Skip to comments.Our Galaxy Should Be Teeming With Civilizations, But Where Are They?
Posted on 10/25/2001 9:13:53 AM PDT by RightWhale
Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right?
It's been a hundred years since Fermi, an icon of physics, was born (and nearly a half-century since he died). He's best remembered for building a working atomic reactor in a squash court. But in 1950, Fermi made a seemingly innocuous lunchtime remark that has caught and held the attention of every SETI researcher since. (How many luncheon quips have you made with similar consequence?)
The remark came while Fermi was discussing with his mealtime mates the possibility that many sophisticated societies populate the Galaxy. They thought it reasonable to assume that we have a lot of cosmic company. But somewhere between one sentence and the next, Fermi's supple brain realized that if this was true, it implied something profound. If there are really a lot of alien societies, then some of them might have spread out.
Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire Galaxy. Within ten million years, every star system could be brought under the wing of empire. Ten million years may sound long, but in fact it's quite short compared with the age of the Galaxy, which is roughly ten thousand million years. Colonization of the Milky Way should be a quick exercise.
So what Fermi immediately realized was that the aliens have had more than enough time to pepper the Galaxy with their presence. But looking around, he didn't see any clear indication that they're out and about. This prompted Fermi to ask what was (to him) an obvious question: "where is everybody?"
This sounds a bit silly at first. The fact that aliens don't seem to be walking our planet apparently implies that there are no extraterrestrials anywhere among the vast tracts of the Galaxy. Many researchers consider this to be a radical conclusion to draw from such a simple observation. Surely there is a straightforward explanation for what has become known as the Fermi Paradox. There must be some way to account for our apparent loneliness in a galaxy that we assume is filled with other clever beings.
A lot of folks have given this thought. The first thing they note is that the Fermi Paradox is a remarkably strong argument. You can quibble about the speed of alien spacecraft, and whether they can move at 1 percent of the speed of light or 10 percent of the speed of light. It doesn't matter. You can argue about how long it would take for a new star colony to spawn colonies of its own. It still doesn't matter. Any halfway reasonable assumption about how fast colonization could take place still ends up with time scales that are profoundly shorter than the age of the Galaxy. It's like having a heated discussion about whether Spanish ships of the 16th century could heave along at two knots or twenty. Either way they could speedily colonize the Americas.
Consequently, scientists in and out of the SETI community have conjured up other arguments to deal with the conflict between the idea that aliens should be everywhere and our failure (so far) to find them. In the 1980s, dozens of papers were published to address the Fermi Paradox. They considered technical and sociological arguments for why the aliens weren't hanging out nearby. Some even insisted that there was no paradox at all: the reason we don't see evidence of extraterrestrials is because there aren't any.
In our next column, we'll delve into some of the more ingenious musings of those who have tried to understand whether, apart from science fiction, galactic empires could really exist, and what implications this may have for SETI.
This is my belief. My corollary is that even if there are aliens wandering around, it doesn't matter--we'll never meet them.
Cigarettes killed them all.
Their race better have a VERY long lifespan then. Why build an interstellar "empire" if you can't live long enough to enjoy it or even administer it? A race could colonize other systems, but since communications and travel are limited by the speed of light at best, political organization of an interstellar "empire" would be very hard or outright impossible. Basically, each system would be its own independent political entity and cultural "petri dish" evolving independently from fellow members of their species in other systems.
Perhaps therin lies the best hope for freedom there is. Just pick up and move to where nobody else is willing to follow you. I don't know how easy it'd be to do so, since there's a lot of variables (access to transport, willingness to leave the homeworld, availability of habitable planets, terraforming, etc.).
Hell, mabye every culture eventually evolves Democrats to muck things up?
Yeah, whatever. No sane person with even a rudimentary knowledge of physics, much less an expert, could possibly believe something this preposterous.
Agreed, totally. Even if the galaxy is uninhabited by other civilizations, when we finally get off this mudball and get out there, we will have to break up into separate self-rule entities. While we might spread out throughout the galaxy in a million years once we get moving, linkages to a central authority would be next to impossible.
I postulate, we just haven't been found yet!
The galaxy isn't all that large compared to the speed of light. The galactic empire part is probably not going to happen, but human occupation of the entire galaxy in a million years is feasible.
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