"Can one
assume", Mr. Tappin inquired, "that if lightning occurs in the Archean era atmosphere, one
will observe amino acids being formed as occurred in the Miller experiment?"
"No, one
couldn't assume this", the professor remarked. "In point of fact, the Miller experiment
involved a continuous circulation of the gases through the chamber where the electrical
spark was being discharged.
"Initially,
molecules like formaldehyde and hydrogen cyanide would be synthesized. Then, as these
molecules, along with the original gases, continued to be exposed to the electrical
discharge of the spark chamber, slightly more complex molecules in the form of amino
nitriles would have been formed.
"Amino
nitriles plus water plus continued exposure to the electrical discharge yielded amino
acids such as alanine or glycine plus ammonia. There also were a variety of amino acids
synthesized which do not occur in any of the biological organisms with which we are
familiar. "
"Professor
Yardley, you have previously testified", Mr. Tappin indicated, "that extremely tiny amounts
of hydrogen cyanide were formed when artificial lightning was discharged in a
methane-dominated gas mixture, and, you also have testified that hydrogen cyanide was
generated during an early stage of Miller's original spark-discharge experiment. Is this
correct?"
"Yes, it is",
Dr. Yardley remarked."
"You also
testified that formaldehyde (H2CO) is generated during one of the early stages
of the Miller experiment. Are there any findings concerning the production of formaldehyde
in the artificial lightning studies of which you are aware?"
"In the
limited studies that have been carried out, replied the professor, no formaldehyde
formation has been detected. Furthermore, as far as I know, even the figures which come
from purely theoretical thermochemical calculations indicate no formaldehyde formation is
to be expected in relation to lightning discharges, whether these are artificial or
natural."
"Yet, Dr.
Yardley, in the Miller experiment, the formaldehyde produced by spark discharge combined
with the hydrogen cyanide produced by spark discharge and entered into reaction with
ammonia, one of the gases in the supposedly simulated Archean-atmosphere of the
experiment, and all of this resulted in the formation of amino nitriles. Is this correct,
Professor?"
"That's
right, Dr. Yardley agreed."
"Isn't it
also the case, Professor", the lawyer inquired, "that researchers believe ion-molecular and
free radical reactions, rather than lightning-like shock synthesis, are the essential
processes involved in synthesis reactions in spark discharge experiments?"
"Yes,
acknowledged the professor."
"In what
sense, then, Professor", asked the defense counsel, "can one say the Miller experiment is a
simulation experiment, given that it probably simulates neither the atmospheric
composition of the Archean era nor the character of lightning discharges, nor the products
of lightning discharges, and given that, previously, you have suggested amino acids were
formed in the ocean through a Strecker-like synthesis process rather than in the
atmosphere through electrical discharges?"
"As far as
the features which you have pointed out, replied the professor, the Miller experiment
really isn't much of a simulation experiment. What it does show is this: if one
continuously exposes a gaseous mixture of the right molecular composition to an electrical
discharge of a certain magnitude, one can generate a series of chemical reactions that
will culminate in the formation of complex hydrocarbons which have implications for
origin-of-life issues.
"One would
have had, perhaps, a closer simulation of certain aspects of actual Archean era prebiotic
conditions if one had removed the products of each activation step so that the products of
one set of reactions would not have been exposed to the energy source a second time. This
process of removing synthesized reaction products at each step of the experiment would
have simulated, to a degree, the passage of molecules, synthesized in the Archean era
atmosphere, to the ocean, where they would have been protected from further exposure to
various forms of energy impinging on the atmosphere."
"Dr. Yardley,
wouldn't one have an even better kind of simulation", Mr. Tappin asked, "if one exposed the
products of each reaction step to all of the conditions and forces that could have acted
upon them in an Archean era context, including the ones which could decompose or destroy
such products?"
"Yes, I guess
so, agreed the professor, but there is a practical limit to what can be accomplished in
the laboratory."
"But", the
lawyer countered, "wouldn't you agree that the more we will allow such limitations to
distance us from the actual conditions of the world, then the more we will introduce
potential sources of distortion, bias and error into our experimental procedure? Moreover,
wouldn& #146;t these kinds of distortions skew our capacity to interpret accurately
the significance of what our experiments have to say about the nature of the physical
world, whether in relation to the natural phenomena of our present day, or those of the
Archean world?"
"I would
agree, responded the professor, that we must continuously seek to probe the limitations of
our current experimental methods in order to devise, where possible, better experiments
and procedures which will permit us either to overcome, or compensate for, such
limitations."
