William ChopsWestfield wrote:

> In the US, I suspect the failure to 'convert to the metric system' is
> largely due to the cost of converting the industrial infrastructure.

Hm... the US automotive industry converted to metric, quite some time ago=
,
I'm told. Probably about the same time they started to think about becomi=
ng
competitive and reducing cost (in the 70ies and 80ies).=20

The infrastructure seems to be there -- you can buy M3 screws just as
easily as you can by 4-40 screws. What seems not to be there is a general
consensus that it would make sense to use it...


> You have to convert ALL of that over.  And you'd probably have to keep
> all the old stuff as well, for repair an maintenance of older equipment.
> And since WW2, the US has had the largest industrial infrastructure in
> the world; with incredible momentum and probably nearly impossible (at
> least horribly expensive) to "convert" to anything.

I think by the time the conversion took place, that's what happened in mo=
st
other places. An infrastructure was in place, the old, inconsistent units
have been used in their respective markets, but people saw the advantage =
of
being able to talk to each other :)  The main difference, as I see it, is
that the USA is prolonging this intermediate state with multiple systems
for many decades now, over a century, as it seems inevitable that the US
industry will end up using metric (just like the US automotive industry).
I'm not sure that this is more cost effective. That sounds a lot like the
home owner who says he can't afford to fix the leak that costs him per
month twice in water costs of what the fix would cost...


> The best we could ever hope for is some horrible kludge hybrid of metri=
c
> and old units that would have few of the advantages attributed to metri=
c
> and ALL the conversion problems we had before plus new ones.

This is exactly what's happening now in the US. I think you should hope
(and shoot) higher... :)


> (Just imagine trying to change all your electronics designs from their
> 2.54mm pin spacing to 2.5mm pin spacing, for instance.)  Sigh.

There is an increasing number of metric spec'ed electronics parts. 0.8 mm
pitch, 0.65 mm pitch, 2 mm pitch etc. Many if not most newer cases are
spec'ed in metric units. Pretty much all cases that are spec'ed in
fractions of the King's toenails (I couldn't resist :) have also every
dimension given in mm in their specs. You don't have to change your desig=
ns
-- this seems one of the irrational thoughts that make this so difficult.
Just start to spec the new ones metric (128 mm x 68 mm instead of 5.04" x
2.68")... chances are that the majority of components on your boards are
spec'ed in metric unit by now anyway (if you use small SMT devices, at
least).

Ever wondered about some of the odd (in mil, that is) preferred drill siz=
es
that some board houses offer? Try converting these numbers to mm and you
see why :)


> (hmm. wouldn't it have been nice if the meter had been picked so that
> 1g=3D=3D10m/s^2 instead of that "tiny fraction of long distance" thing?=
)=20

The "tiny fraction of long distance" is long past; now it's based on the
speed of light and a time AFAIK. Basing it on the gravity acceleration of
the Earth would be a bit problematic, I think, as this is probably not ev=
en
in a well-defined place as constant as they want the meter to be. I'm not
sure, but probably the tidal movement alone already creates a disturbance
in the gravity acceleration that's above the precision they use for the
meter.


> You see this sort of paradox all the time.  "Modern" isn't what happens
> at the centers of innovation; they had to already be there to create
> that innovation in the first place, so they're already out-of-date.
> "Modern" is what happens when you HAVE the innovation and have to start
> building something from scratch=20

I'm not sure what you're talking about here. It sounds as if you're
insinuating that the industrialized countries that are metric now had it
somehow easier, picking up this innovation from the USA, where it was
invented, building their infrastructure on it. If it is that, this is not
true in pretty much all aspects.=20

The SI and its predecessors that it is based on (like CGS and MKSA) have
been developed at least as much in Europe as in the USA, if not more so.
The SI itself is definitely a European "invention". So the "center of the
innovation" was as much (or more) Europe as it was the USA.=20
Check out:

- CGS (proposed in 1830 by Gauss, later extended by Weber, Maxwell and
Thomson, all European). This is the first proposal of a consistent
measurement system.
http://en.wikipedia.org/wiki/Centimetre_gram_second_system_of_units

- Convention du M=E8tre: In 1875, 17 nations signed this treaty, among th=
em
the USA. http://en.wikipedia.org/wiki/Convention_du_M%C3%A8tre

- Between 1900 and 1940, Giorgi (another European) and others developed t=
he
MKSA system (meter, kilogram, second, ampere), that already resembled
closely the current SI. http://tinyurl.com/c9g4l

- Finally, in 1960 the current SI was introduced, based mainly on the MKS=
A
system, extending it in the same spirit and making its use consistent.
http://en.wikipedia.org/wiki/SI

As you can see, this was not a one-point-in-history thing; this was a
development that took over a century to culminate in the SI. During this
time most European countries (which had a quite developed infrastructure,
mind you, and were harboring most of the "inventors" of this system) slow=
ly
moved over their infrastructure according to the insight that this system
makes sense.=20

And then the "building from scratch" aspect also doesn't hold. Conversion
to metric happened in Europe mostly between 1850 and 1950 (roughly). I
don't think you can seriously claim that the USA was much more
industrialized than Europe in that period. All industrialized European
nations had an infrastructure similar to the US at the time. The effort t=
o
move to the metric system and to unify the various measurement systems in
use was not less than it would have been in the US -- at the time.=20

So, yes, in this context "modern" (the general use of the SI) is what
happens at the "center of innovation" (Europe, where this innovation has
been developed).

Gerhard

--=20
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