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scpg02
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A better definition for the kilogram? Scientists propose a pContact: John Toon
jtoon@gatech.edu
404-894-6986
Georgia Institute of Technology Research News
A better definition for the kilogram? Scientists propose a precise number of carbon atoms
| Quote: | How much is a kilogram?
It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from platinum and iridium and known as the International Prototype Kilogram or “Le Gran K” – has been losing mass, about 50 micrograms at last check. The change is occurring despite careful storage at a facility near Paris.
That’s not so good for a standard the world depends on to define mass.
Now, two U.S. professors – a physicist and mathematician – say it’s time to define the kilogram in a new and more elegant way that will be the same today, tomorrow and 118 years from now. They’ve launched a campaign aimed at redefining the kilogram as the mass of a very large – but precisely-specified – number of carbon-12 atoms. |
http://www.eurekalert.org/pub_releases/2007-09/giot-abd092107.php
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Andre
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Thanks Maggie, it used to be the mass of one liter of water at a certain temperature. Problem of course in what ratio of heavy isotopes.
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