Perhaps it is somewhere in between, but thanks to the ginormous distances between stars that it may be likely a very rare occurrence that one intelligent species will ever meet another.

When dealing with numbers that could be as high as a trillion (number of galaxies in this Universe), you might as well say that anything is possible. Predicting the odds of other planets and other life-forms is impossible when the only real evidence you have is our own system. That would make the odds One in Eight. Even if it was one in a billion that still gives us hudreds of billions of planets with life.

If we are that special in this Universe there should probably be a word to describes our special state.

Yeah, the odds of us encountering aliens are depressingly long.

Unless it turns out that it's actually pretty likely for life to evolve, and it keeps turning up in hilarious and unexpected ways on all manner of strange planets.

If the universe can be proven to be infinite, life forms similar to us (or at least similar enough to communicate with on some level), are not just a possibility, they're a certainty.
Unfortunately, given the vast distances of space, we may never find them.

Yeah I think we are still concerned with the whole 'space travel' thing and the light speed limit. Even communications would take hundreds to millions of years to get from once place to another.

That right there is what they call the argument from personal incredulity. Also, which is worse, you misrepresent his point. He doesn't argue that Earth is unique, just that the evolution of intelligence is less likely than the Drake equation suggests. In effect he's just adding another term.

A good and not too technical book on the Fermi paradox was published recently. It's called "Where Is Everybody?" and is worth picking up.

But GOD isn't interested in making life happen on THOSE planets. We're special damnit!

For the record, I agree that the scale simultaneously makes other intelligent life likely, and actually meeting it very unlikely. And it's the time scale as well as distance. Humans have been around for such a tiny, tiny fraction of the universe's age. Odds that another civ developed in that exact same time span? Eh...not so good.

It will be fun exploring their ruins though.

A friend of mine jokes about how we can't find intelligent life out there because it knows about us, and is hiding.
She thinks the Earth is the universal equivalent of a leper colony with a big sign saying, "Actung! Humans!".

The problem with both equations is that they don't address the problem of how we define Intelligence, in that the definition is inherently anthropocentric. We have Millions of diverse species on this planet, only a handful are intelligent in any meaningful way to us humans and none are intelligent in a way that allows for easy communication, and certainly not complex information exchange at a distance.

While there may be billions of intelligent species out there, the odds are they are not even remotely like us. Imagine trying to have a conversation with a dolphin or a chimpanzee. Now imagine trying to talk to a dolphin or chimpanzee that is 3000 light years away and doesn't know how to use a radio.

Well, if the universe is truly infinite, then an infinite number of probabilities is possible and sadly one of those is that we are alone. As I said last week, none other than Arther C. Clarke suggested this, even though he hoped it wasn't the case.

The big flaw is that he presupposes life needs Earth-like conditions. This demonstrates a clear bias to certain kinds of chemistry.

We've demonstrated that properly diddled plasmas can create self-replicating patterns. I don't think the question is: will we encounter non-terrestrial life, but "will we recognize it as such"?

I think there are plasma based "organisms" reproducing in our sun. Possibly even the Earth's magnetosphere. Almost certainly in Jupiter's.

We just haven't told the right joke yet.

Again, the sample size problem.

If there's any sample size issue that needs to be hammered home again and again, it's the "time required for intelligent life to develop" canard.

Earth was populated by simple organisms for a long, long time. Most of the time life existed here, it was very simple life. No one knows why that life didn't evolve faster-- probably because simple life is *effective* life, and Darwinian pressures increase only as the life gets more advanced.

That said, there's no *known* reason why life on another planet couldn't evolve at a far faster (or slower) rate.

Doesn't mean intelligence would develop-- that's a whole other kaboodle-- but advanced life might be far more common than we suspect.

