h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

"If they existed, they would be here." - Enrico Fermi (1901 - 1954)

This is the Fermi paradox concerning the existence of extraterrestrials.
They're not here, so therefore they do not exist.

The idea is that the Galaxies in the Universe are old enough for life to have developed over and over again. There has been more than enough time for intelligent life to colonise our galaxy from one side to the other. Let alone travel the length of it.

So why aren't they here? Because they don't exist.

What are your opinions and/or theories on this?

The good doctor is committing the error of making some assumptions:

1) That such interstellar space travel is possible.
2) That colonization of other planets is desirable.
3) That the rate of evolution is constant on all planets.

We've all seen the movies that suggest that other life forms would have evolved intelligence quicker than we have. What if we're the exceptionally quick? If an extinction level event (yes, I've been watching "Deep Impact" again) had not occurred when it did, perhaps today mammals would still be struggling to produce intelligent life, prevented from true ascendancy by competition with the dinosaurs.

We might yet find our roles reversed... we'll be the ones in the flying saucers, wreaking havoc on the underdeveloped and unprepared civilizations of the galaxies.

My first reaction is to ask, "why is it necessary that they be here if they existed?" My second reaction is to ask, "what proves that they are not, in fact, here?" (That second question might have got me kicked out of ARS were it not for the fact that skepticism does not imply disproof of anything ).

- JD

The idea is that successful species spread out over time, they consume all of the natural resources then move to a new place and do the same there. It follows that they would expand out further than their own biosphere to new planets to find new resources and, perhaps, places to live. The timescale of our galaxy alone is well in excess of the time it would take a space-fairing lifeform to spread itself across it.

That is why they would need to be here, according to the Fermi paradox.

No-one can disprove that 'they' are not here at the moment, of course. But I don't subscribe to the theory. If they were working their way in towards our sun, consuming all the outer planets had to offer them as they went, I think we are capabale of detecting it. And if they have just popped in to say hello, I think they would actually say 'hello', and not just hang around in the shadows playing with the American government.

"Ooh, stay away from earth. It's got humans. They're contagious you know..."
"So, what you're saying Lister, is that you're a giant, pus filled intergalactic coldsore...?"

Or something along those lines. But I think it sums it up nicely.

Blatherskite the Mugwump,

You make some good points, I think they would be the arguements I would follow if I was to think about it enough.

Another possiblity is that there is some galaxy-wide extinction event happening every billion billion (or any other figure) years that kills off any advancing ETs.

"The idea is that successful species spread out over time, they consume all of the natural resources then move to a new place and do the same there." - Amount of time required to produce a successful species capable of consuming all the natural resources of a planet, and likewise capable of moving on: Unknown

Intelligent life-forms could have brought about their own destruction before they achieved space travel, or suffered an extinction level event just as they were getting close. Intelligent life-forms could be prevented from achieving space travel due to anything from lack of resources (there doesn't necessarily have to be uranium or fossil fuels on every planet), to stiff competition with other life-forms (anything from monsters to viruses), to cultural taboos.

And it could be influenced by other strictly cultural influences. Scientific achievement on this planet was slow and plodding until we got religion out of our government. Other civilizations could still be too religious to develop.

We saw our greatest leaps towards space travel as a direct result of international competition... specifically, the threat of war. Other worlds might find themselves unified under a single government, which means no pressure to develop space technology.

There are too many variables. Fermi was *way* overextending himself when he said a space colonizing race should have reached the entire galaxy by now.

To address your last comment first, I also do not subscribe to the multitude of "theories" that alien life forms have been or are already here. I concede the possibility, of course, but that's like saying I breathe air. BTW, I'm ing at the playing with the gov't part ... ahh, would that The Simpson's Kang and Kodos were real ... it sure would explain a lot.

Flake99 said: "The timescale of our galaxy alone is well in excess of the time it would take a space-fairing life form to spread itself across it."

