If you did receive my first post please ignore it since I
have made some minor additions in the present.
At 08:51 PM 11/30/98 -0700, Kevin wrote:
>
>
>>Sorry about the delay...
>>
>>At 10:22 PM 11/15/98 -0700, Kevin wrote:
>>>Greetings Brian:
>>>
>>>"And the people that Miller refers to as 'considerable opinion', do you
>>>think they were just making stuff up out of thin air?"
>>>
>>>Of course not, by if you look carefully at what they say instead of
>reading
>>>into their words what you want to believe you will see that they are
>>>referring to the time period between 2 and 4 billion years ago, not the
>>>period between 4 and 4.5 billion years, when Mason says the reducing
>>>atmosphere would occur.
>>
>>No, this is false. Further, you have a bad habit of jumping to
>>conclusions, i.e. your statement that I'm reading in what I
>>want to believe. Will you stop? I'm also curious why
>>you claim that I will find something that is clearly not there.
>>Can you explain?
>>
>
>I have read the papers in question; none of them mention the period prior to
>4 billions years but all talk about the period after. Since you insist that
>they do talk about the period prior to 4 GYA when in fact they do not I had
>to conclude that you were reading into them what you wanted to see. The
>only alternative is that I misunderstood you, but your comments above seem
>to suggest otherwise. Did I misunderstand you?
>
This seems to me to be the key issue and I believe we need to
clear up whatever misunderstanding there may be before continuing.
If what you claim above were true I would be more than happy to
concede.
I don't know what papers you are referring to above but its hard
to believe they are those which Miller refers to since your
conclusion that they do not talk about the period prior to
4 billion years ago directly contradicts what Miller says about
them. Perhaps you are reading the wrong set of papers? Here's
a repeat of the Miller quote:
"There is considerable opinion that strongly reducing conditions
were never present on the primitive earth, but this would mean
that the organic compounds must have been brought in on comets
and meteorites, and this assumption has its own set of problems."
--S.L. Miller, 1992, "The Prebiotic Synthesis of Organic Compounds
as a Step Toward the Origin of Life," in _Major Events in the History
of Life_, J.W. Schopf, ed., pp. 1-28.
My own reading suggests that Miller is exagerating a little in the
above. I cannot find any reference saying that strongly reducing
conditions were *never* present. Instead, most argue that if they
were they would only last a short while, for example:
=====
"A hydrogen-rich primordial atmosphere either never existed or
survived only a short while, many geochemists believe"
-- Richard A. Kerr 1980. "Origin of Life: New Ingredients
Suggested," <Science> 210:42-43.
=====
It is also hard to understand how you can maintain the above
in light of the quotation which I just gave from Kasting.
If you read it again you will see that it also directly
contradicts your claim. Here's a repeat of the last sentence
of that quote:
"The Earth's core probably formed simultaneously with
accretion (10,11); thus, metallic iron could have been removed
from the upper mantle, and volcanic gases could have been
relatively oxidized starting as early as 4.5 billion years
ago (Ga) (12,13)." -- Kasting
If you would like other references I would be happy to provide
them. Or, you could look at the Kasting paper which, being a
review paper, has many of the pertinent references.
This is the main point I wished to establish. If you will
acknowledge this point then I will be happy to conclude this
discussion.
Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University
"He who establishes his arguments
by noise and command shows that
reason is weak" -- Montaigne