..... Stumper Index
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[i.e. your Knowledge Quotient]
Measure for Measure
Once upon a time, people were intimately connected with measurement of their world. A foot was the length of a foot, a leap was the distance an average person could leap and so forth. Admittedly, because feet and leaps and other such units varied from place to place this was a very imprecise method but it was human and, by and large, people understood both what they were measuring and the orders of magnitude they described using such terms.
As we move into the third millennium, everyday units of measurement have become less connected to our everyday lives. The French Revolutionary metric system which reigns almost supreme throughout the world is now mostly defined, as are the more modern SI units (Système International d'Unités), by basic concepts of theoretical physics that have little real meaning for most of us. The meter no longer has anything to do with a particular fraction of the Earth's circumference; it is defined as the distance traveled by light in a specific fraction of a second. The second itself has been redefined in terms of propagation of radiation, or periodicity of atomic quantal events.
Curiously, while most of the world measures distance in meters and kilometers, volume in liters, and mass in terms of grams and kilograms, the U.S. general public walks a mile, buys milk by the pint and apples by the pound. This can be a problem. In September 1999 when the Mars Climate Orbiter passed behind Mars and was not heard from again, NASA determined that the problem resulted from computer data entry of English instead of metric units, i.e. pounds instead of newtons.
But, to the question: there is a familiar metric, SI, unit upon which other units rely that has not - yet - succumbed to definition in terms of theoretical physics. The officially recognized world standard has rested for many years in a vault just outside Paris, France.
A) What is it?
B) What is it made of?
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