Skip to comments.The Fermi Paradox - Are We Alone in the Universe
Posted on 05/19/2004 12:46:40 PM PDT by Conservomax
Fermi's Paradox (i.e. Where are They?):
The story goes that, one day back on the 1940's, a group of atomic scientists, including the famous Enrico Fermi, were sitting around talking, when the subject turned to extraterrestrial life. Fermi is supposed to have then asked, "So? Where is everybody?" What he meant was: If there are all these billions of planets in the universe that are capable of supporting life, and millions of intelligent species out there, then how come none has visited earth? This has come to be known as The Fermi Paradox.
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 a few million years, every star system could be brought under the wing of empire. A few 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?"
Also, if one considers the amount of time the Galaxy has been around (over 10 billion years) and the speed of technological advancement in our own culture, then a more relevant point is where are all the super-advanced alien civilizations. Russian astrophysicist Nikolai Kardashev proposed a useful scheme to classify advanced civilizations, he argues that ET would posses one of three levels of technology. A Type I civilization is similar to our own, one that uses the energy resources of a planet. A Type II civilization would use the energy resources of a star, such as a Dyson sphere. A Type III civilization would employ the energy resources of an entire galaxy. A Type III civilization would be easy to detect, even at vast distances.
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 extraterrestrial 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.
Bracewell-Von Neumann Probes:
While interstellar distances are vast, perhaps to vast to be conquered by living creatures with finite lifetimes, it should be possible for an advanced civilization to construct self-reproducing, autonomous robots to colonize the Galaxy. The idea of self-reproducing automaton was proposed by mathematician John von Neumann in the 1950's. The idea is that a device could 1) perform tasks in the real world and 2) make copies of itself (like bacteria). The fastest, and cheapest, way to explore and learn about the Galaxy is to construct Bracewell-von Neumann probes. A Bracewell-von Neumann probe is simply a payload that is a self-reproducing automaton with an intelligent program (AI) and plans to build more of itself.
Attached to a basic propulsion system, such as a Bussard RamJet (shown above), such a probe could travel between the stars at a very slow pace. When it reaches a target system, it finds suitable material (like asteroids) and makes copies of itself. Growth of the number of probes would occur exponentially and the Galaxy could be explored in 4 million years. While this time span seems long compared to the age of human civilization, remember the Galaxy is over 10 billion years old and any past extraterrestrial civilization could have explored the Galaxy 250 times over.
Thus, the question arises, if it so easy to build Bracewell-Von Neumann probes, and they has been so much time in the past, where are the aliens or at least evidence of their past explorations (old probes). So Fermi Paradox becomes not only where are They, but why can we not hear Them and where are their Bracewell-von Neumann probes?
Possible solutions to Fermi's Paradox fall in the following categories:
In general, solutions to Fermi's paradox come down to either 1) life is difficult to start and evolve (either hard for the process or hard to find the right conditions) or 2) advanced civilizations destroy themselves on short timescales. In other words, this is an important problem to solve in the hope that it is 1 and not 2.
No aliens? I want a DNA test from James Carville! :)
But seriously, thanks for posting. I will read in more detail as soon as I get a chance.
Berserkers: The Galaxy is filled with killer robots looking for signals. ET is keeping low. Problem: where are the berserkers coming after us?
That's the Borg - they aren't here yet.
In the article, the author postulates that if aliens exist we should be overrun by probes by now. The rebuttal to that is that either they have different methods of probing than we have come up with (hey, they're aliens, they think differently), or, like ours would be, theirs are small enough that we have never noticed one (it might not have come close enough to us to be recognized).
Just thought I'd throw that in. I tend to think it is a combination of distance and incomprehensibility that has kept us from detecting/recognizing our neighbors.
We should build a Dyson Sphere. It might take 100,000 years, and it might take more engineering knowhow than we currently would consider possible to attain, but I think we could eventually do it. We're humans - solving impossible problems is what we do best. Bickering over little problems is what we do when we're not solving impossible ones.
Read it before and I think that it's combinations of
Planets With the Right Conditions are Rare
Planetary systems are rare
Habitable zones, proper distance from star for liquid water, are narrow
Galaxy is a dangerous place (gamma-ray bursters, asteroid impacts, etc)
Earth/Moon system is unique (large tides needed for molecular evolution)
Life Is Rare
Life's Genesis is rare
Intelligence/Tool-Making is rare
Language is unique to humans
Technology/Science is not inevitable
AND a third thing, we are still assuming that life is like terrestrial life.
If a being has no eyes, doesn't see the stars, can't imagine another world beyond the limits of his own, why would he try to go beyond it?
And that's an EASY example.
Well of course not, we don't make first contact until 2063...
"The surest sign that intelligent life exists elsewhere in the universe is that it hasn't tried to contact us." -- Calvin
Sometimes the best wisdom comes from a comic strip.
At any rate, perhaps the rest of the universe is still trying to determine if there is actually intelligent life on this planet. One could have difficulty determining that if they were assessing the ape logic found in the major media outlets.
Very good diagrams.
One week the question was "Is there intelligent life on earth?"
On the Friday of that week as I passed it I noticed that someone had scrawled an answer right below the question: "Yes but we're only visiting"
That was my nearest contact with extra-terrestrials
Is it possible that any society smart enough not to destroy itself would be smart enough not to construct Bracewell-von Neumann probes? I'm thinking Star Trek I here, folks.
Oh, and by the way... Once we reach step 2, I'd argue it would be fairly impossible to exterminate ourselves. The window for an intelligent race to annaihilate itself seems rather small for me. BUT! There are other means of population containment besides self-annaihilation. In certain regions of Europe, medieval civilizations avoided overpopulation by the development of a large celibate class. In England, for instance, this led to 3 centuries of peace, and life expectancies that would not again be reached until the 20th century. Fermi seems to believe that population dynamics of intelligent races mimic those of bacteria. (There are arguments for this... It takes only one dissident planet to start populating the galaxy, and this would have to take place among the outer planets -- the most likely to be dissident.)
Because of the distances and energies involved. The Fermi Paradox is pure codswallop IMHO.
Of course another possibility is that a "colonization" took the form of genetic seeding of planets. In that case the answer to Fermi's question would be "You're looking at them".
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