3 ms·

No. The base unit with regard to notation/prefixes is definitely the gram. This question of whether there's a meaningful send in which the base unit is the ki

No. The base unit with regard to notation/prefixes is definitely the gram. This question of whether there's a meaningful send in which the base unit is the kilogram and not the gram really confuses people and I don't know what the answer is. People eagerly proclaim (a) it has something to do with French historical convention (but, they admit when pressed, this gives it no non-trivial meaning today) or (b) it has to do with the size of the actual reference weight in France (which doesn't make sense because the second was never an object, and a meter no longer is represented by an object yet we still call it a base unit). The only non-trivial interpretation I've heard (although it is still silly) is that the kilogram is the base unit in the sense that adding "kilo" to gram makes the derived units like the Newton the simplest. (You could define a Newton in terms of grams and, say, kilometers and seconds, or meters and milliseconds, but this would end up disturbing the other derived units even worse.) But of course, this is just a statement about the derived units.

oldcynic 9y ago
No, the SI base unit of mass is the kilogram. From the NPL: http://www.npl.co.uk/reference/measurement-units/ http://www.npl.co.uk/reference/measurement-units/ "The kilogram is the International System of Units (SI) unit for mass. It is the only remaining base unit to be defined by a physical object. All standards of mass must ultimately be traceable to this one object, a cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures (BIPM) in France"
- Cyph0n 9y ago
  NIST is working on a new reference for the kilogram based on Planck's constant, so that quote may become invalid in the near future.
  - oldcynic 9y ago
    NPL invented the Kibble balance that is being used in the proposed redefinition[0]. They discuss it and the Avagadro project on the page. So indeed it won't be valid much longer! [0] http://www.npl.co.uk/educate-explore/kibble-balance/ http://www.npl.co.uk/educate-explore/kibble-balance/
- jessriedel 9y ago
  The entire point of my comment is to note that "the SI base unit is the kilogram and not the gram" appears to be a contentless statement which is repeated mindlessly by people. And you responded by just repeating the statement that someone else made. If the President issues a statement that says "the base unit of the US is the furlong", but nothing else about the US or its system of measurements changes, this is a contentless statement. If someone else asks "but what does it actually mean for the furlong, as opposed to the inch, to be the base unit?", pointing them to the President's statement does not help. (Remember, saying "the kilogram is the base unit" cannot refer to the fact that the mass object in France weighs a kilogram, not a gram, because people also say "the meter and the second are base units", neither of which are physically instantiated anywhere.)
  - kjs3 9y ago
    From the link (since you didn't read it): "Formally agreed by the 11th General Conference on Weights and Measures (CGPM) in 1960, the SI is at the centre of all modern science and technology." And: "The seven SI base units, which comprise: ... The kilogram (kg) - unit of measurement of mass" It is factually the definition, and the fact you don't like it is completely irrelevant. The fact no one has explained it to your satisfaction is similarly irrelevant.

oldcynic 9y ago

No, the SI base unit of mass is the kilogram. From the NPL: http://www.npl.co.uk/reference/measurement-units/ http://www.npl.co.uk/reference/measurement-units/ "The kilogram is the International System of Units (SI) unit for mass. It is the only remaining base unit to be defined by a physical object. All standards of mass must ultimately be traceable to this one object, a cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures (BIPM) in France"

Cyph0n 9y ago
NIST is working on a new reference for the kilogram based on Planck's constant, so that quote may become invalid in the near future.
- oldcynic 9y ago
  NPL invented the Kibble balance that is being used in the proposed redefinition[0]. They discuss it and the Avagadro project on the page. So indeed it won't be valid much longer! [0] http://www.npl.co.uk/educate-explore/kibble-balance/ http://www.npl.co.uk/educate-explore/kibble-balance/
jessriedel 9y ago
The entire point of my comment is to note that "the SI base unit is the kilogram and not the gram" appears to be a contentless statement which is repeated mindlessly by people. And you responded by just repeating the statement that someone else made. If the President issues a statement that says "the base unit of the US is the furlong", but nothing else about the US or its system of measurements changes, this is a contentless statement. If someone else asks "but what does it actually mean for the furlong, as opposed to the inch, to be the base unit?", pointing them to the President's statement does not help. (Remember, saying "the kilogram is the base unit" cannot refer to the fact that the mass object in France weighs a kilogram, not a gram, because people also say "the meter and the second are base units", neither of which are physically instantiated anywhere.)
- kjs3 9y ago
  From the link (since you didn't read it): "Formally agreed by the 11th General Conference on Weights and Measures (CGPM) in 1960, the SI is at the centre of all modern science and technology." And: "The seven SI base units, which comprise: ... The kilogram (kg) - unit of measurement of mass" It is factually the definition, and the fact you don't like it is completely irrelevant. The fact no one has explained it to your satisfaction is similarly irrelevant.