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Ampere Could Be Redefined After Experiments Track Single Electrons Crossing Chip
ananyo writes "Physicists have tracked electrons crossing a semiconductor chip one at a time — an experiment that should at last enable a rational definition of the ampere, the unit of electrical current. At present, an ampere is defined as the amount of charge flowing per second through two infinitely long wires one meter apart, such that the wires attract each other with a force of 2×10^-7 newtons per meter of length. That definition, adopted in 1948 and based on a thought experiment that can at best be approximated in the laboratory, is clumsy — almost as much of an embarrassment as the definition of the kilogram, which relies on the fluctuating mass of a 125-year-old platinum-and-iridium cylinder stored at the International Bureau of Weights and Measures in Paris. The new approach, described in a paper posted onto the arXiv server on 19 December, would redefine the amp on the basis of e, a physical constant representing the charge of an electron."
Because a few atoms of the slug can sublimate into the surrounding atmosphere, even at room temperature. And because a few atoms of the surrounding atmosphere can adhere to the slug. And yes, at the precision we're talking about here, it makes a difference.
I guess I missed the humor tag in your original post.
That's OK. You were publicly correcting someone for the misuse of units of measure.
None of us expected you to have a functional sense of humor.
You never really know how close to the edge you can go until you fall off.
It is kept in air, but under bell jars. Way more than you ever wanted to know here...
http://en.wikipedia.org/wiki/Kilogram#Stability_of_the_international_prototype_kilogram
You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office