Newsgroups: comp.ai.alife
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From: trin0008@sable.ox.ac.uk (Rick Heylen)
Subject: Re: "What is Life?"
Message-ID: <1995Feb24.012740.3158@inca.comlab.ox.ac.uk>
Organization: Oxford University, England
References: <1995Feb6.125045.15753@gdunix.gd.chalmers.se> <1995Feb9.233556.29536@gdunix.gd.chalmers.se> <3hgnqt$lk3@engnews2.Eng.Sun.COM> <1995Feb16.180714.11488@gdunix.gd.chalmers.se>
Date: Fri, 24 Feb 95 01:27:39 GMT
Lines: 217

Why not actually read this.. It does contain some new ideas I think.
Near the bottom are the most interesting parts however. 

In article <1995Feb16.180714.11488@gdunix.gd.chalmers.se>,
Claes Andersson <sa209@utb.shv.hb.se> wrote:
>
> No they don't. Could you please tell me in which way a tornado is anything
>else than the result of a certian meteorological condition.

Tornados 'metabolise' the warm moist air at ground level. A large storm 
effectively creates a pipe to the cold dry upper layers of the atmosphere
a mile or so up. When the warm moist air enters the area of extreme low 
pressure that exists in a tornado, the water vapour in the warm moist air
condenses and releases the latant heat of fusion of the water. This is a 
HUGE amount of heat energy. The 'steam' inside the vortex rises as it is much 
less dense than the surrounding air and gets spewed out of the top of the cloud
after cooling adiabatically. The 'steam' inside the vortex is the reason why
tornados are visible. 
An elementary thermodynamic calculation would show that the materials inside
the tornado itself are much more disordered than those outside. There is a 
large entropy change for the gasses as they enter the vortex. It is this 
entropy change that drives the movement of air that makes up a tornado.

> Tornadoes arise
>as soon as these conditions are present and the tornado as such is therefor
>not distinguisable from its environment, it's just a part of the phenomenon.

You're on the right track as tornados arise when the initial conditions are 
sufficient and don't require a seed provided by other tornados for a new one
to be born. However the same thing applies to viruses. 
A famous experiment documented in Stryer's Biochemistry illustrated how
viable viruses were formed out of their constituent bits. In the case of this
virus a T4 phage the bits were a solution of 'legs', a solution of 'heads'
a solution of 'body rings' and so on. Each of these body parts could probably
be sysnthesised from the elements if one so wished and the T4 phage self 
assembles as soon as the conditions are right. Presumably the necessary
conditions are introducing the solutions at the appropriate concentrations 
in the correct order.
Therefore T4 phages as well as tornados self assemble when the necessary
conditions are present.

>It get its energy, without transforming it, from the wind that is caused by
>differences in heat etc. etc.

As outlined above, tornados are very efficient converters of energy. They
convert random thermal energy and the energy of a supercritical vapour into
vast amounts of kenetic energy.

> It's a very automatic process that can be 
>expected to be found anywhere there is an atmosphere. Mars for example.
> I don't say that this disqualify it as a lifeform but the fact that it 
>doesn't transform energy in any way, doesn't actively maintain its entropy,
> disqualifies it.

From a thermodynamic standpoint the phrase 'doesn't actively maintain its
entropy' contains no meaning whatsoever. It *does* contain the word entropy
which presumably impresses people until a real physicist/chemist comes along
and debunks it.

> Not the same thing and you know it. The tree transform one sort of
>energy into another that allows it to take incredibly complex forms.
>A tornado is propelled by the wind and nothing further happens, just
>what could be expected by any non-living thing.

Hand-waving nonsense. 
Imagine you understood enough about the world and the laws
of physics to be able to predict reality down to the motions of atoms. 
It's a thought experiment so don't start telling me about the uncertainty
principle. Imagine that you had a computer which stored *all* the information
about all the molecules in (lets say) and amoeba and you had the real organic 
amoeba in a jar next door. Now you simulate the passage of time for the amoeba
and of course time passes normally for the real amoeba. Imagine you can run the
simulation faster than the real time so you can predict accurately what the
amoeba will do etc. Which amoeba is alive? If you understand entirely how
something functions then is it still alive? Just beause something has complex
behaviour doesn't mean to say it's alive.

>>No dead tree is identical to a living tree.  The difference between
>>them is, in terms of entropy maintenance, the same as the difference
>>between a tornado and a recently-dispersed tornado.
>
> No, your'e right. Not really. But remove just one little piece of its
>function so it cannot metabolize anymore. There is no such thing
>that can be done with a tornado? 

Remove the source of warm moist air? Remove the non-inertial frame of reference
(that's the coriolis force to you and me).
Remove the latant heat of vapourisation of water or remove the pipe to the
upper atmosphere. Do any of those and the tornado will die.

> Perhaps everything is alive? Obviously, everything isn't alive...

More to the point, is anything alive? 
'Living' 'life' and 'alive' are all very emotive words and we all have an
instictive idea of how to use them when taking about objects or behaviour.
Nature of course doesn't give a brass farthing about the words we use. The
laws of phisics are just the same for everything ( I was tempted to say 
living and non-living things).
When talking about the behaviour of living things we anthropomorphowhatsit
their behaviour and say 'The plant grows towards the light because it needs
the light to synthesise sugars.' This is obvious drivel. It is simplifying
maters to the extreme. The plant grows towards the light because the 
chemistry and mechanics behind plant growth says that it has to. The reason
why the behaviour of phototropism is universal amongst plants is that plants
with this behaviour reproduce into more plants with the same behaviour than 
plants similar in every other way except they lack phototropic behaviour.

