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. But this will have to change; in 2003 it was
revealed that the reference kilogram has been shedding mass over time, and
is down by 50 micrograms.) This garbage-collection algorithm has been tested
against the platinum-iridium cons cell in Paris. Compare golden.

