Guy Hoelzer  wrote in
news:cfdfd7$2tc6$1{at}darwin.ediacara.org: 

> in article cfas1m$22dt$1{at}darwin.ediacara.org, Tim Tyler at
> tim{at}tt1lock.org wrote on 8/10/04 9:10 AM:
> 
>> Guy Hoelzer  wrote or quoted:
>>> Tim Tyler at tim{at}tt1lock.org wrote on 8/8/04 3:22 PM:
>> 
>>>> However the definition *needs* to say something about the evolution
>>>> being "non-trivial".  Else we have flames and
crystals to contend
>>>> with once again.
>>> 
>>> Crystals are easy to do away with because their dynamics have
>>> already died. The definition of life ought to at least imply that
>>> life is inherently dynamic.
>> 
>> Crystals have dynamic qualities.  In particular they grow and break
>> up. 
>> 
>> In many respects I classify crystals as a *lot* more life-like than
>> flames - since there's a more obvious and capable mechanism for
>> transimtting information between generations with crystals.
>> 
>> Crystals do template copying - and each layer of crystals inherits
>> information from preceding layers.
>> 
>> This can be seen in two main areas - the inherited cross-section in
>> "needle-like" crystals:
>> [e.g.: http://originoflife.net/information/graphics/kaolinite.png]
>> ...and also in inherited repeat patterns in layer crystals such as
>> 
>> barium ferites and biotite micas - where layer repeat patterns of
>> over 100 layers in thickness have been observed - indicating
>> transmission of information through considerable thickness of
>> crystal. 
> 
> You have focused more on the dynamic process of crystallization,
> rather than on crystals themselves, which is perfectly appropriate
> IMHO.  Bone formation is essentially a crystallization process and
> very much like other living processes, as you point out.  My point was
> that crystals themselves are like the skeleton of a corpse.  They are
> the remnant pattern of a dynamic process of self-organization.  I do
> see your point, however, about the importance of existing in a "holy
> adaptive landscape", to use the language of Kauffman or Gavrilets. 
> Simple landscapes, like those for most crystallizing systems, don't
> allow evolution because the system just falls into a deep, stable 
> structural pit. 
> 
> Do you know much about liquid crystals?  They are more "glassy" than
> solid crystals and seem to overcome at least some of these issues.
>  
>>> Flames are tougher, I think.  The logical distinction between fire
>>> and life leads me to think of Bak's edge of chaos idea, a viewpoint
>>> that I would not argue for in its entirety.  Fire is pure chaos.  It
>>> cannot evolve because it cannot live long enough in the
>>> deterministic realm to build a useful memory of its past.  Fires can
>>> grow, but they don't really develop in the sense that an organism
>>> develops.  I think that life requires a more conservative 
>>> (deterministic) sort of inertia. 
>> 
>> Flames too have an inheritance mechanism.  However perhaps not very
>> much is inherited.  Small flames tend to give rise to other small
>> flames. blue flames tend to give rise to other blue flames - and so
>> on. 
>>
>> Much of the inheritance is environmental in nature.  One common
>> reason flames give rise to other similar flames is because they are
>> likely to be buring the same fuel.
> 
> Right.  I usually think of the fuel as something extrinsic to the
> system so, for example, I would argue that the temporal consistency of
> flame qualities represent an external memory (inheritance) rather than
> a mechanism of inheritance inherent to the flames. Are you arguing to
> include fuel within the bounds of the system?
>  
>> Even raindrops have inheritance - when they split their offspring
>> definitely share a number of their qualities.
>> 
>> My preferred metric for dealing with such things involves the
>> quantity of heritable information involved.  I would dismiss
>> prospective organisms with not very much heritable information as not
>> /really/ being alive. 
> 
> AMOUNT of something seems like a pretty tenuous way to distinguish
> natural categories (e.g., living vs. non-living).  How much is enough?


I think the definition of life has to encompass the use of fuel, but it 
should be something like "the ability to maintain a structure against an 
energy gradient by using an available energy source." This gets around 
the crystal question because their structure is the lowest energy 
solution, not a structure maintained against a gradient. Flames utilize 
an energy source but do not maintain a structure. Tornados might qualify 
as alive under this definition - I don't really know whether their 
structure is a lowest energy solution but I suspect it is not. The 
definition could be qualified further by requiring the use of electron 
transport for energy - I hesitate to do this because it might eliminate 
non-earth life that should still qualify. But perhaps electron transport 
is in fact a requirement for any true life?


Yours,

Bill Morse
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