From: henley@eng.auburn.edu (James Paul Henley)
Subject: Re: Thermodynamics FAQ
Organization: Auburn University Engineering
Date: Fri, 31 Jul 1992 15:23:04 GMT

In article <1992Jul31.071648.10927@murdoch.acc.Virginia.EDU> lfoard@Turing.ORG (Lawrence C. Foard) writes:
>In article <henley.920730124402@wilbur.eng.auburn.edu> henley@eng.auburn.edu (James Paul Henley) writes:
>>Actually, the entropy will have increased.  What happened is that the work
>>being done by the Sun was chemical.  That increased entropy is in the form
>>of chemical entropy.  If the plant does not grow, or reaches a state in
>>which it sheds leaves as fast as it grows new one, and there is sufficient
>>microbial activity to cause the leaves to decay as fast as they are being
>>shed, then you have reached steady state.  As long as you can complete the
>>biological food cycle, the system can continue to live.
>>
>>Try the following experiment:
>>
>>Take the same sealed container, surround it with artificial sunlight 24 hours
>>a day.  The second law of thermodynamics predicts that the plant will not
>>be able to survive - you will reach equilibrium, and all internal processes
>>will cease.  This should be easy enough to try. 
>
>The plant only needs a heat differential, light comes in at a high energy
>(equivalent to 1000K or so), and is then reradiated by the plant into the

That is why I specified that it was surrounded - a uniform radiation field
in.  I should have also specified that it was insulated against conductive
and convective heat transfer out - limited only to radiative heat transfer
out.  What would happen in that situation?

>air at room tempature. Only if the plant was as hot as the light source
>would there be a problem (and plants tend not to like 1000K) :-)
>
If the radiation in is uniform, you've got a *BIG* problem.  No differential.
>
>Try it you will be surprised :-)

As amended, I still stand by the prediction.  Any biologists want to prove
me wrong?  Should be very very easy.  Suspend a glass container inside
another glass container with a vacuum.  That should prevent conductive
heat transfer out.  Completely surround the plant with artificial sunlight
so that the intensity is uniform.  You can use any intensity you choose,
but it must be uniform.   See how long the plant lives.  It can
grow, but it cannot go through the O2 breathing night cycle, so it will 
always breath CO2.  Once the CO2 is gone,  finito.

Oh, You can put anything inside the container you want,  plants, animals,
microbes, or any device of any kind that you chose.  But that device can
not receive any external source of energy except the artificial sunlight.
You can even put mirrors to shield part of the system, or to selectively
reflect sunlight.  If that system can survive, you will have proven
that the laws of thermodynamics do not apply to biological systems.
(what would that mean?)

The system that I just described is known as a perpetual motion machine
of the second kind.  One of the statements of the second law is:
"A perpetual motion machine of the second kind is impossible"


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James P. Henley Jr.
Chemical Engineering Dept
Auburn University

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