Nearby Black Holes

Currently, it is very hard for Earth astronomers to detect black holes. Black holes are neutron stars which have enough mass to generate a Schwarzschild sphere around them. Neutron stars are stars which have a density like that of an atomic nucleus, except there are simply neutrons there instead of a mixture of neutrons and protons. Neutron stars are not black, meaning some light can get out of them, but for larger ones, it is not much. Consider a neutron star just a little lighter than a black hole. Light emitted at the surface will fall back to the surface unless it is going directly up. In this vertical case, it gets reddened an extreme amount, making it hard to be collected. A slightly less mass neutron star would have a wider cone of light which could escape from the surface, but still it would be strongly reddened and therefore hard to detect. If a neutron star is adding mass, by infall for example, its emission cone gets narrower and narrower, and the photons that do escape get redder and redder. The limit is reached when the cone goes to zero, and then even vertical photons fall back to the surface of the neutron sphere. The highest point a photon can get is called the Schwarzschild sphere of a black hole. Neutron stars are terribly difficult to directly detect for another reason. Any photon which is created even a few neutron radii below the surface is likely to be absorbed before it gets to the surface, so not only does light-bending make them invisible, so does the lack of emission sources anywhere but in the thinnest layer of the surface. Exceptions are those neutron stars which have intense magnetic fields and emit radiation at the poles, and others which rotate rapidly and radiate pulses due to some interaction of the magnetic field and surrounding matter. How many of these mostly undetectable black holes and neutron stars might there be? The only mechanism found so far for generating them is the burn-out of large stars, ranging from 10 to 25 solar masses for neutron stars and more for black holes. A simple table of such stars, showing their lifetimes divided into the age of the galaxy can produce an estimate. One can assume that the number density of these large stars has been the same during the life of the galaxy, or something else that would be higher, as there was earlier more gas to form large stars. This gives a number of the order of a billion neutron stars might exist now, but since they are almost undetectable, the estimate could be far off. Black holes form either from the collapse of even larger stars, or from a neutron star which collects more mass. How many of them exist in the Milky Way? If most neutron stars wind up as black holes, the number could be something like a billion. If the production of large stars in the Milky Way when it was younger was more intense, there might be ten times that. To get some casual estimates, this number can be compared with the number of stars in the Milky Way, but regrettably, that number is quite uncertain as well. Perhaps there are a hundred billion. If the density of neutron stars and black holes together is a tenth that of stars, and the density ratio holds in our part of the galaxy, it means that there might be a black hole or neutron star something like five to ten light years from many solar systems. In some cases, one might be closer than the nearest star. Neutron stars have about the same mass as the sun, and black holes start at perhaps twice the mass of the sun. This means that if one were nearby to a solar system where there lived an advanced civilization, it could be fairly close, perhaps closer than a half lightyear, and still be hardly detectable. If we consider the Earth as an example, if there was a three solar mass black hole at 30000 Astronomical Units out from the sun, it would not affect the solar system much at all, and therefore not be indirectly detectable. Gravitational pull from the black hole would be of the order of a few billionths of that of the sun on the Earth, and not much more on the outer planets. This radius is out in the Oort Belt, whose existence is somewhat controversial, as nothing in the Oort Belt has ever been detected. Its existence is surmised as the source of long-period comets which come hurtling in toward the sun from time to time. A black hole out there could serve as the instigator of the comets as much as having a hidden planet there or just having one icy blob interact with another to change the comet's orbit to an extremely elliptic one that passes near the sun. What would it mean to an alien civilization to have a neutron star or black hole a half-light year from its sun? These objects would certainly be detectable with huge telescopes for the civilization, just as they will be from Earth as soon as we start building them. There are really two different situations here. One is that if the black hole (or neutron star) has planets, it would be a very convenient location for an initial starship to head to. But can a black hole (or neutron star) have planets? Large stars are just as likely or even more likely to have planets than ordinary-sized stars, so just before the star starts its supernova process, the planets will be there. They might be the size of Earth and rocky, or gas giants, or icy mid-sized planets or any other combination. When a supernova goes off, a tremendous amount of mass and energy is emited from the star, and it comes crashing into the planet. What happens? In the first stage of the process, for a rocky planet, the side of the planet facing the star turns incandescent, increasing the pressure almost instantaneously, which starts to blast mass away from itself, towards the star. This process, explosive ablation, builds a barrier between the planet and the supernova so that the ablated material absorbs some of the radiated energy. If some gets through, the ablation process gets more intense, and larger quantities are blown into the barrier. This is a feedback effect, and if the planet is big enough, it might stop itself from being totally vaporized, so that when the supernova explosion process ends, what is left can reform into a planet. It will be in a more elliptic orbit, but that might circularize over some millions of orbits. A gas giant or an icy semi-giant will also have an equivalent process to explosive ablation, but the atmosphere will be torn off and if there is a core, it might be exposed. Exactly what is left depends on the strength of the supernova, the mass of the planet, its initial radius, and a whole lot of very interesting physics. At least some possibility of a planet surviving a supernova exists. Alternatively, a black hole could capture a rogue planet that came near enough to it. Too near, and the black hole would eat it, too far and the planet would continue on past, but at some intermediate range of closest distance, it could get captured. Since the estimate of rogue planets in the Milky Way exceeds the number of stars, this is not terribly unlikely. Thus, if the alien civilization was quite fortunate, it might have a black star or neutron star reasonably nearby and there might also be a solar system of sorts there as well. It seems beyond doubt to assume they would make that their first destination after they had explored their own solar system's planets, and any solar system on a binary companion to their own star. This would be a learning experience and might eliminate the need for a very chancy shot at a solar system a hundred or two lightyears away. The other situation is where there are no planets, and then the alien civilization would have to build a observatory to orbit the black hole, which is a large undertaking. They might prefer to go to the nearest attractive solar system.

