:platinum-iridium: adj. Standard, against which all others of the
same category are measured. Usage: silly. The notion is that one
of whatever it is has actually been cast in platinum-iridium alloy
and placed in the vault beside the Standard Kilogram at the
International Bureau of Weights and Measures near Paris. (From
1889 to 1960, the meter was defined to be the distance between two
scratches in a platinum-iridium bar kept in that same vault --- this
replaced an earlier definition as 10^(-7) times the distance
between the North Pole and the Equator along a meridian through
Paris; unfortunately, this had been based on an inexact value of
the circumference of the Earth. From 1960 to 1984 it was defined
to be 1650763.73 wavelengths of the orange-red line of krypton-86
propagating in a vacuum. It is now defined as the length of the
path traveled by light in a vacuum in the time interval of
1/299,792,458 of a second. The kilogram is now the only unit of
measure officially defined in terms of a unique artifact.) "This
garbage-collection algorithm has been tested against the
platinum-iridium cons cell in Paris." Compare {golden}.
-- The AI Hackers Dictionary
