platinum-iridium

2 definitions found

platinum-iridium - Free On-line Dictionary of Computing (26 May 2007) :

  platinum-iridium
  
     <standard> A 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, as the bar defining the standard
     metre once was.
  
     "This garbage collection algorithm has been tested against
     the platinum-iridium cons cell in Paris."
  
     Compare golden.
  
     [Jargon File]
  
     (1997-02-20)
  

platinum-iridium - Jargon File (4.4.4, 14 Aug 2003) :

  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.