World's roundest object - video

[mklotz]

Very good information as I was under the impression that they had already defined a kilogram in non physical terms.

They have, or at least are in the process of doing just that. The kilogram will ultimately be defined in terms of Planck's constant, 6.626E-34 joule-sec. When that work is complete and the definition is incorporated into the SI system, all of the basic standards of the metric system will be defined, not in terms of objects in a museum somewhere, but in terms of unchanging universal elements.*

An excellent everyman's explanation of this work is here...

https://www.vox.com/science-and-heal...weight-science

Yes, the kilogram will be defined in terms of a quantum mechanical constant. And so the Luddites who think the inferial pound is better will have to brace themselves for the inevitable since the pound is defined in terms of the kilogram. (1 lb = 0.453592 kg).

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* If Planck's constant, the speed of light, etc. ever evidence change, it will be necessary to completely rewrite all of physics. Given the success we've had building stuff based on our assumption that they are invariant, that's unlikely to happen.