REDEFINITION
of the KILOGRAM by 2011
For more than a century the world's fundamental unit
of mass has been based on a single, cylindrical piece of
metal. And authorized copies of it stored in secured
chambers around the world including the United States,
over the years in infinitesimal ways, are shedding or
accumulating atoms here and there, thus throwing off the
accuracy of the objects meant to be the world standard
for measurements of mass.
The 4 cm tall ingot of platinum and iridium, known as
the International Prototype Kilogram, offered the world
a standardized way of measuring what earlier scientists
defined as 1 kilogram being the mass (weight) of 1 liter
of distilled water (at sea level).
But to ensure greater accuracy there is a method of nano-measurement
using "Watt Balance" housed at the U.S.
National Institute for Standards and Technology (NIST)
near Washington, DC, which is a bid to recast the
kilogram as a mathematical equation, unerring, immutable
and ultimately easy for experts to reproduce. And it is
expected to yield groundbreaking calculations ahead of
an international deadline to produce a new definition of
the kilogram at the 2011 General Conference on Weights
and Measures in Paris.
The ultimate purpose of the "Watt Balance" is
to help scientists generate a reliable calculation of
Planck's Constant. A universal value that quantifies the
relationship between energy, light and an object's mass,
which in turn will produce a new, more accurate basis
for defining the kilogram worldwide.
The race to reinvent the unit of measurement before 2011
is considered important, partly because the kilogram is
the only holdout in the metric system still based on a
physical object rather than a formula derived from a
universal constant.
The meter, once pegged to the length of a bar of platinum was
redefined in 1983 by a formula using the speed of light. |
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