Re: [Phys-L] dimensional analysis

[John Denker <jsd@av8n.com>]

On 07/26/2012 01:40 PM, Larry Smith wrote:
> I'm not really trying to go anywhere with this except to understand
> why so many people use the term as a synonym for "unit conversion."
> If you do a web search for "dimensional analysis"  you will find lots
> of pages and YouTube videos where they will teach you unit
> conversion; most of them seem to be by HS Chemistry teachers or the
> URL is a college chemistry department.  The explanations I was
> _expecting_ to find seem to be from physicists.  Linguistically the
> term "dimensional analysis" seems to fit what the physicists on this
> list have said much better than "unit conversion."  While
> sociological explanations may not be needed to understand the scaling
> concept, curiosity is part of my nature.  I wonder why people use the
> words they do.

We agree that words are an entirely human construction, so if you are 
asking about words it is entirely sensible to look for sociological
explanations.

We agree that very commonly, this-or-that close-knit community has its
own argot.  Example:  Astronomers use the word "metals" in a way that
makes sense in context but would be insane in any other context.  Of
course the astronomers know this; no astronomer would argue that oxygen
is a "metal" in any terrestrial context.

The point I was trying to make yesteray, but did not state at all clearly,
is that sometimes it's argot, and sometimes it's just a mistake.  Yes,
the chemistry community can be amazingly cohesive and defensive about
some things, including some verrrry peculiar things, but I don't think
this is one of them.

A good way to find out about the consensus -- if any -- on terminology
in the chemistry community is to look at the IUPAC Gold Book.
  http://goldbook.iupac.org/index.html

Consensus terminology is documented there;  controversial stuff gets left
out.  When I look there, I don't get the impression that there is any
consensus on wrong notions of units versus dimensions.  Instead I get the
impression that nobody cared enough about the topic to think about it very
hard.
  http://goldbook.iupac.org/B00610.html
  http://goldbook.iupac.org/U06561.html
  http://goldbook.iupac.org/D01741.html

The super-important topic of scaling laws gets no respect at all.  Sigh.
  http://goldbook.iupac.org/search.py?search_text=scaling