21 lines
1.2 KiB
Plaintext
21 lines
1.2 KiB
Plaintext
platinum-iridium
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adj. Standard, against which all others of the same category are measured.
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Usage: silly. The notion is that one of whatever it is has actually been
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cast in platinum-iridium alloy and placed in the vault beside the Standard
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Kilogram at the International Bureau of Weights and Measures near Paris.
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(From 1889 to 1960, the meter was defined to be the distance between two
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scratches in a platinum-iridium bar kept in that same vault this replaced an
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earlier definition as 10 -7 times the distance between the North Pole and
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the Equator along a meridian through Paris; unfortunately, this had been
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based on an inexact value of the circumference of the Earth. From 1960 to
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1984 it was defined to be 1650763.73 wavelengths of the orange-red line of
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krypton-86 propagating in a vacuum. It is now defined as the length of the
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path traveled by light in a vacuum in the time interval of 1/299,792,458 of
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a second. The kilogram is now the only unit of measure officially defined in
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terms of a unique artifact. But this will have to change; in 2003 it was
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revealed that the reference kilogram has been shedding mass over time, and
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is down by 50 micrograms.) This garbage-collection algorithm has been tested
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against the platinum-iridium cons cell in Paris. Compare golden.
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