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Old August 27 2013, 03:26 PM   #36
Fleet Captain
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Location: At star's end.
Re: Whee are the aliens?

Lindley wrote: View Post
Edit_XYZ wrote: View Post
This means that, in order to win the 'lottery' of life, you need more than the atoms in the observable universe. A LOT more.
At any one time, yes. When you have millions of years to work with that acts as a multiplier on "lottery tickets" as well---a fairly large one.

Our ability to design a self-replicating molecule is irrelevant; there are lots of things nature does better than our designs.

I'm also going to question your conclusion that evolutionary forces are irrelevant. Certainly, it wouldn't work in the traditional sense. However, it's possible that certain molecules had advantages (or disadvantages!) of some sort given a particular environment, and this could prune the decision tree considerably.

I'm not saying it's not unlikely, mind.
Lindley, if a molecule can't self-reproduce, it cannot 'spread' its 'advantages'. Other molecules disappearing from the environment also doesn't help it, if it can't self-reproduce. AKA NO Darwinian evolution.
Feel free to post a scenario for Darwinian selection where the actors are not self-replicating - if you have one.

Our inability to design a self-replicating molecule is highly relevant, showing us we're talking about a highly complex construct - that is not easily achievable by putting some environments one after the other. You need some very, very specific environments - so subtle, we didn't figure out which despite a lot of searching (not blindly, but guided by science).

And we're talking about, VERY generously, 100 orders of magnitude between the chances of life existing and the number of atoms in the observable universe that can give birth to life (between ~10ˆ157 and a small fraction of 10ˆ80).
Good luck winning this lottery.

As said, Lindley, you can have all the 6-7 billion years of abyss of time. It barely makes a dent in the improbability.
And you can have the universal abyss of space, considering Earth-like planets as a dime a dozen and taking my 100! only as a very rough/high estimate. The probability of life appearing twice in the observable universe remains practically 0.

CorporalCaptain wrote: View Post
Edit_XYZ wrote: View Post
1. Abiogenesis.
What is the road from a bunch of chemicals to the "simplest" molecules that can replicate themselves halfway reliably?
Let's - VERY optimistically - assume that a specific chain of 100 chemical reactions are enough to create this "simplest" molecule.

Now - Darwinian selection has no part in creating this molecule; for Darwinian selection, you need self-replication, which you do not yet have.
Which leaves probability in charge. For a very rough approximation, calculate factorial 100. It gives a number so close to 0 [sic] as the chance of this "simplest" molecule emerging, that the chances are life on Earth is alone in the observable universe (and a huge chunk of the unobservable one).
Care to explain just what 100! is a "very rough approximation" of in this context and how you know it even is an approximation?
I take it as a very rough approximation because it leaves out many factors:
-In the primordial earth, there were many environments, not just 100;
-As such, the problem of abiogenesis is more correctly stated as: 'these 100 steps should follow one after another without one or more destructive environments appearing between them, destroying the future self-replicating molecule';
-The number of steps necessary to create a molecule that can replicate half-way reliably is probably larger than 100;

In essence, 100! is a simplification, only there to give a rough idea about the improbability of self-replicating molecules emerging.
"Let truth and falsehood grapple ... Truth is strong" - John Milton

Last edited by Edit_XYZ; August 27 2013 at 03:48 PM.
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