The standard system of weights and measures is slowly advancing in its definition of official reference standards. From such things as the size of the King’s foot to the length of the forearm, the reference moved to platinum weights and bars. Now it is moving to universal constants of nature. Lubos has his take as
An SI vote next week may turn ℏ into a known constant.
The Science Magazine’s Adrian Cho has some fresh details: Metric system overhaul will dethrone the one, true kilogram
Most importantly, the 1-kilogram platinum-iridium alloy will be thrown away to the French sewerage system. Instead, one kilogram will be defined indirectly so that Planck’s constant will be h=6.62607015×10−34J⋅s exactly.
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For the normal people, nothing will change at all. The physical constants will have more or less the same values, within error margins that are narrower than the normal people may distinguish, and the SI units will have the same meaning as before. The reform will only affect the life of the experimenters who were capable of measuring the constants with the globally competitive precision. They will have to translate their measurements to the new units and realize that it’s different numbers than before that will inherit the relative error margins.
there’s more. go see.