[extropy-chat] FWD (SK) Heisenberg's Uncertainty Principle

[scerir]

> Can anyone here give me a 
> good layman's explanation 
> of Heisenberg's uncertainty principle?
> Jonathan

If you write the word "uncertainty"
here http://www.arxiv.org/find/quant-ph
(in the "Title" field) you'll see
how this topic is controversial.

A well known somebody also writes that
uncertainty relations have little to
do with QM 
http://www.arxiv.org/abs/quant-ph/0403038

Anyway the Uncertainty Principle states that given 
a pair of canonically conjugate variables (the associated 
operators do not commute) or, by extension, a pair of 
Hermitian operators, the product of the uncertainties 
of the conjugate variables must exceed a certain small 
number (in general Planck's constant divided by
4 pi), ie
-position and momentum
-energy and time
-a field and its rate of change
-x-component vs. y-component of angular momentum
-3-metric and extrinsic curvature K
-entropy and temperature
-pressure and volume
-chemical potential and moles

Deutsch, then Ghirardi, etc. developed a theory
of "entropic" uncertainty relations.
They are much better than usual uncertainty
relations, which are meaningless in certain
cases, ie with "bounded" observables 
http://www.arxiv.org/abs/quant-ph/0310120
or "time-energy"relation unless you define 
a very special "time" (not a pure parameter) 
http://www.arxiv.org/abs/quant-ph/9906030
http://www.arxiv.org/abs/quant-ph/0110004
 
Kevin Brown writes good pages here
http://mathpages.com/home/kmath158.htm
http://mathpages.com/home/kmath488/kmath488.htm