Text 754, 145 rader
Skriven 2004-11-10 21:40:00 av Tinyurl.Com/uh3t (1:278/230)
Ärende: Re: First Mutation Was Bi
=================================


> From: an588@freenet.carleton.ca (Catherine Woodgold)
> I should reword it to something like "sets up, before it
> disintegrates, the conditions to create a copy of itself ..."

Yeah, that sounds just about right.

> The resources might have been very limited:  a small, steady
> supply of RNA bases from a specific source, allowing a few
> hundred RNA strands to exist at a time in a local vicinity
> (and none of any importance elsewhere).  Um, a geological formation
> that attracted lightning or a volcanic vent or something.

Prior to the first replicator growing to fill the oceans and produce
*huge* quantities of whatever that replicator's specific reaction
products are, I don't believe any complex chemical, RNA or whatever,
anything beyond what the Urey-Miller experiments already produced,
would be produced in huge quantities. Also I don't believe that some
special physical characteristic of some local area would cause specific
production of such a complex chemical only in that particular place in
the absense of an already-existing replicator.

Now *if* there was already a replicator, and if some local area had
something special about it, such as a large deposit of some particular
metal that was leaching out rapidly, and if that metal's presence
caused a variation of the replicator's activity such that it produced
some other reaction product, not what it produces everywhere else, then
I can believe something complicated like RNA might be produced in large
quantities in that locale but not elsewhere.

> Also, I think whatever was the food of the replicator could
> also have been food of things that weren't replicators at
> all -- just ordinary chemical reactions.

I already answered that point: For a long time before the first
successful replicator chanced into existance, there were simple
chemicals being broken apart and ionized, causing cascades of chemical
reactions, producing large yield of a few chemical species and
producing single molecules of a very large variety of chemical species.
Also chemicals were randomly breaking down, due to being unstable
already and jiggled by random thermal motion, or due to bumping into
some other chemical that reacts with them. Over time, an equilibrium
was reached among all but the rarest molecules, whereby the production
and destruction of each molecular species were equal, and a statistical
equilibrium was reached among the rarely-created molecules, whereby a
static random model of their existance would adequately explain them.

It's in that equilbrium mix of chemicals where the the first successful
replicator chances into existance, whereby that equilibrium mix of
chemicals is sufficient for that replicator to exponentially increase
in number of copies. We've already accounted for anything that consumes
or destroys the food for this replicator in the equilibrium mix, and
the presumption is that in this equilibrium mix, with all the natural
consumption and destruction of replicator-food, there's still enough
replicator-food remaining to allow the replicator to exponentially
increase. If you start with equilibrium mix, add the replicator, and
then deduct natural destruction of replicator-food a second time,
you're making an accounting mistake of applying the same debit more
than once.

Note that before the first successful replicator grows to sufficient
quantity to consume a significant fraction of the equilibrium quantity
of replicator-food, no additional competition for that replicator-food is
going on beyond what was already happening in the equilibrium mix. All
sorts of natural processes (chemical reactions, breaking down) are
consuming replicator-food, at the same rate it's being produced, and
all these natural processes are competing with each other for that
replicator-food, but all these processes are balanced in equilibrium.
If you magically removed one way that replicator-food could be
consumed, the equilibrium quantity of replicator-food would increase,
and then all the other pathways would increase in rate in response to
that increase in supply. But no such magic would happen, except maybe
if some metal catalyst that was leaching out of a mineral deposit got
all finished leaching out. Likewise if a new pathway to consumption
appeared, the quantity of replicator-food would decrease, and all
pathwaysto consume it would decrease their rate in response to
decreased supply. Prior to the first replicator, this wouldn't happen
except if some new source of leaching of metal-ion catalyst appeared,
such as a new asteroid crash, or fracture in the crust exposing a
previously hidden mineral deposit. In either case, rates of consumption
would adjust to the new decreased or increased available, and a new
equilibrium would be established.

So with just a little bit of that first replicator, just a few billion
copies of it in some local area near where it first chanced into
existance, the equilibrium in the rest of the ocean would be the same
as before, but the equilibrium in the middle of the ball of replicator
would be shifted, where the replicator has consumed so much
replicator-food that the quantity is significantly reduced, lowering
the fecundity of the replicator to approximately 1 (instead of
significantly greater than one as was obtained in the original
equilibrium mix), and also due to diminished supply, the reaction rates
for all natural consumption of replicator-food would be reduced in that
local region.

In fact, in the center of the replicator ball, the quantity of
replicator-food in the water might be diminished so low that fecundity
of the replicator there is much less than one. This is because any new
replicator-food produced elsewhere and diffusing into the ball is
intercepted by further-out copies of the replicator, and consumed
there, before the replicator-food can diffuse all the way into the
center of the ball. So there might be a considerable die-off of the
replicator in the innermost parts of the ball. So as the replicator
ball grows, there's a particular sphere (approximately) where there's a
balance between replicator-food available and replicators ready to
gobble it, where the fecundity is exactly one, and inside that sphere
there's a shortage of food so replicators are dying off, and outside
that sphere there's still more than enough food so fecundity is greater
than one.

Eventually the replicator ball grows so large that some edge of it gets
close to the high-energy locale which is the starting point for the
cascades that produce replicator-food. The environment is too harsh
there, so replicators are destroyed more readily, and the cascades are
in their early stages before replicator-food has yet been produced, so
there's not enough replicator-food available, so replicators diffusing
in that direction die off, allowing replicator-food to reach the
interior of the ball, reviving the starved replicators that happened to
be there.

Now a new equilibrium is reached: Just about every bit of ocean, except
places too close to a high-energy source, have lots of copies of the
replicator in them. Whenever a molecule of replicator-food is created
by the chemical cascades from high-energy sources, there's a molecule
of replicator almost right there, ready to bump into it and consume it.
So virtually all the replicator-food gets consumed by the replicator
almost immediately after it's created, leaving almost none of it to be
consumed or destroyed by other processes. So approximately the same
quantity of replicator-food is produced as before the replicator
existed, but now it's being consumed almost entirely by the replicator
and hardly at all by any other process because all the other processes
are starved for this particular input. (OK, maybe the replicator isn't
quite *that* quick to gobble newly-formed replicator-food, so maybe
some of the replicator-food is destroyed so quickly that it never bumps
into a replicator molecule before it's gone already, so natural
destructive processes and replicators share the consumption of
replicator-food, both consuming significant quantities of it.)
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