February 26, 2005
Redefining the Kilogram
Interesting news item at Slashdot today.
Experts Suggest Replacing Definition of Kilogram
“The kilogram is the only one of the seven basic units of the international measurement system defined by a physical artifact rather than a natural phenomenon. International team of scientists suggest replacing the kilogram artifact — a cylinder of platinum-iridium alloy about the size of a plum —with a definition based on one of two unchanging natural phenomena, either a quantity of light or the mass of a fixed number of atoms. They propose to adopt either one of two definitions for the kilogram by selecting a specific value for either the Planck constant or the Avogadro number.”
Makes a lot of sense. It's hard to calibrate something when the only standard is locked away in a vault. The Planck's Constant is very elegant and simple — something that any competent lab person could whip up…
Here's an image of the Kilogram Standard:
Comments
Basing it off of Avogadro's number makes more sense IMNSHO. 10^23 atoms isn't _too_ far out of our direct observation range. We've become exceedingly good at making near perfect silicon crystals for some reason....
Posted by: Al at February 26, 2005 07:07 PMPost a comment