The kilo is losing weight, changing all of science, but unfortunately we don’t know why

[Archean]

Good news, dieters! The kilo is losing weight, changing all of science, but unfortunately we don’t know why

Deep below Paris, in a vault that can only be opened by the simultaneous turning of three keys held by three different people, is the international prototype kilogram — the kilo against which all other kilos are based. The kilo is the last SI unit that is still defined by a physical artifact, rather than a constant of nature, but four of the seven SI units are fundamentally underpinned by the kilogram, making the international prototype extremely important… And yet worryingly, the international prototype is losing weight, changing science as we know it, and no one knows why.

 

[bobcat]

Perhaps we should abandon the unreliable prototype and go back to the original definition of the kilogram as the mass of one liter (10x10x10cm cube) of water at 4 degrees Celcius.

Unless the meter, or specific density or water, or degree Celcius also change.

 

[cliffordcooley]

The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram.
A kilogram isn't what it used to be. Literally. The original name for it was the 'grave', proposed in 1793 but it fell victim to the French Revolution like its creator, Lavoisier. So begins the tale of the most unusual SI unit. The kilogram is the only base unit with a prefix in its name, and the only one still defined by a physical artifact, the international prototype kilogram or IPK.

But the problem with this definition has long been apparent. The IPK doesn't seem to maintain its mass compared to 40 similar cylinders minted at the same time. The goal is therefore to eliminate the kilogram's dependence on a physical object. Two main approaches are being considered to achieve this end: the Avogadro Project and the Watt Balance.

<snip>

 

[St1ckM4n]

Yeah, I heard it could be because of gravity warping the weight.