Okay...the basics will stay the same: a kilometer will still equal 1,000 meters, but the definitions of the most basic units are under scrutiny and a new global initiative to revise these is underway.
The NIST has backed the movement to update the definitions of seven base units of measurment: the second (time), the meter (length), the kilogram (mass), the ampere (electric current), the kelvin (thermodynamic temperature), the mole (amount of substance) and the candela (luminous intensity).
The proposal aims to base the new unit definitions on modern definitions and scientific constants (i.e.: Planck and Boltzmann) discovered since the original definitions were created.
For example, the kilogram is based on the weight of a platinum-iridium cylinder kept in a vault at the International Bureau of Weights and Measures in France (see pic above). This cylinder was created 130 years ago, and, as we now know, materials break-down and degrade over time, so this cylinder weighs less than it initially did. The proposal aims to base the kilogram on a formula based on Planck's constant, removing this variability.
Read the full article at the NIST Web site here: http://www.nist.gov/pml/wmd/20101026_si.cfm
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