I snip this from DailyKos. It isn't political.

QuoteThe Fermi Paradox is a conundrum proposed by pioneer physicist Enrico Fermi that questions the likelihood of Intelligent Extraterrestrial life. The paradox begins with the Drake Equation or some derivative which guesstimates the possible number of intelligent civilizations in the universe, and then extrapolates expansion rates into the universe from a point location within the cosmos of that species or culture.

The paradox is that there should have been enough ET's over the last 10 plus billion years, that even if they moved at velocities achievable by human technology today, they could have swarmed over the galaxy, or even the cluster to which our galaxy belongs to, many times over.

Clearly, we don't know enough about the universe to draw any firm conclusions from the paradox. Still, it's an interesting thought experiment: Our galaxy is about 100,000 light years from rim to rim and contains perhaps 400 billion stars, each of which could easily have, on average, a half-dozen planets. The galaxy is perhaps 10 billion years old. If there were a single fledgling interstellar civilization in all that space and time, and it expanded away from its planet or point of origin on average at the measly rate of one light year every ten-thousand years, slower than our own Voyager Spacecraft are traveling, and grew in all directions, it would take 'only' one-billion years to get from one end of the galaxy to another and completely fill it up along the way. A little faster, at a mere one percent of the speed of light, it would take only ten-million years to spread from one end of the galaxy to another, and less than a billion to engulf entire clusters of galaxies.

Humans could begin constructing spacecraft that move at these speeds right now, if we put our minds to it. So if we could start spreading all over the galaxy using our current technology, why hasn't someone or something already spread all over us? Once cultures started spreading like this it seems likely a ruthless sort of selection would kick in and favor the culture, or the faction within a culture, which does so the most aggressively, quickly, and successfully. It's hard to see what would stop it. So where are they? Is there anybody out there?

So: your thoughts about all this? How likely is intelligent life, given these assumptions? Why haven't we found evidence for it yet?

The article specifically says humanity could do this but doesn't.  That can apply to other groups as well.

If I remember correctly, the more industrial nations on earth tend towards a low birth rate.  America, for example, depends on emmigration to grow.  Maybe societies past a certain point of development have a low enough aggregate birth rate that they don't expand at anywhere near the speed less advanced ones do.  Why spread out if you don't need to?  

Who says we noticed the alien voyager probe that came by 250 years ago?

Who says they had any interest in earth when they saw it.  A truely alien species is going to be just that, alien, we realy can't guess there motivations or reason for doint things.

What if we are the "elder" race from so many sci-fi stories?  There is always one group that is first, that comes before.  If we are that group, then we have to do everything the hard way and achieve it all.  We can't find another races tech to reverse engineer and use.

What if no one else wants the headache of trying to maintain a society across all that space?  

Planets we find habitable might be scattered enough that we can only use one planet in a 1000 systems.  Without good FTL at that point it might be prohibitively expensive to expand at the rates they are professing.

I love the idea of alien species existing for us to encounter, I hope we find some.

Quote from: Xavier LangI love the idea of alien species existing for us to encounter, I hope we find some.

Considering what usually happened here on Earth whenever natives were discovered by more advanced people... well let's just say I'm not expecting Close Encounters of the Third Kind with aliens coming down to play Simon.

Who says it isn't happening? After all, we have UFO and alien sightings all the time.

I'd say the guesstimates for the chance of intelligent life or, rather, intelligent life that spread from beyond its home planet, are overly generous.  I have no doubt that there is life elsewhere at the moment. The sheer vastness of the universe makes it almost certain. But intelligent life? That has spread out into the galaxy? At this moment in time? Each question makes the odds a bit more iffy.

Quote from: Xavier LangWho says they had any interest in earth when they saw it.  A truely alien species is going to be just that, alien, we realy can't guess there motivations or reason for doint things.

Or if they even recognized us as intelligent. Or if we weren't when they buzzed us.

Maybe we're located in what's considered a protected nature preserve area of the galaxy...

Quote from: ColonelHardissonI'd say the guesstimates for the chance of intelligent life or, rather, intelligent life that spread from beyond its home planet, are overly generous.  I have no doubt that there is life elsewhere at the moment. The sheer vastness of the universe makes it almost certain. But intelligent life? That has spread out into the galaxy? At this moment in time? Each question makes the odds a bit more iffy.

They usually do some sort of equation. They say, what if one out of every thousand stars had at a planet? And what if one out of every thousand of those planets was terrestial, and had liquid water? Wand what if one out of every thousand of those had life? And what if one out of every thousand of those developed intelligent life? And what if one out of every thousand of those had intelligent life that was curious about exploring the universe?

You still end up with an impressive number of intelligent races curious about exploring the universe, just in our galaxy alone.

Quote from: willpaxI snip this from DailyKos. It isn't political.



So: your thoughts about all this? How likely is intelligent life, given these assumptions? Why haven't we found evidence for it yet?

I think that the basic assumptions of the question are incorrect. it's stated that each of the 400 billion stars in our galaxy could easilly have 6 planets. this statement is incorrect knowing what we do about star life cycles and planetary formation.

Consider: it took life on earth millions of years to evolve. In the case of supergiant stars, which meaure their lifespans in the thousands of years, there's no where near enough time. considering the frequency of the larger stars earlier in the life of the universe, that's a lot of those potential stars knocked out of the running.

Fermi's Paradox is based on extrordinarily incomplete data, and in the long run fails to hold up as anything more than an interesting speculation.

Maybe the aliens have some sort of 'prime directive'

Quote from: Name LipsThey usually do some sort of equation. They say, what if one out of every thousand stars had at a planet? And what if one out of every thousand of those planets was terrestial, and had liquid water? Wand what if one out of every thousand of those had life? And what if one out of every thousand of those developed intelligent life? And what if one out of every thousand of those had intelligent life that was curious about exploring the universe?

You still end up with an impressive number of intelligent races curious about exploring the universe, just in our galaxy alone.

I'm familiar with the Drake equation. I think the estimates they use to fill in the blanks in it are too high. I think that because, as the Fermi paradox asserts, if those estimates were accurate, we'd have definitive proof of extraterrestrial, intelligent life.

Quote from: BillyBeanbagMaybe the aliens have some sort of 'prime directive'

What a stupid idea, what kind of backward race would even think of such a concept?

In my day, when the model didn't fit the data, we didn't call it a paradox, we called it a bad model.

There's just way too much guesswork.  When it comes to life bearing planets and technological species, we're dealing with a sample size of one - there's no way to really gauge the variability or probability.

For all we know, a race colonized most of the galaxy and died long ago.  And how would we tell if aliens briefly set up a station here a hundred million years ago.

The Drake equation is a bunch of crap.  It's (almost) completely content-free.  (The approximate number of stars in the galaxy is the only number that isn't crap.)

The number of stars that have planetary systems: we have no fucking clue.

The number of planets capable of sustaining life: ditto.  Theoretically, there could be life in Jupiter's atmosphere.  We don't fucking know.

And that's just the first two variables.  From there, the numbers get even more retarded.  We can make some educated guesses on the above two variables, but we have NO DATA AT ALL to make any sort of educated guesses on the variables from there.

Any attempt at solving this "equation" is simply an exercise in mental masturbation.

Quote from: CyberzombieAny attempt at solving this "equation" is simply an exercise in mental masturbation.

There's nothing wrong with masturbation.