I think it's pretty damned hard to make any conclusion seeing as how we can't really have any good idea as to what the hell's out there. Light from the most distant stars left there billions of years ago, and is only just reaching us. Imagine what the universe must really look like beyond the threshold of intelligence emerging. Future space travelers traveling faster than light will no doubt hit that bubble, and be bombarded with the broadcasting history of whatever civilization we encounter, watching as their techniques evolve as we travel through the layers of the bubble.

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us" ~ Bill Watterson

I heard this guy twice on NPR last week. The simple flaw in his logic is thus: even factoring in the age of a planet, if you look at the rate at which progress is made, even on the scale of billions of years, when a species on a planet achieves consciousness, it expands rapidly and drives technological advancement in its wake. If we take true human history to be only a few million years old compared to 4.5 billion years for the Earths age, then look at how in that span of a few million years mankind was able to evolve to the point it is now, if we extrapolate, it become clear that mankind will at some point outgrow this planet. If we don't destroy it or ourselves first.

So, while the Earth has a finite span in which it is habitable, the fact is our technology is advancing rapidly enough that eventually we can grow beyond the need to be dependent on Earth. It's the "putting your eggs in more than one basket" approach. Once a civilization has advanced to the point that it can easily leave it's own world and colonize others, then it is no longer chained to its original home. That means that a civilization can expand enough to outlive it's original home.

Mind you, even given this, we're still bound by the laws of physics. there may indeed be millions of plaets with intelligent life around, but if they do not find a way to go beyond relativistic space travel, then our chances of encountering them in the average human lifespan are pretty remote.

@Gyrus: There's nothing anthropocentric about math and physics.

There may be all manner of "intelligent" species out there, but once a certain point of intelligence is achieved, technology is technology is technology. That doesn't mean the aliens will look like us, sound like us, let alone think like us, but radio waves are radio waves, lasers are lasers, etc.

The time gap problem is real, however. Even if aliens are "slower" than us by an order of magnitude, a species a million years older than us still would be far more advanced than us, and probably no longer as concerned with discovering other intelligences. Although, again, the disparity might not be as great as the "chimp is to a human" scenario-- while other species on Earth show intelligence to varying degrees, only humans have radio telescopes-- even highly advanced aliens completely removed from mundane concerns can recognize the major differences between the most advanced species on Earth and the NEXT most advanced species on Earth.

Humans *are* special, and unique. And would be so to any intelligent observer capable of noticing. They might not *care* about us, but they wouldn't necessarily regard us as insects, either.

@Gyrus: Why are the odds that way? It's probably more likely that the majority of them are unlike us, but with the huge numbers involved odds are that a slim number of them are like us.

And, frankly, the ones that are like us are the ones we're searching for, because they are the only ones we'd be able to find and deal with.

There is plenty of life besides that on earth. As far as distances, our knowledge of space-time is very limited. I'm sure that during Ben Franklin's time the idea of one person instantly communicating with another on the other side of the world was unthinkable. Today I can just call my aunt on her cell. We just don't have all the right technologies yet to properly explore space.

@Dunny0: Having to shave down the criteria to the ones who are like us makes the number so small, as to be statistically unlikely. Seriously, we're in the 2% margin of error by this point.

And yet, we're somehow going to be looking in the right direction when the Vulcan's million year old radio beam pass is this side of the universe?

We're not only looking for a needle in a haystack, but the haystack is half way across the universe and was fed to cows several million years ago.

I'd like to be wrong, but frankly, it makes more sense to focus on breaking through communication barriers here on Earth, where it can be put to good use.

The drake equation was too... unimaginative in my opinion. He fails to account for the possiblity of non-terrestrial sentience. Until we nail down the exact physical cause of intelligence, we can't even be sure that gas clouds aren't aware.

Perhaps there is a governing body which, for arguments sake, we'll call a "Federation" of planets and they have an all-encompassing directive of non-interference of any form until a certain level of social and technological sophistication is attained. We'll call this hypothetical policy...oh, a "Prime Directive". Maybe we're just not there yet. Anyone thought of that?

