History Recent history of measurement of 1 kg and other units

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Lavoisier's execution at the guillotine is noted, emphasizing the historical context of scientific advancement. The Avogadro project aims to redefine Avogadro's constant, currently linked to the kilogram, by creating an exceptionally precise silicon sphere. This initiative seeks to reverse the relationship, allowing the kilogram to be defined by Avogadro's constant instead. The project highlights the significant effort and precision involved in establishing fundamental measurements, illustrating how standards have evolved over time. The discussion reflects a fascination with the complexities of defining the kilogram and the historical implications of scientific figures like Lavoisier.
Astronuc
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I didn't remember the Lavoisier died at the guillotine.

The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram. I knew about the Pt the Pt-Ir standard. I didn't realize that the mass of various 'standards' changed in time.



Originally published Mar 25, 2013Edit/update: From the Youtube page -
The Avogadro project aims to redefine Avogadro's constant (currently defined by the kilogram -- the number of atoms in 12 g of carbon-12) and reverse the relationship so that the kilogram is precisely specified by Avogadro's constant. This method required creating the most perfect sphere on Earth. It is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. This allows for a very precise determination of Avogadro's constant.
 
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Astronuc said:
I didn't remember the Lavoisier died at the guillotine.
That's what you get for being a tax collector :wink:
 


Wow, I had no idea about this project! It's amazing how much effort and precision goes into defining something as seemingly simple as the kilogram. And it's also interesting to learn about the history of the standard changing over time. Thanks for sharing this information!
 
Historian seeks recognition for first English king https://www.bbc.com/news/articles/c9d07w50e15o Somewhere I have a list of Anglo-Saxon, Wessex and English kings. Well there is nothing new there. Parts of Britain experienced tribal rivalries/conflicts as well as invasions by the Romans, Vikings/Norsemen, Angles, Saxons and Jutes, then Normans, and various monarchs/emperors declared war on other monarchs/emperors. Seems that behavior has not ceased.

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