Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site ski.UUCP
Path: utzoo!watmath!clyde!cbosgd!ihnp4!zehntel!dual!ptsfa!politik!ski!jmm
From: jmm@ski.UUCP (Joel M. Miller)
Newsgroups: net.cooks,net.flame
Subject: Re: Truth in Advertising?
Message-ID: <138@ski.UUCP>
Date: Sun, 18-Nov-84 23:55:15 EST
Article-I.D.: ski.138
Posted: Sun Nov 18 23:55:15 1984
Date-Received: Fri, 23-Nov-84 06:15:06 EST
References: <2559@dartvax.UUCP>, <642@watdcsu.UUCP> <216@pyuxt.UUCP>
Organization: Smith-Kettlewell Institute, S.F., CA.
Lines: 21

> >I still can't believe the ignorance prevailing in journalism today!
> >For someone to draw the conclusion that since black cars get hot in
> >the sun, then black pots must radiate lots of waste heat is
> >incredulous!  This person should have at least consulted a basic
> >physics text.
> 
> >On the other hand, an object of colour x can only radiate light (read:
> >heat) of colour x (i.e. that wavelength).  Therefore, a 100% black pot
> >will radiate *no heat* at all.  It will be warm to the touch, though.

As I recall from high school physics, good absorbers of heat are good
radiators (& vice versa).  Imagine a universe containing a box.
Eventually this system will reach thermal equilibrium and the box &
its surroundings will be the same temperature (2nd law of thermodynamics).
But what if the surface of the box made it a good radiator and, at the
same time, a poor absorber?  Then more heat would leave the box than
would enter, and you could make a killing in the frozen food business
with this no-cost (no energy cost, specifically) refrigerator.
Similarly, if the surface of the box were a better absorber than a
radiator, it would spontaneously heat up, I suppose, until the rest of
the universe was at absolute zero.  No thanks!