Re: Opinion Poll: Water and Life?

rev.goetz wrote:
John Wilkins wrote:
rev.goetz wrote:
John Wilkins wrote:
rev.goetz wrote:
John Wilkins wrote:
rev.goetz wrote:
What is the probability of abiogenesis on any given planet or moon that
has water?

Zero, unless it also has complex hydrocarbons, and a range of other chemistry
as well. If it has all these in the right proportions and conditions, the
probability of abiogenesis is exactly one.

Or perhaps you are asking for the range of conditions under which abiogenesis
occurs? In which case we can make a better guess than we once could due to
some solid research on the topic, but not give an exact figure.
Well, I should rephrase my question to this:
What is the probability that any given planet or moon has the right
conditions so that the probability of abiogenesis is exactly 1?

Such probability assignments require a sample size of sufficient size to
generalise. There is no a priori probability when facts are the determinants.
We would nee dto have, say a few hundred sample cases with some frequency
ranging from 0 to 1 of cases of life.
I see no reason why we cannot approximate an a priori probability based
on laboratory experiments. Perhaps we do not yet have enough
experimental information to do this, but it is a possibility.

snip

Suppose we can do experiments to generate life in the lab using a realistic
set of assumptions. To estimate the probabilities, we would need to know how
many *other* kinds of reactions could generate something living, and also how
many *locations* had the prior conditions for any of these. It doesn't resolve
the problem.

Suppose each kind of N types of possible abiogenetic reactions has M places in
the immediate universe where they could occur. Then we can say that the
probability is the sum of all Ns/Ms (roughly). Now, how to fill in those
numbers? Are there 6 ways to generate life? 6,000,000? How many places are
there? 1? 1 million?

The best we can do, short of a local galactic census of *actual* places with
life, is to estimate the likely ways life has evolved in the one case we do
know, and look around for places that are more or less hospitable. But since
it's not just the planetary conditions, but also the local conditions (for
example, one proposed chemistry involves clay structures as partial
compartments - we don't know if there are similar structures on other
planets). There's no way to give a sensible answer here.

We should (are) examine all potential ways to generate life. (Moo who
ha ha ha ha ha ha:) And we should (are) examine other planets and
planetoids in various ways to estimate the potential conditions in
other solar systems. Then we might see if there was and is any natural
determinism for the origin of life in our universe with roughly 10^22
stars or if the origin of life was unlikely in our universe.

Still too little information to feed into your priors. Think of it like this:
you go into a cake shop and find a really nice fudge slice. You knew nothing
about fudge slices before this, and have no way of finding anything out about
their frequency in other shops. Now, to test how many fudge slices there are
int he city, you count the number of houses and shops. What can you conclude
from this? I mean, you have excluded all factories, parks and streetways...

--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: evolvethought.blogspot.com
Who are you going to believe? Me, or your own eyes?

.

Relevant Pages

  • Re: Is the Universe Fine Tuned for Life? 2
    ... rare elements in this Universe. ... extrasolar planets, all the SETI searches--`but we're not finding. ... "At a minimum of 1.9 Earth masses, ... SETI is looking for signs of *intelligent* life. ...
    (talk.origins)
  • Estimates of life in the universe
    ... I ran across some estimates of the prevalence of life in the universe. ... There are 300 billion stars in an average galaxy and 100 billion galaxies in the observable universe so the total number of stars is 10^21. ... 1 in a thousand of the planets in is large enough to hold an atmosphere ...
    (talk.origins)
  • Re: Atheists are the biggest fools on Earth
    ... universe is far beyond the trillions, ... so let's say that the fact that there is life on this planet shows ... that the planet is here by design. ... the fact that there is life on some planets. ...
    (talk.origins)
  • Re: How anthropic is the anthropic principle, exactly?
    ... Isn't it so that our planet is 'earthlike' just because it has life? ... universe is to human life, and even in an anthropic-principal, ID sort ... To evaluate the probability of life as we know it properly you would ...
    (talk.origins)
  • Re: Estimates of life in the universe
    ... There are 300 billion stars in an average galaxy and 100 billion galaxies in the observable universe so the total number of stars is 10^21. ... 1 in a thousand of the planets in is large enough to hold an atmosphere ... and concluded there should be at least 100 million planets capable of supporting life in the universe. ...
    (talk.origins)
Loading