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From: sa209@utb.shv.hb.se (Claes Andersson)
Subject: Re: "What is Life?"
Message-ID: <1995Feb6.125045.15753@gdunix.gd.chalmers.se>
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References: <1995Jan26.153830.4455@gdunix.gd.chalmers.se> <3gbhj1$klg@engnews2.Eng.Sun.COM> <1995Feb1.193052.16719@gdunix.gd.chalmers.se> <3guf5d$26h@engnews2.Eng.Sun.COM>
Date: Mon, 6 Feb 1995 19:09:26 GMT
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holtz@netcord.Eng.Sun.COM (Brian Holtz) wrote:
>In article <1995Feb1.193052.16719@gdunix.gd.chalmers.se>,
>Claes Andersson <sa209@utb.shv.hb.se> wrote:
>
>>The reason why: Tornadoes, crystals etc. doesn't maintain their
>>entropy. A tornado exist because it rotates rapidly.
>
>A tree exists because it stands still in the sunshine.

But this is totally irrelevant. Of course life must be able to make a
series of assumptions about its environment. The important thing is
that a dead tree can stand in as much sunlike as it pleases, fungi, micro
organisms etc. will use it to contribute to their own entropy sinking
mechanism.

But you are right in one respect, it exists because it stands still in the
sunshine. A rock will fall apart virtually unaffected by if it stands in
the sunshine or not.

>
>>If it had actively
>>added energy to the system to keep up the windspeed, it would
>>had been alife but it doesn't.
>
>If a tree had actively shone sunlight on itself to keep up its
>metabolism, it would be alive but it doesn't.  ["actively?  Why is
>activity necessary?  Viruses are not active.]

It actively transforms the sunlight and glukos into energy. It would
have been a perpetual machine if it would transform one form of
energy (1) to another (2) just to supply itself with the first form (1).

>>A fire is itself a shift of entropy between the wood (for example) to
>>the surrounding air.
>
>A tree is itself a shift of entropy between the sun to the surrounding
>air.

Yes but it do not actively makes sure that it occurs in places with a good
energy supply. A tree uses some of its energy to make sure that its sperms
gets to whatever place that is of an advantage. This can be done via the
generation of fruits which is eaten by animals and carried off to another
place or by little parachutes, propellers etc. etc. Do you see any strategy
that a fire use to spread to the right place?

>
>>When the energy it is supplied with is finished,
>>(the life expectancy of that particular fire) it dies.
>
>When the sunlight a tree is supplied with is finished, it dies.

Of course, without energy it cannot exist. However, trees are very
rarely exposed to this threat and therefor they haven't evolved a
strategy to deal with it. Suns don't go out every other day, so to say.
>
>>If it tried to find
>>more wood to burn, it too would had been alive.
>
>Fire "tries" just as hard to find combustibles as trees do to find
>sunlight.   [Intention is best left out of these things.]

No it don't. Refer to what I wrote earlier in the post.

>
>This entropy definition seems far too inclusive to be a useful
>definition of life.  When you try to edit out the false positives, you
>quickly lose things like trees.

As I've stated - No I don't. Trees are exellent examples of this sort of
mechanisms. They use the energy to build a phenotype that can tranform
one form of energy to another and it actively search new places by
growing in different directions (Try to put a plant with a lightsource that
it has to bend to reach and you'll find that it has a strategy to grow in
that direction and this is not due to a one-step process like oxidation.)
and the design of its sperms.

Claes Andersson. University of Bors. Sweden
