[boost] Temperature/kelvins Aren't Special

From: Daryle Walker (darylew_at_[hidden])
Date: 2004-01-19 04:12:41

I think a previous post ("Re: [boost] Re: Units libraries... (long reply)"
by Phil Richards) gave me the impression that the poster thought temperature
should get special treatment within an unit/dimension library.  I don't
think it should.

Temperature is a physical quality like length and mass in that a negative
value makes no sense (in "normal" life physics, not some potential weird
quantum and/or cosmological theory).  And addition of two values or the
scalar multiplying of a single value work the same in all three cases.  The
"solution" of using relative values for temperatures is misleading because
length and mass have the same "problem"!

It could seem that temperature doesn't have these mathematical properties
like length and mass, but there's some historical (mis)conceptions.

1.  Unlike length and mass, there was no obvious truly-zero temperature.
2.  In fact, it's only been in the past couple of centuries that scientists
realized that the concept of an "absolute zero" could exist.  (The others
have been observationally obvious since pre-history.)
3.  It's been more recently in human history that temperatures close to
absolute zero have be found or generated.  (This lack of personal
observation is possibly what lead to [2].)

Where do Celsius (a.k.a. Centigrade) and Fahrenheit fit in?

Since no one traditionally knew about absolute zero, people made up relative
scales, each with an arbitrary "zero point".  These scales would have an
offset when translated to a regular unit/dimension scale.  This offset makes
the traditional temperature scales unsuitable for regular scientific
computation.  The solution would be to translate to/from a "normal" scale.

DISCALIMER: I'm just guessimating this from stuff I tried to remember from
high school/college.  So if physicist and/or historian thinks I'm way off,
feel free to correct.

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT hotmail DOT com