QUOTE(deadlock @ Apr 12 2007, 07:52 PM)
chance>
re.a Of course there are isolated environments! islands, caves, mountains, deep underwater trenches, thermal gradients, etc. The earth is not one homogeneous place. All that is needed is a little stability of one of the environments, an undersea volcanic vent would easily fulfil that requirement. Plus the environment is sterile (pre abiogenesis) there is no competition, if some stable chemical is formed, it’s there for good, until evolution comes along and [Clint Eastwood] “makes it’s day” [/Clint Eastwood].
Deadlock>
For Abiogenesis isolated environment must be without oxygen, without any uncontrolled source of energy and without water.In the presence of oxygen no aminoacid can be formed.Any source of energy as lightining, heat or UV destroys aminoacids faster than builds them.In the presence of water no polymerization can be done.All this proved in labs.That´s the reason why to build up pepitides is a very difficult and delicated process.
And you suppose such an environment could not possible exist?, even today we find anaerobic bacteria, which if exposed to oxygen will kill them! You don’t seem to be making a point. I have explained that isolated environments can exists, you then go on about what can and cant be stable? The point is that the things well see necessary for life today may have taken a very contorted ‘evolutionary’ path, and something that seems impossible in today’s environment is not applicable to the past. Your making too many assumptions about the nature of the earth and the chemistry that was active at that time period.
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chance>
Re.b yep and to get to that point you must use laboratory experiments to find the conditions that make it work by systematic elimination. I suppose that if you want your specific condition met, you would need to work out in the lab a viable abiogenesis recipe, then take it outside and pour it on a section of sterile ground, stand back, wait, and there’s your proof. Your expecting such a proof (the goal as you put it) to be satisfied by the preliminary steps of figuring out the abiogenesis process, and that is just unrealistic.
Deadlock>
Unrealistic is to make a flawed experiment using conditions that do not exist in nature and say "Oba, Abiogenesis is possible !".
I dispute the point about the experiments being unrealistic, as it’s necessary in these preliminary days to isolate “the good from the bad”. If you poured everything into a pot and lit a flame under it, you would learn nothing.
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chance>
If the same conditions exist, that would be possible, if not then no. That is the major problem, i.e. it being difficult to know what the conditions of an early earth were with any certainty. If the conditions were known we could whip up a batch “instant life” tomorrow couldn’t we?
No, absolutely not, all you need is a localised environment, producing the right conditions. You don’t need a global condition.
Deadlock>
First, Please show me any hipothetical localised environment producing the right conditions.Second, a localised environment cannot have the concentration of aminoacids needed to have the number of reactions per second to face the low probability of the event.As I said to form one molecule of Ghadiri Group the probability is 20^-32.
What are the right conditions, do you know what they are?
I’m certain now one knows for sure because if they did they would start experimenting from that point wouldn’t they! The current experiments are starting from as a basic position as would seem possible, what can be known for sure is more frequent vulcanism, meteoric/comet bombardment, water, and little to no oxygen, after that who knows.
Your probability ‘calculations’ are less than worthless, because you are not in position to know the environmental baseline nor the sequence of the ‘evolutionary’ steps that abiogenesis took.
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chance>
Just as an hypothetical, lets just pretend that the abiogenesis event really does require just 6 stable molecules (SM1-6). Once these molecules meet they will naturally join up and begin replicating imperfectly (and the rest is history). Lest assume that:
SM1 is formed in a reducing volcanic environment.
SM2 is formed by UV light on the atmosphere
SM3 is formed in comets and meteorites
SM4, 5, 6, well you get the picture.
What is needed in this scenario is for the 6 chemicals to meet in the vicinity of an undersea volcano. Given the nature of the formation of the earth, volcanic action, meteorite/comet bombardment, strong UV light were rather more common than they are today, the probability would seem certain that such and event would come about in a watery world.
Deadlock>
a. What kind of miracle is this ? 6 molecules meeting in the vicinity of an undersea volcano?
b. Even if this was possible, I would like to ask if these 6 molecules are aminoacids or some type of pepitides ?
(my paragraphing)
Re.a oh dear me! The idea of an explanation via hypothetical/pretence, seems to have evaded you. The example I gave was to show how likely a single abiogenesis event could be (almost certainly just one of many), no more.
Re.b unknown and unimportant for the purpose of explaining chance meetings of an unknown mechanism.
The whole point is that abiogenesis could have required a thousand similar events (or maybe a single one), some more probable than others. This is why it will be so difficult to determine how abiogenesis began, there are so many variables. It is also why there is no theory.
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chance>
No one is saying this will be easy to get to the goal of replicating abiogenesis. And I dispute the inference that they are going in circles, much has been learned to date. But what do you say to the question that, [i]in principle, producing building blocks of life (amongst other) from non life, is positive evidence for abiogenesis
Deadlock>
You´re again using a requirement as evidence.Producing building blocks of life from non life is a requirement so much for creation as for abiogenesis.
No I am not!
Requirements: The requirements for life are determined by what we find today, DNA, amino acids proteins etc. There is also an assumption that the earth is sterile. There is also an assumption that to get to cellular life, you have to pass through evolving steps.
Evidence for abiogenesis: The evidence is that some of these requirements for life can be created from scratch via rather simple and some would say probable conditions in a pre biotic world.