Lionel Elie Mamane wrote:
On Tue, Jul 03, 2007 at 06:25:33PM +0200, Anders Breindahl wrote:Also, the metric system (and to a larger extent, the SI system) has an arbitrary _base_ unit (ever heard of the one-meter-bar in Paris?).Incidentally, that is not the reference anymore. The meter is the distance that light crosses in absolute vacuum in 1/299,792,458s.
Oh... and *that's* not arbitrary? :POriginally, it was 1/40,000,000th of the earth's circumference or something like that. But the earth jiggles, so they had to switch to something that holds still. :)
Well, back in my Physics classes, they said that it was "defined" as the the mass of 1 cubic decimeter of water at 4-degrees Celsius (when water is most-dense)... which is also a milliliter. That lump in France is probably because it's so much more stable than a jug of water (ie, evaporation, etc).I believe that the kilogram is still defined by "the mass of that lump of metal in Sèvres (near Paris, France)".
- Joe
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