3 ms·

> It's probably the reason they punted and let a _kilo_gram be a base unit in the first place, Not quite - it's so that the system is coherent. https://en.wik

> It's probably the reason they punted and let a _kilo_gram be a base unit in the first place, Not quite - it's so that the system is coherent. https://en.wikipedia.org/wiki/Coherence_(units_of_measurement) https://en.wikipedia.org/wiki/Coherence_(units_of_measuremen... which makes a whole bunch of other things simpler. The other option to meter-kilogram-second would have been the centimetre-gram-second, but then you're not using the metre as your base unit for length. Scale is probably the reason for picking MKS over CGS, but it's only moving the weird-base-unit problem around. ISTR reading once that MKS has coherence advantages over CGS with regards to electromagnetism (probably current), but I can't find the reference now.

akira2501 4y ago
It's so that it retains coherence without moving to a non-gram based measurement. You could have easily selected a new unit, or even just given what we call a "kilogram" a non-prefixed name and be done with it. The point is, it's obvious that they didn't define the system on first principles, but allowed "creature comforts" to creep into the scope of the system. For example the needless definition of Hz which conflicts with radians, and the needless definition of the unitless mol. These are obvious conveniences. They're not first-class members of the system.