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One good site
MDN
Nelson Minar
Blog licensed under a Creative Commons License
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The kilogram is shrinking;
one part in twenty million lost in 115 years. The problem is that of the
seven standard
units, the kilogram alone is still defined in terms of a physical
object rather than a fundamental scientific relationship.
meter
kilogram
second
There are
several options
for redefining the kilogram in a nicer way, including deriving
from measuring
Planck's constant with a
Watt balance
or measuring Avogadro's number with a perfectly round
silicon crystal.
ampere kelvin mole candela |
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