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Re: [uom-ontology-std] retitled: magnitude of a quantity

To: "uom-ontology-std" <uom-ontology-std@xxxxxxxxxxxxxxxx>
From: "ingvar_johansson" <ingvar.johansson@xxxxxxxxxxxxx>
Date: Thu, 16 Jul 2009 15:43:57 +0200 (CEST)
Message-id: <62709.83.254.147.78.1247751837.squirrel@xxxxxxxxxxxxxx>
Pat Hayes wrote:    (01)

> It always bothered me that dimensional analysis made angles
> dimensionless, when they are of such profound physical significance.    (02)

In the journal Metrologia, which is the main journal where topics relevant
for VIM and the SI system are discussed, this view has repeatedly but
unsuccessfully been argued for by Walter H. Emerson. See his three papers
"A reply to 'Definitions of the units radian, neper, bel and decibel' by I
M Mills et al.", Metrologia 39 (2002) 105-9; "One as a 'unit' in
expressing the magnitudes of quantities", Metrologia 41 (2004) L26-8; and
"On the algebra of quantities and their units", Metrologia 41 (2004)
L33-7.    (03)

I have the same view. See my home page Section 3: "Two Changes in the
International System of Units?"; I am very happy about all kinds of
comments on this paper.    (04)

> Clearly, direction of length matters. The fact is, 'length' should be
> treated as a vector rather than a scalar. This also, btw, helps with
> distinguishing length from width from height. BUt this is probably
> going too far out in left field for this forum :-)    (05)

You can't make it a choice either vector or scalar, since out of every
vector a scalar can be abstracted. Both the SI system and VIM consciously
restrict themselves to scalar quantities.    (06)

Best wishes,
Ingvar Johansson    (07)

-- 
home page: http://hem.passagen.se/ijohansson/index.html    (08)


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