http://www.nzherald.co.nz/section/story.cfm?c_id=82&objectid=10445968

"Using a single crystal of silicon-28 grown by Russian and German
scientists over three years, a team of Sydney scientists and engineers
will grind and polish two silvery balls, each weighing precisely one
kilogram, with imperfections of less than 35 millionths of a millimeter"

All very clever and nice but I don't understand why if -

"The aim is not to change the value of the kilogram, but to ensure its
stability for all future times," Giardini said. "It will no longer depend
on an actual physical object and this is going to allow us to relate the
mass to the individual atoms."

and

"On completion, the spheres will be measured for volume in Australia,
Germany and Japan, then measured for mass. Belgian scientists will
look at the molar mass of the crystal used to calculate the number of
molecules in each sphere."

they can't work out how many molecules without building them. And
how are they weighing them ? Why isn't *that* the standard ?

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