Monday, July 13, 2015

Low-hanging Galactic Fruit

In trying to figure out some clues about a grand strategy for colonization that an alien civilization would devise, it might be useful to think about the spectrum of possibilities that awaits them, once they begin moving beyond their own solar system. We are talking about a category 3 civilization, where the categories relate to their desire to colonize other solar systems. Category 1 says never, category 2 says only if we are forced to, and category 3 says that’s our mission in life. We are talking about alien civilizations that are omniscient, in the working definition defined in an earlier post. They have finished science and engineering. But they do not necessarily have from their theories a galactic directory of all planets. That can only be obtained by observation or exploration. They have done the observation, but not the exploration. That’s where we want to focus on in our discussion, as that is the likely point in their long history where they make their grand strategy for colonization. Can we figure out anything at all about such a grand strategy?

The guiding principle is that they would do it as efficiently as possible. Do not forget that the alien civilization was pushed by the availability of resources into a recycling mode, to make these resources last as long as possible. To do recycling to 99.9% or more requires a great discipline, and the members of the civilization would have adopted it. It would be part of their life, from birth to death. And with this constant reminder, it would be only reasonable that they would seek efficiency in colonization.

We can try and understand what the drive for efficiency in colonization would mean about the grand strategy. With a mission to explore and colonize what is habitable in the galaxy, they would also not be trying to procrastinate and dawdle about it. If there is an efficient way to get going, they would do that, rather than wait until forced to, as a civilization of category 2 would do. It is fairly obvious that two planets can promulgate about twice as fast as one. More fully developed colony worlds, more exploration. Space gets in the way here, so fifty fully developed colony worlds will not explore fifty times as fast as one, just a lot more than one.

A pattern of moving out in an expanding sphere might be the locational part of a grand strategy, but leapfrogging some possibilities to go to a more attractive possibility could be another. This is the source of the title of this blog. Would they go further to a better planet, quickly develop it into a clone of the home world, and then later double back to do worlds closer to their origin home planet? In terms of detecting the signatures of starships and home worlds, should we look for long voyages between very specially selected planets, or only short voyages between adjacent star systems? Of course, if they have been doing this for a billion years, they have already done the low-hanging fruit and the less interesting hard to inhabit planets as well. Then we are looking for life signatures on home worlds. If the colonization clock for this alien civilization is still in the early times, we might be looking for the signatures of long trips. A long trip signature might be a little different than a short trip signature. They might want to go faster. And higher speed means more emissions. If 0.01 c was just fine for a 5 light year journey, what about a 1000 light year journey? Going 0.01 c doesn’t look nearly so good. Questions about reliability, on-board supplies, natural decay of seeds even in a cold environment (radiation doesn’t care about temperature), skin erosion, and lots of questions their starship engineers would be considering might mitigate against it.

What exactly would make a planet a low-hanging fruit? If we are considering efficiency of turning this planet into a new home world, we need to consider the resources needed to convert it, the energy needed, the resources and energy that would be readily available on the new planet in pristine form, and the conversion time by whatever process they want to follow. Conversion time might be the big deciding factor. If a planet has oxygen, and our alien civilization needs it, traveling 1000 light years to get to it might be worth the trouble. If they stopped at a neighboring planet without oxygen, seeding it with specially designed seeds for growing oxygen producing plants might require a very long time to get established. Maybe the seed count is enormous, and there would have to be some factories built down on the surface to process minerals dug up to get the carbon needed for the seeds. The factories would have to be robotic, and where to you get all those robots? Ship them in from the home world? That requires more starships, and those used for hauling terra-forming supplies cannot be used for explorations.

Making these types of arguments only provides us with good guesses as to how the alien civilization would build its grand strategy, as the details are completely unknowable to us, at least until after we detect their shipping. But having good guesses as to where to look might help.

The idea that planets with oxygen might be the low-hanging fruit for colonization means that the aliens’ reverence for life might be relevant. Thinking through that in another post indicates that they wouldn’t have any for life-forms on other planets. As far as we know, oxygen is produced by life. If our own science finds out that it is produced otherwise, modifications of this argument would be needed. At this stage in our thinking, it would appear that the grand strategy for a category three alien civilization would be to capture the low-hanging fruit of the galaxy, meaning planets with resources, energy sources, and a good oxygen-containing atmosphere. If they breathe methane, make that a good methane-containing atmosphere. But for the case we know of, the grand strategy says go first to inhabited planets, even if they are far away. By inhabited we mean inhabited by vegetation, either in the oceans or on the land surface. Then build up these into home world clones as soon as possible, and expand to other uninhabited but still habitable ones from there.

How far to go on a single jump is a matter of alien civilization engineering. As noted in the posts on Asymptotic Technology, this does not include magic which violates the laws of nature as we know them. We don’t know too many of them, but the hard sciences and engineering based on hard science, meaning physics and chemistry and their specializations, have been developed on Earth a bit, and we might as well base our thinking on what we know rather than what we fantasize might happen.

Let’s call the original grand strategy the spherical strategy, and the one discussed here, the leap-frogging strategy. The leap-frogging strategy might make no sense if most solar systems have an inhabited planet, up to the level of photosynthesis. That would call for the spherical strategy. We don’t have data yet about the presence of oxygen on even the closest exo-planets, but instruments to detect it are being discussed in Earth astronomy circles as one of the next capabilities to be done. Perhaps it is decades out, which is not far in science, just in our lives. Once we do that, and have figured out also how to detect starship exhaust or some other signature, we can concentrate our attention on fast, long-range ships or slow, short-range ships appropriately.

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