Doubting Didymus

DNAunion,

On this I agree with you completely.

Basically, it's a fairly grey area just what constitutes life. Is a rock alive? Replicating clay crystals fit the OOL definition. (they probably were not the ancestors of life, but they certainly replicate). Is a molecule alive? does it 'come alive', just because it can copy itself? It depends on your definitions.

So 'Abiogenesis' can refer to a lot of things, depending on your definition of life.

Edit: this post refers to your second post back.

[ September 24, 2002: Message edited by: Doubting Didymus ]</p>

Doubting Didymus

There are far too many assumptions involved in assigning any probability values to Abiogenesis of any kind.

Possibly, but this only holds if you DO assume that RNA was the very first replicator. What if it had simpler ancestors? This is what camaban is asking: We do not know for sure what the first replicator was, so it is completely impossible to assign probabilities.

Personally, (and this is not the opinion of an expert, by any means), It seems unlikely to me that RNA occured by chance. I feel that there is a need for simpler antecedent forms.

I have also said that I don't think it likely that clay crystals are probable candidates for abiogenesis. But the point remains: what if they are? The probability of a given planet having replicating clay crystals is pretty bollocking high in the grand scheme of things. If it were to be discovered that clay crystals did somehow cause the formation of replicating RNA (or a simpler ancestral form of RNA) then the probability takes a giant leap.

So how can you assign any probabilities to abiogenesis without knowing with a fair degree of confidence what abiogenesis entailed?

Camaban

Perhaps the right conditions exist in many places (some deep sea vents, perhaps) and it is happening, but these new life forms are simply getting wiped out so quickly by the more advanced, better adapted life forms that it's not funny.

Jesus Tap-Dancin' Christ

The right conditions simply do not exist anymore anywhere on earth. Any free amino acids were long absorbed by other microorganisms, leaving almost none left. Anything that was able to piece together the little remaining would be summararily creamed by the competition.

However, it may actually be happening in places that we cannot effectively monitor--the bottom of the ocean. It is possible that new life is being created around certain vents, and we simply do not notice it.

Claudia

When I teach basic probabiliies theory to my students, there are some examples I give them which show:
That events of probability zero happen everyday
(impossible implies probability zero, probability zero does not implies impossible)
That something happens "per chance" or appears 'randomly" does not means anything if you do not describe precisely the whole probability law you are speaking about.

So in this case, the probability cannot be computed as we do not know enough of the process implied to define the probability law, and even if it was computed, that the result is very small does not means that it is impossible.

Now, as we know that life does exists, we can only say that "probability that life appeared when we know that there is life today" is equal to one. Which says nothing about the probability law we are looking for.

To go farther, we need a model on how life did happen.
Goddidit is a model (untestable by science).
Panspermia is another model (difficult to test, may be it will be easier to test in the future)
The diverse processes proposed by various abiogenesis proposals are other models, which can be more or less difficult to test.

But we cannot validate a model by the value it gives for probability, because we can be sure only of a conditionnal probability of 1.

[ September 26, 2002: Message edited by: Claudia ]</p>

Gooch's dad

Yes, Claudia, there are some wonderful 'impossible' events that happen every day.

This subject often comes up in a Yahoo chat room for debate. The room often has 40 or so members. What are the chances that those 40 members will be there, chosen randomly from all 6 billion people on earth? The number is far greater than the number of particles in the universe.

The 'probability of abiogenesis' simply can't be calculated without presenting a process. Even though my background isn't in chemistry, I like to use the example of a catalyzed reaction such as enzyme kinetics.

You can't look at the final reaction products and say what the reaction rate was. In the case of an enzyme catalyzed reaction, the reaction would proceed at such a slow rate without the enzyme present, that the reaction pretty much doesn't happen. It might take years to get a measurable amount of reaction products.

In the presence of the enzyme, the reaction takes place in microseconds for moles worth of reaction products.

So knowing the process is essential for calculating the probability, i.e. rate, of the reaction.

DNAunion

DNAunion: Can you give an example of an event whose probability of occurrence was literally 0, and yet happened?

Xixax

Sure, how about the event of my typing these exact words while purposely mispelling speeling.

And then saying, "yadda babbbmoooo michi tichi ugaboom". All of this while scratching my nose with my shoulder and kicking the floor with my heels.

Probability: 0

[Edit: Noted you said LITERALLY zero. I'm not entirely sure you can say that about anything other than logical impossibilities, like a square circle, etc. ]

Did it happen? Unfortunatey ( and to the amusement of my co-workers ), yes.

[ September 26, 2002: Message edited by: Xixax ]</p>

DNAunion

DNAunion: No it's not. It may be close to 0, but it is not actually 0.

DNAunion: Well, the original person talked about an event with probability of 0; not a probability that "seems close to 0".

I am sticking to what Claudia said.

I want someone to show me an event that had a probability of occurring of 0 - actually 0 - literally 0 - yet happened anyway.

Claudia said she teaches this to her classes, so she should easily be able to provide an example.

[ September 26, 2002: Message edited by: DNAunion ]</p>

DNAunion

DNAunion: No reply from Claudia? I guess she didn't know what she was talking about. That's what I thought.