@workingonyourinvoice: So true. Our data sets are millions, billions of years out of date. Who knows what's happening out there in real time. All we get is the history channel 24-7.

@Gyrus:
Very true on both counts. At this point, I'm pretty sure the discovery of alien life would tear this world further apart rather than do any good.

It is almost inconceivable to think that among the unfathomable numbers of stars and planets scattered across the universe, it happened only once.

So, you're telling me there's a chance.

workinonyouinvoice - Great idea, that would make a great scifi story.

Until we obtain some actual evidence about extra-terrestrial intelligence - signals, artifacts or direct contact - the best answer to the question of their existence remains "maybe." You can't make a valid prediction with just one data point, which is where we sit now knowing only about ourselves. Attempts to quantify this issue are just plain silly. Accept the uncertainty, people.

We Humans want to think we are special, but we have a powerful inclination to conflate 'special' with 'unique'. I think I'm pretty fantastic for being able to do the things I can do, and it doesn't really matter to me whether or not other people can do them.

Imagine if Columbus landed in the New World, and picked up a single leaf from a tree. Would that be representative of the entire Americas? Could he learn more than the tiniest amount about the continents? Of course not, it's ridiculous, and he'd be a laughing stock. But that sample size of a single leaf would be massively, massively better than the sample size we are talking about here.

I don't know if there is or isn't life, and all I have is probability. I don't know any specifics except that there are a bloody lot of stars and a bloody lot of galaxies. Speculating beyond that is a bit silly I think.

@beercheck: Yes, there is a chance of that, in the same manner that there is a chance of my entire body spontaneously teleporting to the next room. The chance is vanishingly small, so utterly, unbelievably remote that to call it "impossible" is a problem only for the nitpicking mind.

but when do we get to have sex with bluegreen alien babes?

@Ghede: Someone's been watching way too much Star Trek...

Cognitive properties are the result of chemical reactions, specifically, reactions between heavy chemicals not present in amorphous clouds of light gases.

But if you'd like to take a survey of all the helium tanks to see what they think about it, be my guest.

@notworkin: Probably a while, but until then,
[gizmodo.com]
Enjoy.

I find many of these studies to be very limited in scope and imagination. For instance, the whole "habitable zone" thing (both within star systems and within galaxies) - bollocks. Habitable for humans maybe, but life can be found in many, many places that are uninhabitable to humans. They've found mold growing inside Chernobyl's main reactor that eats plutonium for breakfast (literally).

As for intelligent life, I think that's likely too. Intelligence is often selected for in many species, and perhaps given a few hundred million more years dolphins or chimps would become as smart as us. We just go there first, and mainly by accident I think. But we're hardly unique in selecting for intelligence - we just took it the furthest.

That said, unless we can overcome relativistic limitations on space travel, the distances involved impose a serious limitation on our ability to ever meet those other intelligences. And that supposes they didn't die out a billion years ago.

If Tom Cruise says there are aliens out there, then they must exist! 7 million scientologists can't be wrong!!

The problem with things like the Drake equation, is that they're meaningless.

Putting a bunch of numbers into a spreadsheet doesn't make the answer any more accurate than the data originally input. Since all of the data input into the Drake equation are guesses, then the output is also a guess.

Garbage in, garbage out.
-Kle.

I'm no evolutionary biologist, but including time as a factor seems to be unrelated to the issue of any emergence of intelligence. Yes, our planet was around for billions of years before life at all existed, but that doesn't mean all of them must exist for so long. Our models of solar system formation are likely to be seriously challenged as we improve our technologies to detect exoplanets.

Beyond that, once life exists, what is to stop intelligence from appearing quickly? Mutations are random, selection is not. With a large enough sample size, there have to be some planets on which life would approach "intelligence" much more directly and quickly, that's just the odds. There is no time-based reason why humanity did not emerge before the dinosaurs. The conditions to allow it simply weren't appropriate. On one of the countless other planets, that doesn't need to be the case.

Either way, "Bollocks" ought to be used as a tag much more often.

