Text 638, 121 rader
Skriven 2004-11-03 22:20:00 av Tinyurl.Com/uh3t (1:278/230)
Ärende: Re: First Mutation Was Bi
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> From: tomhendricks474@cs.com (TomHendricks474)
> the only real source of heat/uv/radiation was the sun.

Not correct. Most UV at Earth comes from the Sun, and did
during the early days, I'll agree. Also I'll agree most radiation overall
comes from the Sun, although in the early days there might have
been a significant amount of that other kind of radiation from short-lived
radioactive elements leftover from the Supernova that triggered the
collapse of our molecular cloud to form our planetary system and maybe
from other sources. But in the early days after Earth formed,
heat-of-formation of the Earth, actually produced more local heat than
arrived from the Sun. Over time the Earth settled down, falling of
heavy material toward the center decreased in rate as that material
became already there with no need to fall further, and later that heat
gradually escaped toward the surface. Meanwhile as the Sun's core
expanded, its rate of fusion at the surface of the core increased, and
the radiation from it increased. (It's still increasing, and in about
one more billion years it'll be too much for Earth to avoid all the
oceans boiling away.) Nowadays most of the heat at the surface of the
Earth is due to Solar radiation rather than geothermal energy, but in
the early days the balance wasn't yet shifted in that way and
geothermal energy dominated.

However only the UV is important for causing "interesting" chemical
changes which led to the first replicator, and I've already listed UV
as a possible source of such "interesting" chemistry, in addition to
geothermal vents and asteroid/comet crashes.

> Secondly no chemical system can adapt to a non cyclical heat source.

A simple replicator doesn't need to adapt. It just survives nicely.
So your point is moot.

> Thirdly thermal vents would not work for numerous reasons.

I await your argument in favor of that remark.

> 1. Energy available chart -
> Solar radiation 260,000.
> Now compare with electrical discharges, shock waves, radioactivity,
> volcanoes, and cosmic rays = 7.

Do undersea vents count as "volcanos" in that statement?

Most solar radiation is infrared, and most of the rest is visible
light. UV is a small fraction. IR and visible light don't directly
initiate chemical changes. When an IR or visible light photon strike a
chemical, most of the time it merely jiggles the atoms a bit, causing
them to wobble and/or rotate. This local motion is coupled to other
molecules, whereby the energy is shared. We measure these small random
motions as thermal energy. When enough thermal energy accumulates, a
state change occurs, solid to liquid to gas. Also most chemical
reactions run faster at higher temperatures. But in the absense of
anything to upset the equilibrium chemical mixture, no significant
chemical reactions occur. Evaporation of water from one location and
condensation at another location can cause some chemicals to become
more concentrated in one place than another, but there's nothing for
any of them to react against, so crystallization is the most
interesting thing that ever happens.

But a single UV photon directly breaks a chemical bond, creating an
unstable radical or ion or atom which tends to initiate new chemical
reactions with other chemicals it encounters. Likewise the very high
temperatures present in geothermal vents and in crashed
asteroids/comets cause changes beyond simple state change, gross
disruption of molecules to form active radicals/ions/atoms. In
conclusion it isn't the total amount of energy that's important for
this discussion, it's only the amount of UV radiation that reaches the
surface of the ocean and breaks chemical bonds, plus the amount of
chemical bonds broken via geothermal vents and asteroid/comet crashes
(and perhaps lightening strikes also may be significant, I don't know).

So you need to get better figures that don't compare the total amount
of energy (mostly IR/vis) but *only* the UV from the Sun, against the
other sources of chemical bond-breaking.

> The energy source can do one of 3 things - continually get hotter -
> everything burns up

No, it doesn't work like that. As an object gets hotter, it radiates
more energy, and for any given input of energy there's an equilibrium
temperature where radiation equals input so it doesn't get any hotter.

> continually get colder, everything shuts down

Same logic. If the initial temperature is hotter than equilibrium, it
radiates more than it receives, so it it cools toward equilibrium.

> randomly gets hotter and colder - no chem system can adapt to random
> actions

Only if the energy input randomly varies. I assume that's what you
mean. But this is moot because adaption isn't needed for a simple
replicator.

> cyclical heat cycle - the only thing that fits.

A cyclical heat cycle only causes temperature to vary in a cyclic way,
which might produce a back-and-forth state change (evaporation and
condensation). But it doesn't invoke any chemical changes, any bond
breaking, unless the temperature gets very very hot, like thousands of
degrees, much hotter than you're talking about from Solar radiation,
but much like geothermal vents (deep inside) and asteroid/comet crashes
(immediately adjacent to crashed material) produce. If you want to
claim that heat change is the only source of "interesting" chemistry
during the pre-biotic times, then you've eliminated the Sun completely
as a cause of abiogenesis. But if you include UV-induced bond-breaking,
the the Sun is back in the game.

> Thermal vents have all kinds of problems associated with them.

I'm still waiting for your argument to that claim.
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