Choosing Colony Planets

An alien civilization with a philosophy of life requiring it to spread and disperse life throughout the galaxy, as far as it can, would need to be very circumspect about where to send a seedship. This adventure would require a great amount of effort from the civilization, and perhaps a good fraction of the resources available to it. On Earth, we have not even begun to figure out how this might be done, but we can assure ourselves this is not going to be easy for any civilization. As little would be left to chance as possible.

If we ask ourselves about the possibility of our civilization encountering another one, knowing where they would likely be is a critical question. They start on their origin planet, but then where do they go? We have learned over the last decade or two that there are huge numbers of exo-planets in the galaxy, but of these, which ones might be even initial candidates for an alien civilization's colonies? What are the characteristics of a possible colony planet? If we know that, then we can concentrate our search for alien life, or rather alien civilization, on that class of planet, and spend less on others.

What we cannot assume is that they will only go to other planets which have already originated life. If their philosophy and reason for continuing their existence is to spread life throughout the galaxy, an origin planet would be low on their list – it already has life and there is no need to go there and seed it. That would be superfluous. Instead, they would want to go where there is no life and is not likely to be if the planet is left to itself. Not just any planet would do. There are certainly some detailed criteria for a reasonably nearby planet, within a hundred or two light years, to even be considered as a possibility.

Many planets might only support the alien civilization itself, and not some ecology of plants, animals, microbes or whatever on it.  Their mandate is to spread life, but if the only way that can be done is to establish a colony, then that is the solution to the lack of planets which might be harbors for primitive life.  The alien civilization can set up colonies in many places, but needs to discriminate as to what distinguishes one possibility from another, as far as spreading life goes.  

One dominant aspect of the choice is sustainability. Sustainability means, for some particular alien species or collection of them, the ability to live for a very long period, measured in lifetimes, on the resources and energy located near and accessible to them. It includes the idea that the population should be able to grow up to some minimum value and still live there for that long period. It is about resources existing on the planet, near the surface, but also about being able to extract enough materials to make an energy source that produces much more energy than all the energy needed to collect and process the materials used in the energy generation and distribution process. There must be enough surplus energy for the other half of the problem, providing all the components, such as habitat and food, needed to sustain the new alien population.

The colony starts out with only the equipment that can be carried on the seedship. The development of the colony would consist of several preliminary stages before the uniform growth stage expands the colony up to the desired population. The first stage involves the landing of whatever is necessary to initiate power production with a minimally sized power reactor, create a habitat, and locate and start to mine and process all necessary mineral deposits. A central manufacturing complex would need to be created that can produce, from the ores found, all the specialized items needed for all the operations of the civilization.

