To: WSFAlist at keithlynch.net
Date: Wed, 28 May 2003 00:12:08 -0400
Subject: [WSFA] reference kilogram slowly evaporating
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

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May 27, 2003
Science: Scientists Struggling to Make the Kilogram Right Again

NYT
By OTTO POHL

The kilogram is getting lighter, scientists say, sowing potential
confusion over a range of scientific endeavor.

Full Story:
http://www.nytimes.com/2003/05/27/science/27KILO.html?tntemail0

May 27, 2003
Scientists Struggling to Make the Kilogram Right Again
By OTTO POHL

RAUNSCHWEIG, Germany — In these girth-conscious times, even weight
itself has weight issues. The kilogram is getting lighter, scientists
say, sowing potential confusion over a range of scientific endeavor.

The kilogram is defined by a platinum-iridium cylinder, cast in England
in 1889. No one knows why it is shedding weight, at least in comparison
with other reference weights, but the change has spurred an
international search for a more stable definition.

"It's certainly not helpful to have a standard that keeps changing,"
says Peter Becker, a scientist at the Federal Standards Laboratory here,
an institution of 1,500 scientists dedicated entirely to improving the
ability to measure things precisely.

Even the apparent change of 50 micrograms in the kilogram — less than
the weight of a grain of salt — is enough to distort careful scientific
calculations.

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