Carl Sorenson wrote in USMA 24091:
>In the U.S., Mg would be guaranteed to be confused with mg.  Many
>of you are concerned about confusion from overly precise package labels,
but
>this would be a much more serious confusion.

Joe wrote:
>I think think the danger is infinitesimal.
>       1 000 000 000 mg = 1 Mg

The danger of confusion would certainly not be infinitesimal!  Confusion
would be near-universal.

The problem would not be miscomprehension, but a total lack of
comprehension.  If a newspaper article had the quantity 10 Mg, the vast
majority of the public (at least in the U.S., and probably most places)
would either have no idea what it meant or they would think it was saying 10
milligrams.  If they thought it was saying milligrams but the context would
indicate tons, they would assume that it was some blatant typo.  Either way
they get no information from the text.  I doubt I would have had the
slightest comprehension of it last spring.

I'm much more interested in getting metric to become mainstream in the U.S.
than with leaving the mainstream of metric usage.  Which would get a better
response: trying to get a person to use a unit that 95% of the world uses,
or one that 1% of the world uses?  As I said before, if it is hard to get
the U.S. to adopt the metric system, it would be much harder to reform the
system as it is used by most of the world.  I wouldn't start with the U.S.,
either.

I think the ton is an entirely useful unit, anyway, especially when dealing
with large quantities.  I would rather deal with gigatons than petagrams.
With the latter, you have ridiculously large numbers of absurdly small
grams.  Using tons evens it some.

Actually, when measuring truly monstrous quantities, such as planetary or
stellar mass, I generally see numbers of kilograms expressed in scientific
notation (e.g., ten to the power of 31).  This has the advantage of using a
single unit in all quantities; the numbers are compared by looking at the
exponent.  The other common thing is measuring in solar masses--this allows
easy comparison between stars.

I wonder if anyone has ever confused petagram with pentagram...

Carl


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