Control of this process is not so critical. Can this be done in an automated fashion, or is it necessary to spend time in orbit, gestating the first generation of aliens, before sending them down with the initial lander? Whether the seeding operation is under AI control or under alien control, much the same steps have to be done. The principal difference is that habitats need to be made for the alien landing party, or some additional manufacturing facilities need to be made to enable expansion of the AI capability.

The question of sustainability is not easy to calculate in advance. Yet this is what an alien civilization must do before attempting to spread its population to a new planet or satellite in a distant solar system. They must make an estimate of whether or not a colony could survive on an exoplanet before taking the extreme expense of sending a seedship there The question is not just can the colony survive for a while, but survive and build a large civilization on the planet. The ultimate question involves the possibility that an alien colony, on a colony planet, could create a civilization large enough to send out its own seedship. If the colony planet was a dead-end, without enough resources for the civilization to grow large enough for the project of going out yet further to another colony planet, it should not be chosen.

The calculation depends on what goes along with the seedship. How much energy does it carry to support the transition from nothingness on the planet to a viable colony? Before this is used up, a seedship must arrange for native energy sources on the planet. This might seem to mean a uranium mine, but the uranium metal is actually a small part of what is needed to build an energy-producing fission reactor. Some parts for the first reactor might come from the ship, and this means that sustainability in energy is going to be developed in stages. The energy from the first reactor would need to be deployed toward a variety of tasks.

Total sustainability means that all mandatory mineral resources are present in the planet's crust, easily accessible, and with not too large a cost in transporting them from their mining site to the central location where the colony's initial population will be centered. For an alien civilization attempting to create a very credible and accurate estimate of this, which they would need before a launch, they would have to first collect all possible information about the planet and the solar system it is located in. The only way to do this from their planet is to build huge telescopes, and it also means asymptotic technology as far as planet formation goes, i.e. having geology completely understood, from the time of the gas cloud through all the changes that go on with the crust of the planet. They would need to be able to tell from the spectrum of the star what the gas cloud that created it contained, as for different elements and the relative concentrations of each.

At this point in Earth science, we have not attempted to make any such calculations, and so we don't really know if it is possible, or how accurate it might be. The accuracy is likely a function of the age of the star, as mixing will take place over its history, and the origination elements will also be burned up as they go deeper into the star's core. Light comes from the star's corona, where elements will linger the longest and where transmutation would be slowest.

Data is also available from the spectrum of the planet itself, where it is simply the reflected spectrum of the parent star. This might tell what was in the atmosphere, and what the large areas of the surface have, to a degree. Reflection spectroscopy is necessarily more difficult that emission spectroscopy, but if the telescope is large enough to portray the planet across many pixels, then some information might be gained from each one. Planets rotate, but that should not interfere with the data collection, once the images start coming in. A telescope of large size, perhaps ten kilometers or more in aperature, would be needed.

Information about the nature of the gas cloud that formed the target exo-planet might be gained also by looking at the other planets of the solar system containing it. A gas cloud which undergoes the great transformation from a rotating self-gravitating glob of dust and gas into a proto-star and spinning disk would also have undergone much diffusion, and this implies that at the radius where the target exo-planet condenses there would be some distribution of elements, but at the radii where other planets condense, there would be a different one, and knowing each of them helps the alien scientists to determine the larger picture of the composition and evolution of the cloud.

One kink in this process is that planets don't necessarily stay at the radius where they condense. The effect of the largest planet or the largest few planets might, in some instances, drive a smaller planet to a different orbital radius. The largest planets might also mutually share angular momentum, and drift to different radii as well. Can this be determined from telescopic observations so that the data from all of the planets can be put to use? A good question, and one we on Earth have not begun to fathom.

None of the scientific steps needed seem to be impossible, even from the viewpoint we have now, with our very limited science. An alien civilization a few hundred years further in science than ours should be able to accomplish them, as far as it is possible. Once this mass of data has been collected, perhaps over a century of observation, the estimation of which visible planet would be best to seed can be done.

Affluence in Two Eras of an Alien Civilization

Recall, for reference, that the early history of an alien civilization is divided into eras based on technological change. Some creature on an origin planet evolves intelligence and manipulative skill, and begins to use objects as tools, such as rocks, sticks, fire, and possibly others. This makes the brain grow, and that species is on the road to having a civilization.

