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}.

[glossary]
[Reference(s) to this entry by made by: {golden}]