The Fermi Paradox - Are We Alone in the Universe

[Conservomax]

Fermi's Paradox

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.

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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:

• They Are Here
  • They Were Here and They Left Evidence
    • UFO's, Ancient Astronauts, Alien Artifacts: all fall under the heading of proposals that aliens are here now (and they call themselves Republicans) or have been here in the recent past. Problem: evidence for aliens is non-existent.
  • They Are Us
    • Humans are the descendents of ancient alien civilizations. Problem: where are the original aliens? Where are all the other alien civilizations
  • Zoo/Interdict Scenario
    • The aliens are here, and they are keeping us in a well designed zoo (cut off from all contact) or there is an interdiction treaty to prevent contact with young races (us). Problem: scenario lacks the ability to be tested. Takes only one ET to break embargo.

• They Exist But Have Not Yet Communicated
  • They Have Not Had Time To Reach Us
    • Speed of light slows communication levels, relativity makes space travel long. ET's message may not have reached us yet. Problem: Galaxy has been around for billions of years, even if one ET civilization formed a few million years before us, the Galaxy would be filled with Bracewell-von Neumann probes.
  • They Are Signaling, But We Do Not Know How To Listen
    • EM radiation, gravity waves, exotic particles are all examples of methods to signal. Problem: they may use methods we have not learned yet, but if there are many civilizations someone would use EM methods.
  • Berserkers
    • The Galaxy is filled with killer robots looking for signals. ET is keeping low. Problem: where are the berserkers coming after us?
  • They Have No Desire To Communicate
    • ET has no interest in conversing with lesser beings. Problem: with millions of possible civilizations, someone would have some curiosity.
  • They Develop Different Mathematics
    • Mathematics is the universal language. But humankind may have a unique system of mathematics that ET cannot understand. Problem: then where are their incomprehensible signals?
  • Catastrophes
    • Civilizations only have a limited lifetime, They are all dead.
      • Overpopulation
      • Nanobots -> Gray Goo Problem
      • Dangerous Particle Physics

• They Do Not Exist
  • We are the First, Life is New to the Galaxy
    • Life is new to the Galaxy, evolution takes time, we are the first civilization. Problem: Sun is average star, if other stars formed a million years ahead of us, then They would be a million years ahead of us in technology.
    

  • 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

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.

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[Calvin Locke]

My theory is that a number of civilizations have come and gone. The last detectable radio transmission passed the
Earth the night before Marconi finally got something working.

And any civilization the managed to pass through the "social consciousness" stage survived long enough to migrate to younger
stars and is smart enough to avoid civilizatoins that produce activists in general, activist judges in
particular, the DNC, and religions that can't quite seem to progress beyond the gutter of the universe (I'll be happy
to re-evaluate after a reformation or two, but I fear our star will go Red Giant first...)

[dangus]

You presume a Type II Dyson sphere. Dyson said what he foreaw was a loose collection of over 100,000 objects traveling on independent orbits. Dyson also predicted a Type III sphere called a ringworld, which would require only the amount of matter of a large asteroid, and yet would capture a significant portion of a star's energy.

Actually, come to think of it, even a handful of solar collectors would technically fit the definition of a Type I Dyson sphere, and that has already been proposed.

[dangus]

>>They have seen the earth and how we behave and have no desire to visit here.<<

I've heard it proposed that we would likely be quarrantined. We are approaching the age of near-light speed travel, which would create the danger of photonic wakes: dangerous for unseen bystanders. But I think the person who brought this up was full of BS...

[Physicist]

Our 12-20 billion year sphere of observation is only .000000000000000000001 to the nth power (or however you phrase it) of the actual size of the universe.

Like babies, we think that what we see is what there is.

What do you mean "we", kiddo? You're a bit late in getting the the playgroup.

As for your assertion that the universe is older than it looks, that contradicts your (correct) assertion that the universe is larger than it looks. The reason the universe looks so small is because it's so young.

[RightWhale]

There are megalithic structures all over the earth as old as 10,000 years, but they are not in good repair. Anything less than megalithic structures would not last even that long. There wouldn't be much left of anything older than that. If something happened to be living here 100,000 years ago and didn't happen to build megalithic structures, it would all be gone back to nature. If we found some fossil bones, we might not recognize them as alien, especially if they were related to us in the first place.

[Calvin Locke]

Lack of "money". It's expensive to travel throughout the Galaxy.

Yeah, I have yet to see one "Altairian" dollar

I can't even find the exhange rate.

[NJ_gent]

"There isn't enough matter in the solar system, outside of mining the sun, to construct one."

Sure there is. Using the materials from the inner planets alone, we could construct a very thing Dyson sphere. Using the materials (minus the hydrogen and helium) from the outlying planets, we could construct a reasonably thick, complete Dyson shell. Wiki had some fairly reasonable calculations about it. Unfortunately, there's that little problem of gravity, the other one about heat, radiation, atmosphere, etc. All of these are impossible problems to conquer along the way.

[RightWhale]

Well, FTL and time travel and all that would be great, but at the moment we have to go with what we know how to do. Think about it, if we knew FTL were possible because we saw somebody doing it, would we not immediately do research to see how it is done? Just knowing somebody is doing it would be a valuable knowledge.

[Oberon]

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.

Eventually, perhaps...but by the time we've solved the problems that stand in the way of building a Dyson sphere, we'll probably have easier, better ways of generating cheap energy than using a Dyson sphere.

[CharacterCounts]

Life Is Rare

Life doesn't have to be rare to answer the paradox. For life to visit other planets it must be intelligent.

Intelligent life is obviously exceedingly rare. One has to go no further than our own planet to observe this fact. If you consider life on earth from the bacteria through humans, the odds against intelligent life developing, even on a hospitable planet like ours, is in excess of a billion to one.

[PoorMuttly]

Well...Shaggy Eel and I are here...and all those Orc thingies we've been eating...

[PoorMuttly]

...do you think I said too much..?!

[RadioAstronomer]

True, but it does something else - I can't remember - perhaps it blocks asteroids or affects the magnetic fields which protect us from radiation. Its something like that.

see post #70

[antiRepublicrat]

Of course another possibility is that a "colonization" took the form of genetic seeding of planets.

Wasn't that a Star Trek Next Generation episode?

[NJ_gent]

"if we knew FTL were possible because we saw somebody doing it, would we not immediately do research to see how it is done?"

NASA's JPL does research on FTL travel and data transmission possibilities. Interesting things have crept up with oddities like quantum entanglement and the like, but nothing's as yet been concrete enough to be considered a breakthrough.

[parsifal]

Thank you for the link. I always thought universe was probably bigger.

And older. I don't get the "younger" part.

parsy, the deep thinker.

[NJ_gent]

"Wasn't that a Star Trek Next Generation episode?"

Season 6, actually: The Chase.

[Physicist]

The reason it looks so small is because the speed of light is finite. From our point of view, the stuff 13.7 billion years out is only just forming. The stuff beyond that hasn't formed yet. If the universe were older than 13.7 billion years, we'd see stuff farther out.

[general_re]

That can't be THE parsy. My, my, where on earth did you go? And did you ever solve your chicken problem? ;)

[PatrickHenry]

One possible explanation for the "no contact" situation isn't listed in the lead article: technological stagnation. An intelligent bunch of aliens could be frozen for millions of years in ancient-Egypt-like societies. Most human societies have been that way. Such societies can be very stable. It tales a wild technological leap to get to where we are. Perhaps that's what's really rare.