There is a plant from the North American deserts called the century plant, as it does not bloom for decades after the seed roots, hence the nickname. The plant is like other blooming plants in most respects, in that it spreads seeds, the seeds take root or fail to, but it does not produce seeds annually. Instead, these plants take a long time to grow in the desert before being ready to themselves bloom and close the cycle.
If we consider that there could be alien civilizations existing in our galaxy which have chosen as their space travel meme the propagation of life to lifeless planets, otherwise capable of supporting life, we have an analog to the century plant on a million times longer timescale. Such an alien civilization would essentially be spreading its seeds wherever was appropriate, and then allowing the enormous time to pass in the expectation that some seeds would take place, evolution would happen, intelligence would arise, civilization would dawn and technology would be discovered, leading to a civilization capable of space flight, which might undertake the same mission.
The century plant dies after it spreads it seeds, and surely an alien civilization would not last even a small fraction of the time it takes evolution to generate all the millions of mutations that are required to produce intelligent creatures. They would have to possess some knowledge that their seeding efforts were not doomed to failure; in other words, they would understand all the evolutionary processes that would have to take place in order to produce a successor alien civilization. They would also have to understand the environment of the planet upon which they started a seeding experiment. They would like to know that no planetary upsets were going to happen which would doom life on the planet, although if one is speaking about life, it is hard to imagine a planetary catastrophe that would eliminate all life on a planet. Maybe there would be multiple serious die-offs, from episodes of volcanism or something else, but nothing to eliminate every last living cell.
They would also have to know that the star around which the planet was orbiting would behave itself and not turn into a red giant before the necessary time for evolution had run its course, but that is something easy to understand. Even we on Earth have these estimates. Other problems such as approaching and detonating supernovas would have to be dealt with on a probabilistic basis. A one percent chance of a supernova nearby is not enough to stop them from betting on some potential planet.
Thus, armed with asymptotic technology and as much data about the planet as they could economically gather, they could make the decision on whether to spend the resources to send a seeding probe out. If the analogy with the century plant has any merit, they would send out as many as they could comfortably afford.
We have already talked at length about the preparations that would reasonably be made to do seeding, and some of them, the development of a prototype space probe with seeing capability, would be amortized over all the probes than an alien civilization could send out. Only the first one would have the mountain of expenses associated with developing reliability or regeneration able to handle these long flights. After that, it would just be a matter of copying the first one, and heading it to another solar system.
Think for a minute. It is a wholly different point of view between trying to find a new planet to move your civilization to and trying to seed multiple planets in the expectation that something similar to your civilization would arise on one or more. Which one would an alien civilization choose?
Recall that memes of any sort are not derived from some laws of the universe or figured out as an optimal something or other. They are absolutely arbitrary, as the figuring out of all science and everything else does not tell an alien civilization what to do. They have to decide themselves, and in some posts in this blog is was considered that it would be done during the genetic grand transition, before universal high intelligence became available, and some choices could be made and programmed into the culture by the leaders of the time.
These leaders might be thinking about the survival of the civilization, and use available observations to tell them if there were any life-bearing planets within a reasonable travel distance from their home solar system that could be occupied. At this point in Earth's history, we don't quite know if there would be any or many. If there were none, then the new life on barren planets meme might be the only choice that they could make, other than to die in place, go extinct from one cause or another. If there were some possibilities, perhaps the average alien civilization would shoot for the first of these alternatives.
Some timescales might make sense here. The longest lived alien civilizations, on one solar system, might go on for something like a million years, provided they had all the possible advantages and did all the right things at all the right times. If they moved sometime during that period, they might need to find one new well-equipped solar system every million years, or a thousand worlds in a billion years. Could they find that many? New solar systems are created in abundance with every rotation of the spiral waves in the galaxy, which means that if they can last through a couple of hundred worlds, they might find themselves surrounded by a bevy of new planets. But they would have to wait hundreds of millions of years for life to develop on some new worlds, to make them habitable. So perhaps the number of a thousand worlds is a good estimate of how many they would have to have available to them in order to survive indefinitely.
The fellows who adopt the other strategy for seeding life might decide to do it another way, and become what was called in an earlier post, interstellar nomads. In the series of posts on interstellar nomads, it was contemplated that they could be using this way of life to do seeding, instead of being simply a way for a small number of aliens from a former civilization to continue their existence.
Either way, it seems seeding does not appear to be a ridiculous alternative, and no reason to dismiss it has jumped out. More investigation needs to be done.
No comments:
Post a Comment