It would be helpful if people would divorce the behaviour and the mechanism
behind the behaviour from the reason for the behaviour's existance.
The behaviour is based on pure physics, chemistry and biology. The reason
for the behaviour is explained by the revised Darwinian theory of evolution.
If yuo look closely at the discussion you see that it's a somewhat disguised
rehash of the vitalism idea. That somehow 'living' things have something that
'non-living' things lack and that there's a distinct line between the haves
and have-nots. 
All phenomena can be analysed in terms of the phenomenon itself and the reason
for the existance of the phenomenon itself. 

>the question becomes quite bizarre.. there is a difference between
>a tree and a tornado.

There is a difference between a tree and a tornado but there's also a 
difference between a tornado and a rock , a tree and a rabbit, a rock and a 
rabbit, a tornado and a rabbit , a tree and a rock. To my mind, from a 
rigorous scientific viewpoint, there's no useful sensible common factor
between the tree and the rabbit , the rock and the tornado.

> Do it? I mean directly after that they dies. In the moment of death.
>It is from then you can compare what happens to the system when it
>is alive and when it is dead.

From a scientific viewpoint (and for similar reasons) there's no consistent
rule for deciding whether something's alive/dead/dying/born etc.

> What I was after was the fact that viruses, just like cars, are designed
>(viruses are evolutionary designed, and cars by humans) to stay in
>the shape they are. They don't have any mechanisms for it. I don't
>have to mention entropy but since it points out very well what I'm after
>it would be stupid not to.

This bit about "Metabolism is the means by which 'living' things keep their
structure intact." is a real red herring. For you to be able to have a 
structure you need to be able to distinguish the structure from the rest of the
environment. This is possible as the structure has a lower entropy than it's
environment. If this structure was created from the disordered environment 
it must have had, at some stage, a period where the entropy of the environment
was increasing to drive a local reduction of entropy which brought about the
organisation of the local environment to form the structure. 
To summarise:
If you have a structure, you must have had a local reduction in entropy to form
that structure.
Since discrete things have a structure, you also need a local reduction in 
entropy to form them. Structures commonly regarded as 'living' such as cats
have a metabolism in order to grow and when not 'growing' they metabolise 
to avoid the dissolution of their structure. When they 'die' this structure
maintainance mechanism no longer functions and hence they decay in various 
ways. However structures commonly regarded as 'non-living' also exhibit this
behaviour. When a diamond grows, it metabolises a small amount of gravitational
potential energy (of the lava above it, diamonds are more dense than carbon)
and some of the random thermal energy of the lava ( diamonds are formed 
endothermically). This metabolism continues and the diamond grows. When removed
from the high pressure, high temperature environment the diamond decays (albeit
slowly). Hence the diamond dies when removed from the lava environment.

Similarly, consider a tree. When the sun shines on the tree, it metabolises
the sunlight in order to produce more celulose and generally maintain itself
from deacy. When the sunlight doesn't shine on the tree, the tree actually
decays. When we eat, we metabolise part of the environment (the food) and 
our entropy decreases. When we are not digesting our bodies decay.
Essentially, the obviously worn bits are replaced at the expense of other
less obvioulsy lost bits. For instance the keratin in your skin is replenished
from stocks of protein source-material located elsewhere in your body.
If you run a marathon or starve, some of your muscle mass is metabolised to 
maintain more important structures (and also to provide energy).

Perhaps one can have a working rigorous definition of a living thing as
'A structure that stops it's local entropy from increasing.'
We would have some very odd members of the 'living' class
A tree is living when the sun shines on it but dying when it doesn not.
Humans die when they're not eating!	-That's a funny one!
Diamonds die when they're no longer in a high temperature high pressure
environment.

There's one more problem however.
Observant readers will have realised that I said that a tornado has a higher
local entropy than the surrounding atmosphere. This is possible as the
atmosphere is in a high energy state (hotter air below cooler air). The
tornado is a mechanism by which these layers can be reversed or mixed.
We can therefore say that the atmosphere is a living thing which metabolises
sunlight (and a small amount of geothermal energy). One mechanism for
the death (ie entropy increase) of the atmosphere is a tornado.
The tornado is the absence of the lack of disorder that is the atmosphere.
The funny thing about tornados is that they're not so much a structure
as defined previously but more like an absence of structure made possible
as the rest of the environment (the atmosphere) is so ordered. The absence
of structure (the tornado) appears to be a distinct thing as it contrasts
with the rest of the environment which is structured (the atmosphere).
Similarly fire and flames have a higher entropy than the rest of the 
environment (the fuel) hence they are a means by which the structured 
environement of the fuel can become more disordered. 
The fuel is already dying (becoming less ordered) but the presence of
a flame makes the disordering (dying) process more rapid. 

>of what certain words means. With "Actively" I don't mean everything
>that the word can mean, I mean that there is a sort of mechanism that
>manage to maintain the entropy so that it distinguishes the lifeform from
>its environment. Therefor, in our environment, simple mechanisms like
>atmospherical currents etc. etc. can't be accepted as life qualifiers.
>If a tornado occured in vacuum and wandered about despite the fact
>that it normally wouldn't be able to, then it would
>perhaps quilify it as a lifeform.

That's silly. If you sir can occur in an environment which demands the complete
absence of the element carbon and you still post to newsgroups then you would
perhaps qualify as a lifeform. 
That's silly. For a lifeform to be judged as alive by your deffinition, you 
have to let it strut it's stuff in an environment which it survives in.
