A Better Definition for the Kilogram? Scientists Propose a Precise Integer Number of Carbon Atoms

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A computer-generated image of the International Prototype Kilogram which is made from an alloy of platinum and iridium. Image: Wikimedia Commons
A computer-generated image of the International Prototype Kilogram, which is made from an alloy of platinum and iridium. Image: Wikimedia Commons

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.


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Scientists demonstrate highly directional semiconductor lasers

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Jul 24, 2008 | User rating: not rated yet
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