At 1 04 06, 10:21 AM, Bill Hooper wrote:
On 2006 Apr 1 , at 10:22 AM, Jim Elwell wrote:
... Table 3 of BIPM's SI document (Derived Units with Special Names)
Witness: klick for kilometer, nit for candela per square meter.
Perhaps my citing Table 3 was confusing, but that is where most
short names already reside: volt, watt, joule, etc.
The Table 3 Jim refers to above is not for ANY short names. It is
for DERIVED units only.
Bill, I haven't a clue what you are saying here. volt, joule, watt,
etc. are NAMES for derived units, and are labeled as such in Table 3.
They are also one syllable long. Therefore they are short names, and
most one-syllable names used in SI reside in Table 3.
SI tries mightily not to have more than one name for the same unit.
(There are exceptions like the litre for cubic decimetre, tonne for
megagram, hectare for square hectometre, etc. I think these three
may be the ONLY ones.) But to have two different names like klick
and kilometre for the same thing is exactly the kind of thing SI
seeks to avoid.
And here is the real point: people WILL invent/create short names for
any unit (base or derived) that is frequently used and is "too long."
You can't stop it. I can't stop it. BIPM cannot stop it. Legislation
cannot stop it. All the formal standards in the world cannot stop it.
So, is it going to occur entirely ad hoc, uncontrolled, in different
ways at different times and places?
Or will BIPM/CGPM assist in documenting and recommending such short
names so as to minimize their proliferation?
But to allow a new "short" name for a millimetre, for example, would
be a whole new class of units names. Now we are back to the Olde
Engish mixture of units (almost) with it's plethora of unnecessary
units names (and units).
Short names are not "allowed". They are created by people for
convenience. The SI standard can ignore or incorporate them, but it
cannot prevent them from being created and used.
However, I can imagine a move not to ADD extra names but simply to
REPLACE the long names by something shorter. Instead of having both
the klick and the kilometre for 1000 metres, why not make a new name
for the kilometre that BOTH
(a) is shorter, and
(b) follows a pattern of standard basic units and standard prefixes.
...
Unit basic names that are already only one syllable, would not change.
1 kilgram = 1000 grams
1 megwatt = 1000 kilwatts
1 meghertz = 1000 kilhertz
If the problem is really as serious as some of you think, then any
change you propose should keep the simplicity of the SI (or even
improve it), not just willy-nilly manufacture special names for
everybody's favorite long unit.
A system such as you propose makes a lot of sense, but I think (and
suspect you agree) that chances of the "real" names for units and
prefixes being changed are slim to none.
And it is the willy-nilly creation of names that WILL happen if BIPM
does not address the reality of the situation. And passing
resolutions deprecating short names is not addressing reality.
The candela per square metre noted by Jim is 7 syllables long. It
would become (perhaps) the cand per square met, a considerable
improvement at 4 syllables, but still long enough that an argument
can be made for giving it a special name like the "nit" or something.
As I pointed out before, to most people whether a name refers to a
compound unit or a base unit is immaterial. If it is too long, it
will get shortened. And now that a name such as "nit" is widely used,
there is no way it is going to be eliminated, even for a mere 4
syllable replacement.
Jim
Jim Elwell
[EMAIL PROTECTED]
801-466-8770
www.qsicorp.com
