Ampere Could Be Redefined After Experiments Track Single Electrons Crossing Chip

Posted by timothy on Tuesday January 14, 2014 @05:53AM from the micro-management dept.

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."

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Re:Condescend much? by UnknownSoldier · 2014-01-14 07:23 · Score: 4, Interesting

I'll probably get down modded but it is not just the technologies but the basic definitions of the SI system are pretty fucked up.
There are numerous problems, the primary being:
* the seven SI base units are not independent
e.g. the Amp depends on the definition of the kilogram ?!?!
http://www1.bipm.org/en/si/si_constants.html#figure
Quoting Dr. Xavier with my emphasis added:
"If for instance, one had to change the definition of the Kg unit, we see that the fundamental units candela, mole, Amp and Kelvin would change as well. .. So one cannot say there are seven fundamental SI units if these units are not independent of each other. The other big fault is the obvious redundancy of units. Although not very well known to all of us, at least two of the seven base units of the SI system are officially known to be redundant, namely the mole and the candela. These two units have been dragging along, ending up in the SI system for no reason other than historic ones. "
* http://www.blazelabs.com/f-u-suconv.asp