Alien MonolithTo answer the question, “Is it possible to Colonize the Galaxy?”, we need to think about the physics of interstellar travel. Last week we talked about communication, and the thesis that Faster than Light (FTL) communication is a requirement for a meaningful dialog. Receiving radio signals from a technological civilization would certainly change our understanding of the universe, but receiving a message, even if we understand it completely, does not necessarily imply that a meaningful dialog is possible.

Our understanding of the universe limits the number of possibilities for both visiting and communicating with aliens. Either Einstein was correct, and the speed of light is a limiting factor for both, or it’s not. If FTL travel or communication is possible, that doesn’t mean it would be infinitely fast, there might be another limit right behind Lightspeed. Even if FTL science is possible, there is still a small range of possibilities

  • FTL communication is possible, but faster than light travel is impossible or impracticable.
  • FTL communication is possible, but the speed is still limited, and it takes a long time to communicate over interstellar distances.
  • FTL travel is possible, but speed is limited, and it takes years or centuries to cover interstellar distances.
  • If FTL communication is possible, and it’s both cheap and nearly instantaneous, then we are listening on the wrong medium. We’re just not technically advanced enough to discover, much less talk to aliens.
  • If FTL travel is possible, and it’s orders of magnitude faster than the speed of light, and relatively cheap, and there are lots of advanced, technological civilizations out there, at least some of them should have begun to colonize the galaxy. We should be seeing alien spaceships on a frequent basis. We’re back to the Fermi Paradox. Aliens should be here by now, so either those assumptions are false, or there’s another factor that’s keeping us isolated.

The idea that aliens know we’re here, but are keeping quiet, actually makes some sense. It could be that inventing FTL communication or travel is like a cover charge. When we get there, the members of the Galactic Federation will allow us into the club. Or, if we are considered too dangerous and warlike, they will isolate us until we learn to play nice, or exterminate us.

For the moment, let us consider the idea that Einstein has it right, and the speed of light is a practical limit. What are the options in that case?

Science Fiction has had many stories about “Generation Ships,” or “Ark Ships.” The idea is that since interstellar travel takes much longer than a human lifetime, we take a small version of the planet with us. Essentially, a Noah’s Ark for interstellar travel. These are giant spaceships that can travel for hundreds or thousands of years with complete reliability, able to sustain hundreds of generations of humans, along with everything else needed to build a habitable human biosphere on another planet.

Science fiction also offers a variation on this idea, which involves keeping the biological cargo in suspended animation. We’re back to 2001: A Space Odyssey. Such a concept also requires a completely reliable Artificial Intelligence to run things. That didn’t work so well in the movie, but there are many advantages to suspended animation. There is less mass to move since a whole ecosystem, with all its moving parts and complexities doesn’t have to come along for the ride. And the human cargo is saved from decades or centuries of boredom. There are just fewer ways the system can fail.

Even with these advantages, it seems likely it would take a significant part of our planetary resources to build such a ship. No single nation could do it alone. I suspect that the planet itself would have to be in peril, to provide both the motivation and economic cooperation needed to complete the job.

There is another option that’s rarely discussed, robots. If we want to colonize other solar systems, it’s not necessary to send giant spaceships with hundreds or thousands of human passengers, not to mention a complete biosphere to support them. We only need to send the DNA. If fact, it’s not even necessary to send actual DNA, which would be subject to damage over time. What’s needed are the instructions on how to build DNA, along with the intelligence and machinery to construct it from fundamental elements.

Building a new home for humans is not a simple task. Our robot intelligence might find a planet of the correct mass, at the right distance from a suitable sun, but with a primordial atmosphere. The intelligent spaceship would have to terraform the planet in order to make it habitable. The robot could could collect asteroids and rubble from around the system and create a moon to stabilize the new Earth’s axis and climate. Plus, there’s the added benefit of reducing the number of likely mass extinction events.

The point is that there have to hundreds, probably thousands, more “potential” Earths, than there are planets with a biosphere perfectly suited to humans. To have any reasonable chance of colonizing distant solar systems, we have to design our robots to make the best of what they find. The process of preparing a suitable biosphere will take thousands of years. Maybe longer.

Once a basic biosphere has been established, our AI robot would have to direct the evolution of any existing life, both exterminating some dangerous organisms, and creating new forms hospitable to our newly created humans. It would most likely have to make some changes to the human genetic line in order to provide the new humans with the best chance of survival. Every decision would have enormous implications. Our intelligent colony ship would essentially be God for this new Earth.

The great thing about having robots colonize the galaxy is that they only need some machines which can build other machines, along with super intelligence and a very large amount of data about creating stable ecosystems. They don’t have to find duplicate earths, only planets capable of being transformed into suitable worlds. Our AI robot could re-engineer humans to live on marginal planets. As the first humans evolve and gain knowledge, they would alter the planet and eventually control their own destiny.

Robots carrying minimal machinery and lots of data, could have a near infinite lifetime. It’s possible they could seed a new system, get a new generation of human colonists going, and move on to discover another system. It’s a simpler and much more efficient system than trying to transport a huge, intact biosphere across interstellar distances.

If we assume that travel faster than the speed of light is impractical, then the logical assumption is that the first aliens to visit earth will be robots, and will not have the best interests of humans as a prime directive. Unless of course, they were here a very long time ago.

One might ask why, in a galaxy of a few hundred billion stars, the aliens are so intent on coming to Earth at all. It would be as if every vertebrate in North America somehow felt drawn to a particular house in Peoria, Illinois. Are we really that interesting? Seth Shostak


What Will it Take for Humans to Colonize the Milky Way?

Is a Gaian Bottleneck the reason We Haven’t Heard from Aliens?

How Long Would it Take to Colonize the Universe?