I thought this was an interesting read and wanted to share it with you all.
http://www.theage.com.au/news/national/making-an-exact-difference/2007/06/14/1181414466901.html"Scientists will use the spheres to determine how many silicon atoms make up a kilogram, and this will be used as the new definition — bringing the kilogram into line with other base units such as the metre and the second, which are all defined by physical constants."
Regards, Mike