"Professor,
one could agree with every word you have just said", Mr. Tappin maintained, "but your words
do not address or answer the problem before us. More specifically, we need to determine
the extent to which these alleged simulations, calculations, estimates, experiments,
conjectures, hypotheses and models of prebiotic, evolutionary theory actually reflect the
conditions, forces, processes and dynamics of the Archean era Earth.
"Yet, on the
basis of testimony which you have given, Dr. Yardley, Miller's experiment does not appear
to simulate, or emulate, the Archean era world in any way. What his experiment seems to
establish is this: if you do certain things, certain things happen.
"Given that
the things which the experiment has done are not necessarily what happened in the Archean
era world, then, the fact certain things have been observed to happen may be interesting,
intriguing or suggestive, but they don't necessarily shed any light on what actually took
place during prebiotic times. Isn't this so, Dr. Yardley?"
"I would
agree", the professor admitted, "that the Miller experiment, or others like it, do not
necessarily prove or demonstrate what may have happened in the Archean era world.
Nonetheless, such experiments generate data that can be incorporated into a process of
theory construction which permits the scientific community, over time, to understand, in a
consistent, rigorous fashion, a wider and wider body of technical information about an
array of interconnected physical and chemical phenomena."
"Yes, Dr.
Yardley", Mr. Tappin said, "but the question is this: to what extent does this condition of
understanding a wider and wider body of technical information about an array of
interconnected physical and chemical phenomena in a consistent, rigorous fashion provide
one with a correct understanding of what actually did happen during the Archean era...
rather than with just an understanding of what might have happened or what could have
happened if all of the conditions, assumptions, and conjectures on which that scientific
model is founded were really true? You see, Dr. Yardley, I'm far from convinced
evolutionary theorists know, or have any way of proving, whether or not their belief
system is capable of getting outside of itself and reflecting anything of the actual
nature of reality."
"Objection
your Honor", announced Mr. Mayfield. "My learned colleague is making speeches."
"Yes,
sustained", Judge Arnsberger indicated. "Let's move along, Mr. Tappin. You'll have time
enough for this sort of thing in your closing remarks."
As the
counsel for the defense looked over the papers in his hands, he said: "Very well, your
Honor. I apologize to the court for my outburst."
Turning
toward the witness, Mr. Tappin asked: "In the Strecker-like, amino acid synthesis scenario
which you outlined during direct examination testimony, on what chemical reactants does
this kind of synthesis depend?"
"As long as
the concentrations of hydrogen cyanide and aldehydes, such as formaldehyde, do not drop
too low, pointed out the professor, then researchers believe the Strecker synthesis will
be an effective means of converting the aforementioned reactants to amino acids over the
course of some 10,000 years."
"What
concentration levels", queried Mr. Tappin, "are considered to be minimally necessary for the
Strecker synthesis process to be able to proceed?"
"These would
be roughly of the order of a 10-6 molar solution, Dr. Yardley replied. This
means there should be at least 10-6 , or one-millionth, of a mole of solute for
each liter of solvent."
"What kind of
collective production rates, asked the lawyer, have been estimated for, say, hydrogen
cyanide as a result of ultraviolet radiation, lightning discharges, and shock-synthesis?"
"The figures
which I have seen used most frequently", Dr. Yardley answered, "have an upper and lower
boundary. These boundaries reflect whether one is talking about a reducing or a relatively
neutral atmosphere.
"In the case
of a reducing atmosphere such as methane and ammonia, researchers have worked out a
production yield of about 100 nanomoles, or 100 billionths of a mole, per square
centimeter, per year. This would have resulted in a 3.3 x 10-4 molar
concentration of hydrogen cyanide in the Archean era ocean over a period of 10 million
years.
On the other
hand, if one were dealing with a relatively neutral atmosphere, the production rate of
hydrogen cyanide would have been as much as several orders of magnitude less than 100
nanomoles - somewhere around 1 nanomole, give or take a few nanomoles - per square
centimeter, per year. Over a ten million year period, this would have resulted in a 10-6
molar concentration of hydrogen cyanide."
"Therefore",
Mr. Tappin observed, "the estimated concentration of hydrogen cyanide arising from a
relatively neutral atmosphere is right at the minimal limit of what is necessary for the
Strecker synthesis to proceed in the Archean era ocean. Is this correct, Dr. Yardley?"
"Yes, that's
right", confirmed the professor.
