Units reform harks back to US president Jefferson

Poquoson, Virginia, USA.

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Regarding the new International System of Units definition for the kilogram, the kelvin, the ampere and the mole, you say that the “idea to base all units in relation to constants of nature — being unchanging and belonging to no one country — has been around since the late nineteenth century” (Nature 563, 451–452; 2018). In fact, science leader and former US president Thomas Jefferson suggested it in 1811.

In a letter to Robert Patterson, a mathematician at the University of Pennsylvania, Jefferson wrote that a standard unit “should be fixed by nature, invariable and accessible to all nations, independantly [sic] of others” (; see also I. B. Cohen Science and the Founding Fathers, 1995).

Nature 565, 567 (2019)

doi: 10.1038/d41586-019-00326-3

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