Mass

Decided: the lib ≈ 1.7714 kg, defined by fixing Planck's constant: h = 2;13 × 10^-28 exactly (lib × pace² / blink) - same method SI has used since 2019 CE. (= 2;13 × 10^-27 in lib × pace² / breath - same unit, just expressed per breath)

Why: fixing a constant is how SI defines mass since 2019 CE, so conversion is exact. The value of h was chosen so a cub of water ≈ 1 lib - the everyday rule of thumb matters more than a round constant.

Advantage: mass converts exactly to SI, and a cub of water still weighs about a lib.

  • The value of h was chosen so a cube of water 1 unc per side (1 cub) ≈ 1 lib
    • water at 20 °C: 0.9994 (better than SI's 1 L of water = 0.9982 kg at 20 °C)
  • Everyday rule of thumb works at every scale (1,728 (dec) = 1,000;):
    • 1 cub of water (12.1 cm side) ≈ 1 lib (1.77 kg)
    • 1 dig-cube of water (1.01 cm side) ≈ 1/1,000 lib (≈ 1.03 g)
  • 0;1 lib ≈ 147.6 g, 0;01 lib ≈ 12.3 g, 0;001 lib ≈ 1.025 g
  • Converts exactly to kg (h is exact in SI too)
  • Rejected:
    • Water itself as the definition: density depends on temperature, pressure, isotopes (SI dropped it for this reason)
    • 10^20 carbon-12 atoms (1.584 kg; 12^24 dec): nicely dozenal, but the dalton is not exact in SI
    • h = 2 × 10^-28 (1.864 kg): rounder h, but water cube only 0.95
  • Priority used: c round > water ≈ 1 > h round. Normal people use c-based length and water; almost nobody uses h directly.