The kilogram is shrinking; one part in twenty million lost in 115 years. The problem is that of the seven standard units, the kilogram alone is still defined in terms of a physical object rather than a fundamental scientific relationship.
meter kilogram second
ampere kelvin mole candela
There are several options for redefining the kilogram in a nicer way, including deriving from measuring Planck's constant with a Watt balance or measuring Avogadro's number with a perfectly round silicon crystal.
  2003-09-25 01:02 Z