

Mars rover finds signs of microbial life habitat - ingenium
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/12/11/wmars111.xml

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shogunmike
One of the most interesting articles I've ever read on this subject is this:
<http://en.wikipedia.org/wiki/Fermi_Paradox>

Just in case you haven't heard of it, FTA: "The Fermi paradox is the apparent
contradiction between high estimates of the probability of the existence of
extraterrestrial civilizations and the lack of evidence for, or contact with,
such civilizations."

If you get the chance, check it out. Some of the ideas in there are
incredible!

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jey
I don't understand all the hubbub around looking for life on Mars. Is there
any credible reason whatsoever to assign a non-negligible probability to there
having been life on mars? It seems to me like it's a PR trick cooked up by
NASA to keep the public interested. Nobody cares about soil composition, but
everyone is excited by a mission to find Martian bacteria.

~~~
ingenium
Mars almost certainly doesn't have life anymore, except maybe underground or
in caves or something. The thing is that Mars used to be very similar to
Earth, and it's even been suggested that life was seeded on Earth from Mars.
What they are looking for is signs that Mars had life at some point in the
past, because it would prove that life is not something that is unique and
special to Earth.

Also, I would be very curious how Martian life differed from life on Earth on
a molecular level. I'd be willing to bet they were based on the same
principles, but diverged pretty quickly. For example, they may not use the
structure of the amino acid to produce protein, which is:

    
    
          H
      NH3-C-COOH
          |
     functional group
    

If they did, they probably don't use the same codon code to present them in
RNA or have the same functional groups that all Earth based life does.

I'm certain there is life places other than Earth, but the question is what
does that life look like? It may not even remotely resemble Earth based life.
Finding life on Mars might give us a clue about what types of things to look
for to identify life elsewhere.

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asdflkj
>I'm certain there is life places other than Earth,

Any evidence for that?

Edit: this is my pet peeve, and I'm still peeved, so I'll write some more.
Nobody has any idea how probable the appearance of life is. Nobody even has an
idea how it happened. The only thing we do know about that probability is that
it's very low, since we haven't been able to observe life anywhere. Just how
low is anyone's guess. It could be 1/(number of particles in the universe *
googolplex). Or it could be much lower still.

My other pet peeve is singularity. If you show an 19th century man our world
and give him the definition of singularity, he'll tell you it already
happened. That's because it's totally meaningless, and essentially amounts to
this: "singularity is when technological progress goes so fast, that, like,
dude, totally".

There, now I feel better.

~~~
DanielBMarkham
Just playing devil's advocate here, we're alive, aren't we? So the odds can't
be much less than 1/(number of planets in the universe)

As for the singularity, I believe the point is the nature of being a human
will change. The 19th century man will fit into our world just fine. A
"regular" man might not fit into a world where we're all part cyborgs. You are
correct in that it's the same unknowable impenetrable future state for us and
the 19th century guy, but the idea is that the nature of change will be
different in the next 100 years than it ever has been -- because it deals with
what it means to be human.

The Fermi Paradox, Drake Equation, and the quest for life is one of my pet
subjects. I like it because it is pseudo-science -- and I mean that in a good
way. We simply have no means of actually performing experiments, since our
knowledge of life consists of just one example for a brief period of time. I
am tempted to think that life is just about everywhere in the universe, but
heck if I know. If there is life everywhere, then where is everybody?

~~~
asdflkj
>we're alive, aren't we? So the odds can't be much less than 1/(number of
planets in the universe)

That argument takes for granted that the probability space comprises only the
things in our observable universe. In other words, it claims that there
doesn't exist anything that we don't already know about. That's a false
premise.

re: singularity. I think we are already part-cyborgs. For all practical
purposes, Internet is a part of me--it's a sense organ. Ask yourself, what
would you rather lose: your sense of hearing, or the technologies of the last
100 years? For me, it's the former, any day of the week. What it means to be
human changes continuously, and has been changing since before we were
officially human. Now it's changing faster than ever before, but it changed
faster than ever before at almost every point in human history.

~~~
DanielBMarkham
"In other words, it claims that there doesn't exist anything that we don't
already know about." -- that's not a false premise, that's the basis for
science. I can only deal with things I can observe. If you put 4 black balls
and one white ball into a bag and ask me the chances of drawing a white ball,
it's 1/5. If you then say, "hey -- but I really put 9 black balls in there.
Your math is wrong" that's not much in the way of an argument. We measure and
calculate those things we can observe.

Yes, one could speculate on non-observable things. But that's a game that has
no end.

We are conceptually part cyborgs. I think there will be a line that is
crossed, perhaps in our lifetime, where the average person will be physically
part cyborg. No matter how you measure it, that's a change of a different
nature than simple discovery and invention. I think you are muddling the point
a bit.

One of the reasons the Fermi Paradox and Drake Equation are so interesting to
me is that they rely on speculation. While I think the minimum is 1/(number of
planets), who knows what that number is? And for all the other terms in the
Drake Equation, you're just pulling numbers out of the air. It's as much a
religion as science. Fascinating stuff, both from a science angle and as an
observation of human nature.

~~~
asdflkj
"Words break if you push them too far" -PG

I think we are at that point now--at least I am, when I try to reason using
the terms of our previous discussion. (I just realized that this is an
excellent copout when you lose an argument about abstract things! Still, I
don't think that's the case here). Let's approach this from a different
direction.

Is it within the scope of the theory of probability, and its accepted models
in physics, to deal with cases where the observer is determining the
probability of existence of a property that only he possesses? I think the
answer is "no", though I'd really like to know the view of someone more
knowledgeable than me.

But this means I was wrong in my original post, when I claimed that the
probability was possibly very small. It made no sense to talk of probability
at all.

I wish I had the mathematical chops to formalize all of this. Oh well, I'm
still young.

P.S.: re: singularity. I think what I'm doing is exposing the muddle that is
already there. To me, being a cyborg physically doesn't seem very remarkable.
(By the way, doesn't the word "cyborg" already mean "part-robot"? "Part" in
"part-cyborg" is redundant). It wouldn't even be the biggest change to ever
occur in humanity. Perhaps forfeiture of individuality would fit the bill, but
I don't think even the most ardent singularity nuts are very excited about
that.

~~~
Retric
You are making assumptions about the number of life forms in the universe.
Let's say there are 100 billion stars per galaxy and a 100 billion galaxy that
will last for 100 billion years. At this point we think life could be on 1 to
3 locations in our solar system. But we know nothing about the total numbers.
I expect there is some form of life around 3 - 5 million stars in the milky
way and life at 10 ^ 15 stars in the universe. I could be a lot higher or
lower than that but life is a fairly simple chemical reaction so it seems odd
to think it's going to be rare.

Now who knows how many civilizations are out there but there is no reason to
expect to see signs of life in the next galaxy or on the other side of ours.
The best way to think of this is how far away do you think we could detect
life on earth?

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mberning
Need to add the word "habitat" on the end of the title and it would be 100%
correct.

~~~
ingenium
fixed

~~~
mberning
cool

