"Uncle Al" wrote in message
...
Dieter Britz ,in ...
There used to be, at least, an October issue of some physics
journal (Physics Today?) in which there was an update on the
values of some physical constants. Which journal was that
please, and is it still doing that October issue? I am trying
to find out how the Avogrado constant can be measured to about
8-9 decimal plces, when it surely must involve weighing some
sample of matter.
Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.

[Al]
Current accepted value 6.0221415(10) x 10^23/mol,

http://physics.nist.gov./cgi-bin/cuu...s.x=78&All+val
ues.y=18
1998 CODATA, 6.02214199(47) x 10^23/mol
However, folks doing exceptionally accurate x-ray diffraction on
silicon (to replace the Pt-Ir kilogram artifact) get a different
value, ...............
Becker, P. et al. "Determination of the Avogadro constant via the
silicon route," Metrologia 40 271-287 (2003)
6.0221353 x 10^23/mol
PTB Standards Laboratory in Braunschweig, Germany thus gives number
which is way the Hell different.
http://www.ptb.de/en/index.html
Uncle Al

[hanson]
There seem to be more to Avogadro's constant, N_A, then is
normally portrayed about it in literature. These, N_A's unspoken
traits, may be one of the causes giving the problems that make it
difficult to nail down a very accurate numerical result for N_A.

It may have to do with the fact that all fundamental, physical
constants are ultimately compared to and expressed in/by the
(completely arbitrated/chosen/selected) metric system units,
AND... complicating that fact is that N_A is tied to other fundamental
physical constants such as h, c, and G, & so it is difficult to say which
is the most fundamental one. h & c have been measured to great
accuracy, but Newton's G is still problematic when it comes to the
accuracy of its numerical value. There are a few old (1930?)
relations/equations that may illuminate this accuracy-dependcency
problem, such as:

One mole of Planck time equals the atomic time unit:
tau / t_pl = a^(-1) * (N_A*pi*sqrt3)

or one mole of Planck length equals the H-Bohr radius or the
classical electron radius:
r_H / l_pl = a^(0) * (N_A*pi*sqrt3)
r_e / l_pl = a ^(2) * (N_A*pi*sqrt3)

or that one mole of electron masses equals the Planck mass
m_pl / m_e = a^(1) * (N_A*pi*sqrt3)

So, since all Planck units are combos of hbar, c & G, one can see
that there are, for instance, the following relationsships between
N_A and Newton's G, when re-expressing the above equations by
straight forward means and substituting the Planck units, *_pl,
with hbar, c, & G, as:

G * N_A^2 = [1/3] * [ hbar * c] / [pi* a* m_e]^2 = const
or equivalently:
G * N_A^2 = [2/(3pi)] * [c^3] * [r_H^2 / h] = const
or there are
others like, G * N_A^2 = f(tau, etc) = f(Lyman freq, etc) = const

These 2 lines loosely state or can be interpreted as to say that
the product of the gravitational mass attraction at the gigantic
mole-squared size level has something to do with or is equivalent
to expressing some gravitational event/state or phenomena seen
quantized (hbar) at the atomic level caused by EM effects.

It may be akin to something like k*N_A = R(gas) or e*N_A = F
where N_A couples the atomic domain of heat or electricity to/with
the everyday cgs/MKS mole sized experience in the respective fields.
Similarly, this G* N_A^2 product may be applicable/useful to estimate
gravitational effects on other then the levels/magnitudes/domains
where G is currently measured or tested at.

From/with these two equations we can concoct a further story, a
theory, for the accuracy issue at hand.
1) I leave it to the aficionado to make the numerical error analysis
with the right side (atomic realm) of these 2 equations.
2) the result of (1) gives the projected possible min. uncertainty
or max. accuracy spread of the product of G * N_A^2.
3) Being deep in the atomic domain here, where uncertainty
is the order of the day (according to heuristic paradigm)
we may have a demonstration and example of the HUP,
manifesting itself here in the uncertainty of either G or N_A
values.

If so, then only the unwieldy product of G * N_A^2 may be of
or may have a "fixed +/-" determinable numerical size/value,
but either one of each one, the N_A or G values alone, may only
be knowable in its accuracy at the expense of the accuracy of
the other one. ... Classic HUP gig??.....

However, since this product of G * N_A^2 is having the size
of ~ 10^40 cm^3/(gr*s^2*mol^2), I won't loose too much
sleep over it....unless some clever ****, or a dumb one by luck,
discovers a new amplification mechanism thru which this product
affects visibly/phenomenologically our macroworld and shows
up measurably in the games that are playing out in astronomy,
astrophysics or cosmology............will see! it would be rad!.......
ahahahaha...... ahahahahanson


ref: 11-avogadro-3