@Ghede: Interestingly, I am always aware of my gas clouds.

For one thing, not every solar system follows the same life pattern as ours.

Like you or anyone else actually knows...

All this blah blah blah proves is the utter uselessness of the Drake Equation. Like Kelbert said, G.I.G.O.

@amorphous:
"Beyond that, once life exists, what is to stop intelligence from appearing quickly?"

Slightly more efficient ants who can grow fur on command.

First off, there's no evidence that intelligence is a natural consequence of evolutionary processes. It could be that the cost of it is such that it may usually be beaten out at an early stage by simpler approaches to the problem of survival. There are an awful lot of examples of very stupid animals that have been around for a lot longer than us, with no or only basic morphological changes. Some of them eat us.

Also, if you think about what advantage it does give you, it's probably the ability to react quickly to changing environments. On a planet with less frequent environmental changes, there may not have been a benefit to it. On a more variable planet, it may not have worked as well as other strategies.

@Brock: As for intelligent life, I think that's likely too. Intelligence is often selected for in many species, and perhaps given a few hundred million more years dolphins or chimps would become as smart as us. We just go there first, and mainly by accident I think. But we're hardly unique in selecting for intelligence - we just took it the furthest.

Dolphins and chimps are as smart as us, they just express it differently. My point was that looking for intelligence Out There that is like us is foolish because most of us can't even recognize intelligence Down Here when it's in a species that is 96% genetically identical or has flippers. if our criteria for recognizing intelligent alien life forms is that they walk up and says "Live Long and Prosper," than we won't ever find intelligent aliens, no matter how fancy the math.

@Gyrus: To say that we'd miss a radio wave if we're not looking in the right direction to detect a it from a distant civilization is not really accurate.

That implies that they shot one burst specifically in our direction and we missed it.

What we'd likely get is the remnants of their early communications, which we can assume would be continuous broadcasts since the invention of radio, radiating out from their planet.

I guess if their planet were like ours, with an uninhabited region that was facing us, we would not see any of their radio waves.

Life may not be all that rare, but intelligent (sentient) life may be another matter. We are the only sentient/technology using lifeform on this planet. But there are millions of different kinds of lifeforms we share it with. The real problem of finding anyone similar to us is one both of time and distance. Our galaxy is immense beyond human reckoning and traverse time between even nearby stars is reckoned in years even at the speed of light. And there are billions of such galaxies in our universe, the closest whose travel time is reckoned in millions of light years. The time factors when a sentient species might make a voyage to even the nearest stars are a tiny wink of an eye in the universal time frame. Missing each other by a few tens of thousands of years, is the time equivalent of nothing compared to the billions of years the universe has been around.

Unless someway is discovered to circumvent the physical limitations on speed while traveling in space, the time frames and distances are just too vast to give much hope of actually interacting with another sentient species (who even if found would probably be either vastly ahead or behind us technologically). You might also think that any sentient species that took the trouble to visit Earth in the last several hundred million years, would leave some sign they had been here to whatever sentient lifeform might evolve.

My personal belief is that aliens do exist, and have spent the last couple of thousand years (at least) trying to prove that there is intelligent life on this planet. I'm pretty sure the advent of reality television has set their research back centuries.

@kstop: My argument is not that intelligence is the end-game, but it is the greatest advantage one species can have (barring whatever the next step beyond mere "intelligence" is). Sure, intelligent species can react faster than others, but the main advantage is that they can plan.

We know where our next meal is coming from. We know how to protect our offspring from disease. We don't have to wait for mutation and selection to do it for us (which is not to say that we are no longer evolving). I don't think environmental variation is a biggie in considering the benefits of planning.

It goes back to my argument of randomness. It's like the infinite monkeys on infinite typewriters: There must be some planets where intelligence would manifest itself relatively quickly.

Of course, like you mentioned, on the flip side there will be many planets where it never comes about, but this in no way means that intelligence isn't a great advantage.