Text 728, 159 rader
Skriven 2004-11-09 16:57:00 av Tomhendricks474 (1:278/230)
Ärende: Re: Metabolism Forced
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<< The same thing that powers the Miller-Urey type of experiments:
Molecules are ionized or torn apart by a high-energy source, either UV
or extreme heat (from volcanic activity, crashed meteor/comet, or
lightning). These start a cascade of subsequent chemical reactions with
anything they touch, with reactions near the start of the cascade
spontaneously happening almost immediatley, and reactions further from
the start having a slower reaction rate so they might sit in a
meta-stable condition for a relatively long time.

TH
Anything other than the sun would be random and would likely shut off as much
as produce more wouldn't it?.

> For those schooled in darwinian evolution - we stretch things to get
> to first replicator , because we understand the rest.

Well we consider the step from lots of interesting chemical activity in
those cascades of chemical reactions, to the first replicator, as the
only "missing link", 

TH
That is certainly enough of a problem to
stop any scenario so far.

everything else being pretty well worked out to or
confidence it'd really happen.

TH
I don't think it is at all - even if you have
a replicator - why would it need protein?
Where is the energy coming from?
What happens when the energy stops.
What environmental conditions would destroy
this? 
Where's the cells? and about a 100 more tough
questions.




 
> There is yet no reason why any aspect of life would have emerged on
> its own for any reason.

That sounds rather circular or redundant or somesuch. 

TH
There is only one realistic reason why anything would
independently replicate outside of the environment pressure - we want it to
happen in our scenarios -
wish fulfillment.
You can't avoid this tough question.



Per my
speculations, the first replicator didn't emerge for any reason other
than the fact the conditions suitable for formation of the first
replicator were present and enough time passed in that kind of
condition for the first replicator to chance into existance. 


TH
That's one of those magic wand reasons. A fluke
happens cause there is enough time for it.
But that doesn't happen. There is just as much
time when normal events happen, and their odds
are normal not astronomical.

See other post where I've listed all those.
They're like a get out of jail card - you use
it in your scenario when nothing else works.



The key
fact we don't yet know is the statistics (per unit time) of lengths of
chains (of once-through fecundity greater than one) of catalysts which
spontaneously appeared in the pre-life oceans. 

TH
This is the RNA world with one ribozyme.
It isn't enough.




Two other key facts
aren't personally known by me, but are probably known by somebody else:
The number of different kinds of catalyzed reactions, and the
statistics of chemical species in an equilibrium situation after a
Miller-Urey experiment has run long enough to reach equilibrium. As
soon as the length-of-chain statistics are learned, and that's put
together with the other two key items of info, we'll be able to
estimate how often capable replicators are spontaneously created, 



TH
How about how often they are systematically destroyed.
Do you think they are immune to destruction?


and
one more mathematical step (see my posting a few minutes ago in another
thread) takes us to the length of time to expect to wait before the
first capable replicator succeeds at surviving the first few tens of
generations to where there are so many copies of it that it won't go
extinct for a very long time, and only when replaced by a new species
of life derived from it.

TH
Again you have mutation that would destroy any
function within a few generations most likely.
Rember you
called for UV in the earlier part of the scenario.
The sun/uv is still there.



You haven't explained how a simple heat cycle could cause a wide
variety of chemical reactions to occur, whereby some replicator might
chance into existance eventually as a result of some random one of
those reactions. 

TH
Absolutely nothing is random. Every step is
forced by the sun/heat cycle. Life is what happens
on a planet where the sun shines down for a million
years or so under certain conditions.
There is no emerging of something outside the
environment. Life is that which the sun leaves.
It's just about that simple.
Life is the echo not the voice.






Has anybody ever run a Urey-Miller kind of experiment
where there is *no* input of ionizing or chemical-breaking-apart
energy, merely a smooth temperature cycling over a reasonable range
(say from near freezing of water to near boiling of water)? I predict
such an experiment could run for an indefinite time and still not
produce amino acids or anything else interesting. Do you disagree?

TH
The sun works fine in Miller - Urey type experiments.
The same results happen.
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