micrograms -- about the weight of a grain of fine salt. But the ramifications have rippled through the world of precision physics, which uses the kilogram as the basis for a host of standard measures, including force of gravity, the ampere and Planck's constant -- the omnipresent figure of quantum mechanics.In essence, no one really knows today what a kilogram is."How do I trust what I have?" asked Zeina Jabbour, the physicist at the National Institute of Standards and Technology, or NIST, in charge of maintaining No. 20, the official U.S. kilogram.The kilogram crisis has kicked off an international race to redefine the measure.
The difference is on average about 50 micrograms -- about the weight of a grain of fine salt. But the ramifications have rippled through the world of precision physics, which uses the kilogram as the basis for a host of standard measures, including force of gravity, the ampere and Planck's constant -- the omnipresent figure of quantum mechanics.
In essence, no one really knows today what a kilogram is.
"How do I trust what I have?" asked Zeina Jabbour, the physicist at the National Institute of Standards and Technology, or NIST, in charge of maintaining No. 20, the official U.S. kilogram.
The kilogram crisis has kicked off an international race to redefine the measure.
― Ned Raggett, Thursday, 17 April 2008 03:28 (seventeen years ago)
A race! I love that. Who's going to be the first to define the kilogram?!
― Aimless, Thursday, 17 April 2008 03:42 (seventeen years ago)
Isn't/shouldn't the kilo defined by a certain volume of water?
― Catsupppppppppppppp dude 茄蕃, Thursday, 17 April 2008 03:44 (seventeen years ago)
the density's not constant enough
― moonship journey to baja, Thursday, 17 April 2008 04:09 (seventeen years ago)
also it evaporates
― moonship journey to baja, Thursday, 17 April 2008 04:15 (seventeen years ago)
ok an inert gas at stp
― Catsupppppppppppppp dude 茄蕃, Thursday, 17 April 2008 04:27 (seventeen years ago)
so now we're trying to control three variables?
― moonship journey to baja, Thursday, 17 April 2008 05:03 (seventeen years ago)
it should be the exact weight of an angel's liver
― latebloomer, Thursday, 17 April 2008 05:08 (seventeen years ago)
my favorite proposal is the carbon-12 cube because it simultaneously defines avogadro's number, the kilogram and the AMU
― moonship journey to baja, Thursday, 17 April 2008 05:09 (seventeen years ago)
how can i trust my dealer now?
― gershy, Thursday, 17 April 2008 05:15 (seventeen years ago)
:D
Awesome way to 'scuse a dud deal tho. "sorry, sunspots."
― Trayce, Thursday, 17 April 2008 05:35 (seventeen years ago)
OMG moonship I am in love with the idea of that carbon cube.
― Abbott, Thursday, 17 April 2008 15:50 (seventeen years ago)
I'm kind of sad the original kilogram is in the shape of a cylinder.
― Abbott, Thursday, 17 April 2008 15:52 (seventeen years ago)
http://i26.tinypic.com/15zqiwh.gif
That's cylinderist!
― StanM, Thursday, 17 April 2008 16:44 (seventeen years ago)
-- Catsupppppppppppppp dude 茄蕃, Thursday, 17 April 2008 05:27 (13 hours ago) Bookmark Link
STP and all derived units are defined in terms of the definitions of the units of mass, length and time, so you can't define mass in terms of STP without pulling yourself up by your bootstraps.
Practically useful absolute definitions of length and time are easy but mass is not so simple so they go with "1 kg = this thing in Paris".
― caek, Thursday, 17 April 2008 17:36 (seventeen years ago)
or the atom counting carbon thing, which is implicit in a lot of chemistry but not yet practical, I suspect.
― caek, Thursday, 17 April 2008 17:38 (seventeen years ago)
i would very much like it if the kilogram was based on http://imagecache2.allposters.com/images/pic/RSPOD/RS753~Stone-Temple-Pilots-Rolling-Stone-no-753-February-1997-Posters.jpg
― max, Thursday, 17 April 2008 17:41 (seventeen years ago)
You mean the weight of Weiland's useless head?
― Ned Raggett, Thursday, 17 April 2008 17:45 (seventeen years ago)
Oh surely that's a couple of kilos.
― Abbott, Thursday, 17 April 2008 18:35 (seventeen years ago)