Talk:International System of Units/Archives/09/2019

2019 Updates and Base Units

With the 2019 definitions of the units based on natural constants, the kilogram and ampere can no longer be described as base units. The kilogram needs to be replaced by the joule as one of the base units. Planck's constant has the units of joule seconds. The second is defined from the cesium atom definition. Thus a fixed value of Plank's constant defines the joule. From the joule and the definition of the metre, we define the newton. From the definition of the newton, the metre and the second, we define the kilogram. The newton and the kilogram are thus derived units.

The fixed value of the elemental charge defines the coulomb. Thus the coulomb is the base unit and from the coulomb and the second, we define the ampere. Thus the ampere becomes a defined unit.

In the definition of the kelvin, the equation J = kg⋅m^2⋅s^−2 needs to be replaced by definition of the joule as derived from Plank's constant. Ametrica (talk) 02:49, 29 September 2019 (UTC)

@Ametrica: can you show some reliable sources that support your arguments, or are they your original research? -- DeFacto (talk). 09:33, 29 September 2019 (UTC)

The unstated premise of Ametrica's argument seems to be a definition of "base unit" as being the first-defined unit to quantify a new dimension in the system (not one even one that is independent of other unit definitions). However, as the lead of Base unit (measurement) should make clear, a base unit is nothing of the sort. It is simply a unit chosen by convention in a particular way. The SI 9th brochure, which is the authoritative source for the SI redefinition, is clear about which units are the base units. —Quondum 18:54, 29 September 2019 (UTC)