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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."
A kilogram is straightforwardly defined as 2.20462 pounds. Simple enough.
I prefer rebel units. If you can't depend on Luke Skywalker for your calibrations, who can you trust?
Force was redefined in the prequels as midichlorians multiplied by anger. Conveniently it's kept the same equation:
f = ma
How about we change "At present, an ampere is defined as" to "Currently, an ampere is defined as"?
A duck.
Platinum and Iridium sublimate? Are you serious?
Sure it can. It just does it VERY slowly. The solid state is greatly preferred for these metals at room temperature, but at any temperature and pressure solid, liquid, and gas are all in equilibrium. When you're talking about thermodynamics and statistical mechanics, about the only absolute is zero, and that is a state that doesn't physically exist anywhere.
Then throw in quantum mechanics. There is probably some small but finite probability that I'll appear in your living room before I finish typ
The magnitude of many of the units comprising the SI system of measurement, including most of those used in the measurement of electricity and light, are highly dependent upon the stability of a 135-year-old, golf ball-size cylinder of metal stored in a vault in France.