Kilogram's Future Hangs In The Balance

In one sentence they say the kilogram's been taken out only three times and then later they suggest it might have gotten lighter because of periodic washings. Looking at the picture of how the kg is kept I assume the latter sentence is nonsense.<p>Can someone explain this to me?

I thought that a kilogram was the mass of 1000 cubic centimeters of water at melting temperature, and that a centimeter is 1/100 of a meter which is the distance that light travels in a vacuum in the time it takes a caesium-133 atom to emit a little more than 30 periods of radiation (9,192,631,770 p/s / 299,792,458 m/s).

What is the problem with defining the kg in terms of the already existing atomic mass unit?<p>See <a href="http://en.wikipedia.org/wiki/Atomic_mass_unit" rel="nofollow">http://en.wikipedia.org/wiki/Atomic_mass_unit</a><p>The atomic mass unit is already associated with the mole, which is in SI.

From the article: "... around 50 micrograms (billionths of a kilogram)". Oh NPR -- I thought you were better than that :(<p>Edit: njm below is correct, i misread that as "billionths of a gram)". I rescind my above frowny face and apply it to myself :(

And I thought the kilogram was defined in some platonic, mathematical way relative to some well-known constant in the laws of physics all along...<p>Also, how did they decide "how much" the initial kilogram should weigh?

How do the Imperialists do it for the pound (lb)?

Good witty article titling, vibhavs. Its like Fark, but with substance.