Re: A Hypothetical

"On Thu, 18 Dec 2008 10:11:27 -0500, in article
<dcydnTzgzt6G9dfUnZ2dnUVZ_orinZ2d@xxxxxxxxxxxxx>, Jack Crenshaw stated..."

John S. Wilkins wrote:
Jack Crenshaw <jcrens@xxxxxxxxxxxxx> wrote:

With one scientific mission seeking to find life on Mars, another to
find it in meteorites in Antarctica, astronomical efforts to find
life-friendly planets in the cosmos, and the SETI project still looking
for intelligent life WAY out there, the thought occurs:

Suppose that one of these efforts does indeed turn up irrefutable
evidence for life, however primitive. Now suppose we somehow manage to
get a physical sample of said life.

There are two possibilities, both intriguing. Perhaps the life is found
to be of a different kind, reproducing using different methods, or
with the "blueprints" not encoded in our familiar Watson & Crick, double
helix, ACGT way.

I wonder how the different factions would respond to this development.
What would we conclude? I suppose followers of the conventional
"Saganist" view would see this as proof that (a) life is probably
ubiquitous in the Cosmos and (b) there are many paths to it.

Not sure what believers would say, except perhaps that the term "In
God's own image" would have to be much less literal and much broader
than they thought.

The other alternative is even more intriguing. What if we find evidence
of life, and it turns out to use the same ol' ACGT, DNA mechanism with
all the same supporting molecules that we see here.

What do we say _THEN_?

For this case, we'd have to ignore results from Mars. We know that
material has been exchanged between Earth and Mars, so the prospect of
cross-contamination would leave the result inconclusive. But what if
it's from someplace way far away, like Alpha Centauri or further?

Of all the many opinions we often find on this NG, I wonder which one(s)
such a result would strengthen? Never mind the folks who are so
hard-core as to see _ANY_ result as proving their own POV. I'm wondering
what thinking, rational people, if any are left here, would conclude.

I'd be genuinely interested in your thoughts. Please, rational thoughts
only, no screaming.

Jack

The principle of inference I would use is that the more exactly some
instance of life matches ours in detail, given that we know there are a
multitude of possible other chemical systems, the more likely it is that
there is cross contamination, either recently or over time. I would
doubt that we would find straight standard code use of DNA, but I'd not
be suprised that DNA got used in some cases. So standard code is
evidence of common ancestry, while the use of DNA itself is not (because
it's a very stable molecule, although there are others in carbon-based
biochemistry)

Yeah, that's pretty much what I think I would conclude, too. When I
suggested ignoring results from anywhere closer than Alpha Centauri, I
knew that even this was probably not far enough. Since the Oort cloud
reaches about halfway there, we could be getting cross-contamination,
even from there.

All this brings up another interesting question, though. Suppose that
some time in the _FAR_ distant future, we realize the SciFi dream of
warp drive, and can actually GO to other worlds and examine the life
there, up close and personal. Suppose we find the same DNA mechanism
everywhere.

I would not be surprised if there were some scientific method
discovered which would not require going to the world and
examining the DNA to answer your question.


I can see it now. The religious would say, "This proves that God created
all life in His image." The other guys would say, "This only proves the
existence of a common ancestor." In the end, we would have made exactly
zero progress in resolving the question.

Sigh.

Jack


I'm more optimistic than you. Assuming, that is, that there will
be scientific/technological advances into the future (there is
the possibility that a hundred years from now there will be *less*
science than now). The state of the question may not critically
depend on the scenario that you are drawing. Your proposal is
only one way of answering the question, and it may turn out to
be unnecessary to use such a direct approach.


--
---Tom S.
"As scarce as truth is, the supply has always been in excess of the demand."
attributed to Josh Billings

.

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