From: mrjg8679@uxa.cso.uiuc.edu (Michael R James)
Subject: Re: Thermodynamics FAQ
Organization: University of Illinois at Urbana
Date: Fri, 31 Jul 1992 17:05:32 GMT

henley@eng.auburn.edu (James Paul Henley) writes:

>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

Here I think we have the crux of our problem.  The plant in a
container of this sort will "see" a particular temperature
in the rate  that radiative heat is transferred in. So I
don't understand what exactly you mean when you say "any intensity
but it must be uniform". If you are emmiting radiation from 
a 1000K source uniformly then you will fry your plant.

>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?)
You will not grow anyhting, you will cook it.

>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.

--
 Michael James       mrjg8679@uxa.cso.uiuc.edu 

       barf  [ba:rf]  2.  "He suggested using FORTRAN, and everybody barfed."
            - From The Shogakukan DICTIONARY OF NEW ENGLISH (Second edition) 

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