22 lines
3.0 KiB
HTML
22 lines
3.0 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>platinum-iridium</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../P.html" title="P"/><link rel="previous" href="plan-file.html" title="plan file"/><link rel="next" href="playpen.html" title="playpen"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">platinum-iridium</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="plan-file.html">Prev</a> </td><th width="60%" align="center">P</th><td width="20%" align="right"> <a accesskey="n" href="playpen.html">Next</a></td></tr></table><hr/></div><dt><a id="platinum-iridium"/><dt xmlns="" id="platinum-iridium"><b>platinum-iridium</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">adj.</span></dt></dt><dd><p> Standard, against which all others of the same category are
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measured. Usage: silly. The notion is that one of whatever it is has
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actually been cast in platinum-iridium alloy and placed in the vault beside
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the Standard Kilogram at the International Bureau of Weights and Measures
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near Paris. (From 1889 to 1960, the meter was defined to be the distance
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between two scratches in a platinum-iridium bar kept in that same vault
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— this replaced an earlier definition as
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<tt class="literal">10<sup>-7</sup></tt> times the distance
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between the North Pole and the Equator along a meridian through Paris;
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unfortunately, this had been based on an inexact value of the circumference
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of the Earth. From 1960 to 1984 it was defined to be 1650763.73
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wavelengths of the orange-red line of krypton-86 propagating in a vacuum.
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It is now defined as the length of the path traveled by light in a vacuum
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in the time interval of 1/299,792,458 of a second. The kilogram is now the
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only unit of measure officially defined in terms of a unique artifact. But
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this will have to change; in 2003 it was revealed that the reference
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kilogram has been shedding mass over time, and is down by 50 micrograms.)
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“<span class="quote">This garbage-collection algorithm has been tested against the
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platinum-iridium cons cell in Paris.</span>” Compare
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