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From: sa209@utb.shv.hb.se (Claes Andersson)
Subject: Re: "What is Life?"
Message-ID: <1995Feb1.193052.16719@gdunix.gd.chalmers.se>
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References: <1995Jan14.154408.20087@walter.cray.com> <davidovi-2001951930150001@aron210b.dorm.tulane.edu> <1995Jan26.153830.4455@gdunix.gd.chalmers.se> <3gbhj1$klg@engnews2.Eng.Sun.COM>
Date: Thu, 2 Feb 1995 01:49:04 GMT
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holtz@netcord.Eng.Sun.COM (Brian Holtz) wrote:
>In article <1995Jan26.153830.4455@gdunix.gd.chalmers.se>,
>Claes Andersson <sa209@utb.shv.hb.se> wrote:
>
>> I believe the simplest way of defining life is simply: "Something
>> that maintains a low entropy in an environment of high entropy."
>
>A tornado is alive?  I think not.
>
>Life is the ability to reproduce and evolve.  A more involved
>definition is required if we want to be able to tell living things
>from inanimate, unborn, and dead things.  An entity can be
>considered alive if and only if it 1) is of a kind that usually can
>reproduce and evolve, and 2) has achieved independence of a parent's
>direct, continuous, and non-fungible assistance to its environmental
>interactions, and 3) is able to reproduce or interact with its
>environment.
>
>Thus:
>
>- Lt. Cmdr. Data isn't alive.
>- Tornados and fires aren't alive.
>- Ideas aren't alive.
>- Sterile people aren't dead.
>- Comatose and brain-dead people aren't dead.
>- Viruses are alive.
>- A virus on an outbound space probe 'dies' if all other terran life dies.
>- Sperm are alive.
>- People flash-frozen alive are only provisionally considered dead.
>- Tierrans are alive.
>--
>Brian Holtz

 Well it feels like I'm repeating myself but anyway...
My definition (Not really mine, I read it somewhere but I can't
remember where.) is very short and don't include tornadoes.
The reason why: Tornadoes, crystals etc. doesn't maintain their
entropy. A tornado exist because it rotates rapidly. If it had actively
added energy to the system to keep up the windspeed, it would
had been alife but it doesn't.
A fire is itself a shift of entropy between the wood (for example) to
the surrounding air. When the energy it is supplied with is finished,
(the life expectancy of that particular fire) it dies. If it tried to find
more wood to burn, it too would had been alive.

Claes Andersson. University of Bors. Sweden
