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.
At first it can be disheartening. But then a sense of optimism can come up, an understanding of a job that needs to be done. We could populate all that wasted space before the universe cools off much more. Of course ultimately even that will come to an end. Even stars go cold eventually. But we could have a busy and fun time for a couple million or billion years.
Actually the authors of Rare Earth argue that simple life forms probably exist throughout the galaxy, but the probability of complex life existing anywhere in the galaxy other than on earth is extremely low. None of the discoveries of extra-solar planets made to date improve the probablitiy of complex extraterrestial life since all extra solar planets found so far are gas giants with either highly elliptical orbits or orbits in the habitable zone. Have you read Rare Earth?
Yes and no. For our kind of life yes. Maybe for a different type completely unknown to us the center of the galaxy would be perfect. Who knows.
Why it destroys itself, or how, shouldn't be much of a stretch for us to imagine given the present course of events...
We are just starting to discover extra solar planets. I am not surprised at all that the giants are discovered first.
You found me out! ROFL!!!
One thing I'd like to point out is SETI. A lot of people are talking about SETI's failure to find anything in 30 years. What most are forgetting is that SETI is only checking a very small percentage of the band width we know can function as carrier waves, only the bandwidth we actually use. Technically it's possible there could be a fairly advanced civilization on the "dark" side of the moon that's been there the whole time but doesn't use the same section of the carrier wave bandwidth we do. Much as I love the spirit of SETI it's actually not a very well designed experiment. There are only two ways SETI could ever prove anything conclusively: if they got a hit, or if they radically increased the scope of the experiment. Of course SETI already gets in more data than it can analyze in a reasonable amount of time, so increasing the scope would also increase the analytical delays. It's entirely possible SETI could realize it got a hit years ago but never analyzed that block.
Apparently you didn't get the memo from God that stated the REAL situation with this. One has to wonder what you did to get bumped from the distribution list, if you were ever on it. But since you obviously weren't intended to be privy to the facts, I can't disclose any more. Sorry.
There is even a bigger problem than that. The galactic noise drowns out any possibility of getting a signal below 1Ghz and the Atmosphere above 10Ghz. So we are "stuck" between those two frequencies. A radio telescope on the far side on the moon would be ideal but I haven't the funds to put one there (at least this year LOL!)
I'm one who thinks the misnamed "Fermi's Paradox" is a serious problem for the hypothesis that there are advanced extraterrestrial civilizations. (I say "misnamed" because the Fermi Question is not a paradox. It's a reductio argument against the view that advanced extraterrestrials exist.)
All it would take is one E.T. civilization in our galaxy to have reached technical sophistication several million years ago. This civilization could send little green explorers out in flying saucers, or build self-replicating robot probes. Either way, assuming the travelers only go v<.1c and supposing that it takes 100,000 years from the time the travelers arrive on the new world to the time a new robot or people vehicle is sent out (a very conservative estimate), the original civilization will have the entire galaxy populated in a little over ten million years.
Consider that the earth is about 4.5 billion years old, and the galaxy itself over ten billion years old. If, in fact, the conditions for the development of technical civilizations in our galaxy really are favorable enough for there to be some E.T.'s around sending radio broadcasts then why hasn't at least one flying saucer made its way to earth by now? Why isn't there at least one robot probe in our vicinity which has detected us?
I am skeptical of the premise of radio SETI, in other words. It's hard to understand the view that there are several advanced E.T. societies around transmitting messages of peace and good will but none have yet managed to show up in our neck of the woods in person or through their robot surrogates. I'm more willing to believe that we are the only technical civilization ever to exist in our galaxy than I am in that hypothesis.
ROTFLMAO!!!!!!!!!!!
Sure I do. Microbial life is probably everywhere.
Nope. There has been ample time, using a drunkard's walk, for every single star in the galaxy to have been visited multiple times. If there are several spacefaring societies, there should be a traffic jam.
Also we should observe their traffic--which we do not.
Finally, I commend the recent book Rare Earth to your attention.
--Boris
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.