Far be it from me to debate Fermi, but even if that were accurate with today's knowledge (remember, he died nearly 50 years ago) that statement only supports the claim that there is no such life form in our galaxy - there are quite a staggering number of galaxies out there.

Personally, I find the idea a bit flawed; that is, the idea that there should exist life forms much further evolved than us or none should exist at all. We are only beginning to understand the complexity of our own environment, let alone the subtler effects the entire solar system and nearby galactic regions have had on our planet's development (not to mention our own). Until we begin large-scale interplanetary colonization of our own, I maintain we have no idea of the time it takes to reach that stage, or more importantly of what sort of species is required to achieve and continue to support such expansion. I don't buy into the concept that we can say with anything remotely approaching accuracy that we have any idea what the time is that it would take a space-faring life form to develop in the first place, let alone spread itself across the galaxy.


- JD

Heh, Blatherskite and I are competing for the "say the same thing, nearly at the same time, but differently" award.


- JD

I've gone cross eyed. Give me a minute.

JD: But I won by 7 minutes.

Acceptance speech, coming soon...

I'll draft my version right after you.

- JD

Ahem, cough,cough I am here and have been for quite a while.

I would add my bit in agreeance, but I seem to have stumbled on this a bit late and it's all been said already...

Still... famous Dr's should refrain from making sweeping statements concerning things we know little about eh?

Perhaps I can get some govt grant to make statements on deep sea fishing... well, I watched 'The Perfect Storm' once

Wow, loads of points to consider. I didn't think anyone would reply to this conversation.

First, I seem to have fallen into the position of defending the paradox, I don't really believe it myself, but I'll take the other side for the sake of the arguement. If I wasn't I'd be making the same points as you two.

Blatherskite,

I completely agree with all of your arguements, they are pretty-much sound. However, I take it that we are assuming that life is common in the Universe. So, all of your reasons could apply to thousands, if not billions of intelligent species across the Galaxy/Universe. But the Fermi paradox only needs one species to expand... one, out of thousands. Millions maybe. It isn't hard to imagine a few ways to expand across a galaxy, we are capable of imagining such big engineering feats.

it only takes one, sure... but that would mean it only takes one of any number of potential catastrophes to end their adventurisitc jaunt... one misplaced meteor, one supernova, one mis-reading of the navigational charts by an over worked menial...

There are enough dangers in big bad space to make any higher intelligence's colonisation problematic...

Well, you have to consider HOW a potential colonies would spread.
A common theory is that self-replicating robots could be deployed. They would have very basic commands written into them, i.e. 'find certain materials, land, build a factory, build more of yourself, start terraforming the planet etc' So from a single point of origin a swarm of robots could spread in all directions consuming what they need and preparing what they find for their builders to inhabit centuries later. Its not that far beyond our engineering capabilities to build such robots, and we are very, very young. What could a race with a head-start do?

but given the time it would take, is it not inconceivable that sya, during the first 20,000 years (Earth years I suppose) say five of the expeditions are eliminated in a variety of exciting and spectacular ways... and over the next, say 13,453 years another ten could meet similarly interesting ends... or maybe a few dull ones to boot... If we are only talking about one species, there is enough time for them to colonize given the life of the universe so far... however, there is also plenty of time, and potential hazards, to bring a grizzly end to each attempt...

given the comparitive short life of earth, we've had an end to the dinosaurs... and as for humanity, how many empires have come and gone... all lasting seconds in comparison to the universe, and with only an Earth bound, limited number of potential and actual endings...

But if these robots are flooding the galaxy in an ever-expanding sphere, one of the only things that could stop them is a galaxy-wide extinction event. And then everyone is back to zero. Unless there is some friendly race stopping all attempts of colonisation. If so, we are in debt.

and if it is just one species making the attempt to colonize, then it would take just one galaxy wide extinction event to halt their progress... considering the number of galaxies in the universe numbers in the billions or more, then one singular event is not that hard to conceive of...