The International System of Units

The International Bureau of Weights and Measures defines metrology as "the science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology". The seven SI base units, the ampere, kelvin, second, metre, kilogram, candela and the mole are derived from seven invariant constants of nature. These are that,

  • The unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆νCs is 9 192 631 770 Hz 

  • The speed of light in vacuum c is 299 792 458 m/s 

  • The Planck constant h is 6.626 070 15 × 10−34 J s

  • The elementary charge e is 1.602 176 634 × 10−19 C 

  • The Boltzmann constant k is 1.380 649 × 10−23 J/K

  • The Avogadro constant NA is 6.022 140 76 × 1023 mol−1

  • The luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, is 683 lm/W


The nested scores in The SI Base Units use graphic images and text to chart the scale of the SI base units from micro to mega. This array of dimensionally independent yet interconnected scores demarcates a creative space between the precision in the field of metrology and the ambiguity of language; the invariant constants of nature with the evolving fringe of langauge.

Seven quotes by ... accompany the scores.

A realisation of metre by Patrick Farmer & David Lacey is available on... and a printed version is available form ... or to download here. 

Unknown Track - Unknown Artist

"...a spectacle and nothing strange a single hurt color and an arrangement in a system to pointing. All this and not ordinary, not unordered in not resembling."

Gertrude Stein