On Aug 10, 2009, at 9:30 AM, David Leal wrote: (01)
> Dear Mike,
>
> I do not think that euro, dollar, yen, etc. should be within scope,
> any more
> than "6 inch wire nail", "10 X 150 galvanised coach bolt", etc..
>
> These are just classes of item of which you can have one or more. I
> can
> enter into a contract which says "on the 1st of October 2009 I will
> pay 1
> million euro into your account in Frankfurt, and on the 1st of April
> 2010
> you will pay 1.5 million dollars into my account in New York".
> Similarly I
> can enter into a contract which says "on the 1st of October 2009 I
> will
> deliver 100 thousand 6 inch wire nails to your site in Essen, and on
> the 1st
> April 2010 you will deliver 10 thousand 10 X 150 galvanised coach
> bolts to
> my site in Gary IN".
>
> Both are valid contracts. The notion that there is a kind of
> quantity called
> "value" which can be expressed in units of euro, dollar or "6 inch
> wire
> nail" is dubious and I think that we should keep well clear :). (02)
Well, let us just push on that for a moment. Economists and the entire
financial industry do seem to assume that there is something
underlying all fungible forms of exchange (that is, dollars and euros
but not 6 inch wire nails), something that they all measure and allows
them to be compared; and the notions of unit and scale seem to apply
here quite well also. Seems to me that while we should be careful,
that it may well be that some of our ontology will apply to currency
measures; and if it does, then there is no need to gratuitously
exclude this area of application. (03)
Pat Hayes (04)
>
> Best regard,
> David
>
> At 15:25 09/08/2009 +0100, you wrote:
>> ... and some of which rely on no physical laws at all, e.g.
>> currency units.
>>
>> Mike
>>
>> David Leal wrote:
>>> Dear Josh,
>>>
>>> I don't think that we disagree substantially. The kind of quantity
>>> "thermodynamic temperature" is defined by reference to a physical
>>> law. The
>>> Kelvin is defined by a physical law and by reference to an
>>> arbitrary fixed
>>> point - the triple point of water. However the ITS90 scale is not
>>> defined
>>> with respect to either a physical law or the Kelvin - it is an
>>> arbitrary
>>> scale which is defined by a measurement process and which has been
>>> shown by
>>> experiment to be close to the scale derived from Kelvin.
>>>
>>> I think we agree that the ontology needs to encompass different
>>> types of
>>> quantity, unit and scale - some of which rely upon illustrious
>>> physical laws
>>> and some of which rely upon rather weak ones. In the case of
>>> Rockwell C
>>> hardness, the "physical law" is very weak. It is merely that the
>>> values
>>> provided by the measurement procedure are consistent with one of the
>>> intuitive understandings of hardness - an ability to resist damage
>>> when
>>> impacted by a hard pointed object.
>>>
>>> Best regards,
>>> David
>>>
>>> At 16:54 07/08/2009 -0400, you wrote:
>>>
>>>> David,
>>>>
>>>> Temperature is not at all defined by the measurable processes you
>>>> mention. Those happen to be means of measuring temperature through
>>>> models which relate observable processes to a phenomenon of
>>>> interest,
>>>> namely temperature. The models may rest on more or less illustrious
>>>> theories, e.g. laws of thermodynamics versus concept of hardness in
>>>> material science. The scale or reference system for relating
>>>> coordinates to measurements within the model may be more or less
>>>> absolute in those theories, e.g. absolute zero versus spatial or
>>>> temporal coordinate systems. Nevertheless, I would contend that
>>>> they
>>>> are always present where units of measure are being employed
>>>> meaningfully (or should I say, realistically).
>>>>
>>>> Josh
>>>>
>>>> On Aug 7, 2009, at 4:32 PM, David Leal wrote:
>>>>
>>>>
>>>>> Temperature is not merely a
>>>>> phenomenon defined by the differential thermal expansion of
>>>>> mercury
>>>>> and
>>>>> glass or the behaviour of electrons in a thermocouple junctions,
>>>>> because we
>>>>> have the laws of thermodynamics.
>>>>>
>
> ============================================================
> David Leal
> CAESAR Systems Limited
> registered office: 29 Somertrees Avenue, Lee, London SE12 0BS
> registered in England no. 2422371
> tel: +44 (0)20 8857 1095
> mob: +44 (0)77 0702 6926
> e-mail: david.leal@xxxxxxxxxxxxxxxxxxx
> web site: http://www.caesarsystems.co.uk
> ============================================================
>
>
>
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> (05)
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