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!

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

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.

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.

There are several incompatible definitions of "Singularity" floating around, as pointed out by Eliezer Yudkowsky here: http://www.singinst.org/blog/2007/09/30/three-major-singular...

I personally subscribe to the "Intelligence Explosion" idea, because of two very simple beliefs:

  - AI is feasible.
  - AI will have a profound impact on our lives.

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?

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.

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.

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.

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?

As far as we know, life is not something that happens often nor easily, and there isn't any significant indication that there's life on Mars. So far it seems like we've picked our favorite hypothesis (that there's life on Mars) and are now scurrying around looking for any bits of evidence to support it. "Oooh look, there's some water! And some silica!"

I'll avoid drawing the obvious comparison to creationism. Oops, too late. ;)

When you look at the way evolution works, it becomes clear that there is life elsewhere. Let's take a set of atoms. When they're bombarded with energy they react with each other and form compounds. While predictable, there is a slight amount of randomness in this. Eventually, one of these will be able to replicate itself. A simple example is a structure that would interact with other molecules to help them react to produce a duplicate. This is a biological enzyme. The current hypothesis is that early life was just RNA. RNA is a carrier of genetic information, but also can be an enzyme. Common examples are ribosomes, which read the genetic code and make all our proteins from that code, and self-splicing introns. This early RNA was probably able to produce copies of itself. This is life.

We see certain molecules important for life, such as a sugar molecule, as being meaningful and special. However, as far as nature is concerned it's not. Take a deck of cards. If you were to shuffle them up, they appear disordered, but that's only because we don't give that particular order a meaning. It's just as probable to get that particular order as it is to get them Ace, king, queen, jack, etc.

So basically, life will eventually happen given a long enough period of time. It's inevitable. Life flourished on Earth. Given another very similar system, it's highly probable life was also present there at some point.

Given a sample size of 1 planet (Mars), it seems like wishful thinking, unless you think that life is very likely to develop on any planet that is Mars-like. So if you say "I think 90% of Mars-like planets will develop life", then it makes sense. Hell, even if you only give it a 2% chance, we could poke around some. But I bet even if we assume that Mars and Earth have had similar conditions, it would take many thousands of Earth-like planets (at least) before we find another instance of a life-like system, even optimistically.

The thing is, this fungus would be arguably much more successful than humans.

That would have to be one hell of a protein.

I mean - we sit on a huge pile of matter called the earth.

As for a planet that is Earth-like (or Mars-like when Mars was similar to Earth), I think it is a 98% chance or higher. I'd be willing to bet that if life was wiped out on Earth, it would occur again in a billion years or so. It just seems like matter in general has the tendency to organize and behave in a way that favors life. It does things randomly, but once something happens that can kind of reproduce, it stays around. A bunch of these accumulate until it starts to resemble a cell.

Many chemical reactions in life would happen on their own in enough time. We use enzymes to make this happen faster. Early life takes a long time to evolve up because it doesn't have these enzymes, so it has to wait for the reaction to just happen.

Consciousness, or what we consider consciousness, is perhaps another story.

I suppose this is where we disagree. I put it at well under 1%, even if we were to assume that the panspermia hypothesis is true.

On the other hand, assuming panspermia, there's enough of a chance for life to be on Mars given the fact that its neighbor has life. Finding life on Mars could also lend support to the panspermia hypothesis.

Note: If that seems high it's about the same as 1 chance in 1000 per million years for any form of life to show up.

I now proclaim that all balls in the urn are red.

Anyway, life need not be a complex process: http://www.livescience.com/animals/060609_life_origin.html

It might seem odd for a random process to end up with a life form but there are a lot of possible life forms that could work. AKA picking a single winning lottery ticket is hard but winning the lottery is not that hard if you could buy a million tickets that never expire.

When we are already there and with Mars being the most habitable planet in near vicinity, searching for life there seems like an excellent proposition. Stable atmosphere, not too hot or cold, close etc. What better place to check out? The philosophical implications of finding something would be great. And if not; it would be worth the effort.