I have no real problem with the phrase "looking at a temperature". I assume that
measurement equipment in general are artificial extensions of our senses, our
senses themselves are measurement equipment, so, in a colloquial usage, we are
still talking about measurement. (01)
As for the "direct" and "indirect" properties, I have seen nothing as yet that
makes me believe these distinctions are physical in nature, unless they really
are meant as "intensive" and "extensive" (I'm not convinced they are).
Some of the instances cited seem teleological: definitely not physical in
nature. I don't see "direct" and "indirect" as concepts within a UoM based on
SI/VIM. (02)
I do think that we must deal with representing uncertainty in measurement of
quantities.
I bring this up because Pat Hayes wrote: (03)
> I would strongly urge that we NOT do this, whatever the SI standard says; (04)
From an information science perspective, all decision processes have error
rates, i.e., uncertainties. Making measurements involves making decisions: the
metre-stick may be continuous, but the increment marks are discrete and I have
to decide what value to choose. (05)
From a scientific perspective, when we talk without any notion of uncertainty
about measurements of properties that are not observably discrete, we are
arguably talking nonsense. Even the counting of discrete properties is subject
to error. (06)
While it might not be common, everyday practice to explicitly refer to
uncertainty, it is usually tacitly assumed.
For example, when I ask for 1 kg of bologna at the grocery store, I'm pretty
sure they assume I don't mean 1.00 kg or 1.000 kg or 2 kg. (07)
It is certainly standard practice to cite uncertainty in communicating measured
quantities, and it's pretty well defined in the SI. (08)
R/Joe C. (09)
Ed Barkmeyer wrote:
> Gunther and Pat agreed on:
>>>> Either way, maximum allowable temperature and actual temperature are
>>>> both special kinds of temperatures.
>>>>
> Matthew West wrote:
>> MW: Then I ask you how I know when I look at a temperature whether it is a
>> maximum allowable one or not.
>>
>
> If you ever succeed in "looking at a temperature", tell us all how you did
> it. Temperature is a class/category of measurable physical phenomena. So to
> look at one, you have to pick a physical phenomenon to measure, and you
> should presumably know whether what you were measuring was an actual
> temperature or a "maximum allowable temperature". I would assume that you
> measured the latter as the last successful temperature measurement before the
> device exploded or imploded or turned into a pumpkin.
>
> In engineering practice, BTW, that is more or less what is done. You take a
> number of samples and expose them to increasing temperatures until they
> degenerate in some way. Then you assign the smallest such value (possibly
> with a safety factor) to the class as "maximum allowable temperature". But
> note that this stated value is not actually the measured value of a
> particular quantity. It is an "assigned property" -- a property that is
> accidental to a use or role or situation.
>
> I would argue that that property is a "use of a quantity", but it is not
> clearly a "quantity" in the sense of "particular quantity" or "measurable
> quantity". The "measurable quantity" with that name is the temperature at
> which that individual device actually fails, and you can only measure that by
> observing the failure. The "maximum allowable temperature" is (at best) an
> attribute whose value is a "quantity magnitude" -- an abstract "quantity", or
> more simple an attribute whose value is stated as a "quantity value".
>
> If this is the distinction between "direct" ("measurable") and "indirect"
> ("assigned"), I don't see how it is relevant to an ontology for units of
> measure, as distinct from some general ontology for uses of quantities and
> quantity values. "We only see that the missiles go up; where they come down
> is not our department." ;-)
>
> -Ed
> (010)
--
_______________________________
Joseph B. Collins, Ph.D.
Code 5583, Adv. Info. Tech.
Naval Research Laboratory
Washington, DC 20375
(202) 404-7041
(202) 767-1122 (fax)
B34, R221C
_______________________________ (011)
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