Newsgroups: comp.ai.alife
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From: sa209@utb.shv.hb.se (Claes Andersson)
Subject: Re: "What is Life?"
Message-ID: <1995Feb9.233556.29536@gdunix.gd.chalmers.se>
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References: <1995Feb1.193052.16719@gdunix.gd.chalmers.se> <3guf5d$26h@engnews2.Eng.Sun.COM> <1995Feb6.125045.15753@gdunix.gd.chalmers.se> <3h6676$btc@engnews2.Eng.Sun.COM>
Date: Fri, 10 Feb 1995 05:55:13 GMT
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holtz@netcord.Eng.Sun.COM (Brian Holtz) wrote:
>In article <1995Feb6.133515.18880@gdunix.gd.chalmers.se>,
>Claes Andersson <sa209@utb.shv.hb.se> wrote:
>
>>Do you suggest that there are lifeforms that aren't alive?
>
>I don't know what you mean by "lifeform".  Maybe it will help if I
>say: a lone terrestrial virus on an outbound spaceprobe becomes
>effectively dead upon the destruction of all other terrestrial life.

  Say that some earthlife back in time travelled forward and met this
dead virus? You never know do you.. But I see you point. Well, I
wish to identify the process of life. This definition would also say
that a rabbit on an outbound spaceprobe would die when this
happened as well.. It cannot reproduce by itself either. And I
cannot agree on that.


>>As soon as you find a lifeform that isn't evolved (not that I think there
>>are any) it will be falsified.
>
>Definitions are not really falsifiable.  What you really mean is that
>we will have an urge to call this unevolved vivacious thing alive but
>our definition won't let us.  As I explained to another poster, I'm
>pretty confident that such an entity can't exist in this universe.

 Yes you are pretty confident according to what we see and know
here.. but I agree, I don't believe that there is any such beast.

>
>>A general simple rule like
>>that one I'm advocating is on the other hand not possible to falsify
>
>Except that it includes tornados as alive, and so is found unworkable
>from the start...

 Well, I'll come to that later in the text. But you surely know the
difference between an inductive and a deductive evidence. And
that inductive evidences cannot be global. You can say that such
a deifnition with reproduction etc. does with great certainity apply
to all lifeforms on earth and is likely to apply to other lifeforms
as well but you can never define life with it.

>
>In article <1995Feb6.125045.15753@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.
>>
>>[...]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.
>
>So?  You tried to make some point about how a tree can "maintain" but
>a tornado cannot.  I replied that the only distinction is that you
>have pre-decided to call trees alive but not tornados.  You replied
>with this discussion of decay.  Do tornados not decay?  Is decay upon
>death a new requirement for life?

 Decay upon death is, in our universe, soemthing that we can take
for granted. Life postpones this dacay (increase of entropy) longer
than the actual mix of material normally would last.

 I have no predecided. I only think it is amazing that you refuse to
see that a tornado lack any form of entropy sinking mechanism and
that trees don't. A tornado may have a low-entropy but it does in
no way transform energy to stay that way. Such transformation of
energy is something that evolution has made possible bacause of
that evolution is very good at creating complex systems.

>
>>[A tree] actively transforms the sunlight and glukos into energy.
>
>A tornado actively transforms atmospheric temparture gradients into
>wind.  Please define "actively".
>
>>>>A fire is itself a shift of entropy between [...]
>>>
>>>A tree is itself a shift of entropy between [...]
>>
>>[fires] do not actively makes sure that it occurs in places with a good
>>energy supply. [...] This can be done via the
>>generation of fruits [...] little parachutes, propellers etc. etc.
>>Do you see any strategy that a fire use to spread to the right place?
>
>Fires send out embers on the same air currents that trees use to float
>seeds.  In fact, fires sometimes _create_ those air currents, which is
>a trick that trees cannot perform.  Sure, some trees put their seeds
>in fruit, but there are many one-celled organisms that do absolutely
>nothing to choose where to spread.  Are they not alive?

 Don't you see what's wrong in what you just wrote? It is a difference
and this difference is due to an evolutionary process (as I've said
it would work just as well even if it just materialized by chance but
that's very unlikely). Some trees put their seeds in fruits, no fires
fires would ever do that.

 But it really is just an effect of the definition, it has nothing to do
with it.

>
>>>>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.
>
>And so dies another would-be distinction between fires and trees...

No way. As I said... Of course life must be able to "make assumptions"
about its environment. There is a fundamental difference. Nothing in
the material of the tree implies a certain form of behavior. If you look
at some petrol, you'll be able to draw a straight line between the
stimuli (a match) and the behaviour (oxidation). The behaviour is
then a property of the material.

>
>>>>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.
>
>1. Yes it does.
>2. If "trying" is part of your definition, then your definition is
>   not very useful, because trying is about intention, and intention is
>   very subjective.

I will explain this further down. I don't mean any intent and it would
be totally meaningless if we are not allowed to look upon the process
that petrol burns if ignited and that a bee flies to a flower as different
types of processes. They naturally are. It is not only that the bee's
reaction is a longer chain, it's also that there is no path between
stimuli and reaction as it is between the match and the petrol and
that it ignites.

>
>>>When you try to edit out the false positives, you
>>>quickly lose things like trees.
>>
>>Trees are exellent examples of this sort of mechanisms.
>
>As are fires.  When you throw out fires on the basis of arbitrary
>notions of "actively" and "tries", you have no reason not to throw out
>trees except for your a priori decision that trees are alive.
>
>>They use the energy to build a phenotype that can tranform
>>one form of energy to another
>
>Is "building a phenotype" a new part of the definition?  If so, then
>you lose viruses.  Is the entropy now required to be thermodynamic
>entropy?  If so, then you lose all possible electronic life.

 No, the definition is still the same. I don't build a mastodontic
inductive definitiot like some other people here have done.
I don't lose electronic life at all. Do you think that, if you create
artificial life, the memory locations an artificial lifeform is on
will be alive? No.. that is not the case. A tree contains dead
tissue but is still considered to be a lifeform isn't it. I assume
that you have hair, yet you consier yourself as alive...

 But.. you actually have a point. Artificial lifeforms can very
well live in a universe that isn't subject to the laws of thermo-
dynamics but entropy will even then exist in some way.. information
of great complexity can also be considered to have a low
entropy (the isn't something I invented self, it is an accepted
part of information science). But the definition I propose applies
to our universum.


>
>>and it actively search new places by
>>growing in different directions
>
>Fires grow in different directions.

Well, I suppose you know the difference between why a tree grows
in a different direction and why a fires does it.
The material of the tree has nothing in it that implies that it should
behave like it does - There is, however, in the fire and in the fire's
fuel. There is nothing between the environment and the response.

>
>>and the design of its sperms.
>
>"Active", "tries", and now "design".  All intentional.

 Well, let me tell you something. Human language have always
had a hard time to dress evolutionary thinking in word. It sounds
intentional. I am not one of those who think that a molecule has
an intention. I'll explain what I mean:
ACTIVE : Not the direct result of anything.
              (Active: A person being thirsty, it goes and drinks a glass of water
	Not active : A tornado whirls around. Nothing else could have happened, just
	                  as simple as that a pencil falls if you drop it.)
TRIES : Has to do with the above.
DESIGN : Evolutionary formed.

Does that clear things up?

>
>>(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.)
>
>"Active", "tries", "design", "strategy".
>
>What's wrong with one-step processes?  How many steps are required to
>qualify as life?

 It requires many types of processes as it is a matter of transforming a
relatively "cheap" energy form into another form that is used for
keeping it in its original state. How many? I don't know but one
process could hardly do it. But if it could, it's ok for me.


