Re: Is there a scientific definition of Fahrenheit, or not?


Randy Poe wrote:
Andy Resnick wrote:
DWIII wrote:
This is some minor issue that I have been wrestling with on my own for
some time now, and intensive web/newsgroup searching has come up empty.
Firstly I will go over the basics as I understand them.

<snip>

I'm not really sure what you are asking- First off, historically there
were many competing scales for temperature: Newton, Romer, Delisle,
Celsius, and Fahrenheit (among others). All used various
freezing/melting/boiling points of various forms of water, with varying
numbers of divisions between the two. Why Celsius and Fahrenheit's
became more widely used than anyone else's, I cannot say.

Kelvin and Rankine scales are absolute scales- they are thermodynamic
and have a proper conceptual foundation. The scales above, prior to
1860 or so were not, strictly speaking, well-defined measures of a
system (statistical mechanics provided the needed conceptual link
between energy and heat).

So I guess just as you reconcile the Kelin and Celsius scales, so you
can reconcile the Rankine and Fahrenheit scales. And Kelvin and Rankine
scales differ only in the energy interval corresponding to '1 degree'.

I think he's asking about that interval. Is a Kelvin exactly 1.8
degree Fahrenheit, or something slightly different? If
Fahrenheit is still defined as a scale where water freezes
a 32 deg and boils at 212 deg, but on the Celsius scale
those points are no longer 0 and 100, then the conversion
factor is no longer 1.8.

Nobosy will ever know, Since a Kelvin is defined
in terms of the triple point of H20.
So to define Kelvin, you have to defne water,
rather than temperature or degrees.







- Randy

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