On Earth, this early era is called the Stone Age, but that may be because only stone has lasted for the long period of time since this era began. In this blog, eras are divided by what has been labeled grand transformations, as technology completely reworks the civilization and causes most aspects to adapt to it. Provided the planet has animals, the next phase would be hunting in packs or groups, which give rise to the need for communication, and language results, which also makes the brain grow. They would be developing tools for hunting, and for many other tasks as well. Clay or some other formable material might be used here. There is no mandatory ordering of tasks, as one does not depend on the other. Hunting weapons can be developed without having clay pots. This era might be called the Hunting Weapon Era, and much technology gets developed during this period, as the species has been getting smarter and smarter, and more options will be visualized.

After that, assuming climate is reasonably benign and evolution has been doing what it does in the plant kingdom, there would be an Agricultural Grand Transformation. This is where agricultural tools are developed, and the nomadic species, slowly and gradually, settles down so that some of them live in permanent settlements. These tools would be adapted to whatever plants and crops are first conquered by the species, and this might vary by location on the planet. Different areas should have quite different potential crops, as the alien species adapts wild crops to ones which can be reliably grown.

The next era occurs after another transformation happens, the Industrial. Sources of energy are tapped in this era, starting with wind and water if they are available on the planet, and biomass used with fire in a controlled sense. There would likely have been the use of fire for heating of dwellings and for metal working, and the next step is to use it for other purposes. If there are surface quantities of hydrocarbons, they might be used as well. The first engines might be developed to substitute for wind and water power in areas where they are not available and biomass is.

The Industrial Era gives way to the Electronics Era, which runs all the way from the first development of electical communication up through robotics and automation. It depends on the energy sources of the Industrial Era and must therefore come later. Following that the Genetic Grand Transformaion happens, which must also be even later, as it depends on a large amount of computational power being available.

Affluence can be a corrosive influence during these two intermediate eras, the industrial and the electronics, but the bad effects happen in two different ways. It is generated as technology ramps up productivity, and there soon appear many goods, starting with agricultural ones, but soon moving into a panoply of goods satisfying other needs of the members of the civilization. Since any society in a primitive agricultural situation is worried about population growth outrunning agricultural production, with an additional concern possibly arising because of weather or climate changes, the motivation to continue to work in an affluent period would be diminished. If that reduction spreads to the groups which develop technology, the growth rate slows and it might even stop. This represents a potential halt to this civilization's advance to space-faring.

During the electronics era, a second aspect of affluence might set in. Prior to the Genetics Grand Transformation, there might be no ability within the society to improve the genetic mix. This result has been titled idiocracy, and refers to a differential reduction in the per capita intelligence in the civilization. Again, this would permeate all parts of society, including that sector which produces genetic advances. If it stops for this reason, or for a combination of this and the previous reason, technology never reaches the starship level.

How could an advanced alien civilization not notice that this was happening, and do something about it? One possibility is there are no measures in the civilization to measure motivation or average intelligence. This needs to be combined with the gradualness of these changes. The civilization would have no alarm bells going off, only a slight sense that things were deteriorating. And there are so many other things that happen in a society under rapid technological change, that these effects might escape notice completely.

Another possible answer to this is to ask if life in an alien civilization in these two eras will be calm and coordinated or chaotic and divisive? Calmness would come when basic societal questions have been answered, such as what political and economic arrangements should be in place, what goals the civilization should adopt, how should children be educated, and more. At least in the early part of these two eras, what might be called the social aspect of the grand transformation sequence will not have been worked out. There will be a period during economics, politics, education, and psychology become real sciences, with proper definitions, theories, and deductions. But that period may be delayed for various reasons, such as factionalism based on location, background, profession or other divisions. They will also be delayed until what might be called the neurological revolution takes place, and provides the society with a complete explanation of how the brain works. Thus, these two eras may be so disruptive, in the area of social arrangements, that there is no chance that the two ill effects of affluence are even noticed and certainly paid the proper attention.

One way to summarize this is to say that the side effects of affluence, which is the successful application of technology to the problems of the alien civilization such as the provision of food, shelter and other necessities, overwhelm it and cause the rate of progress in technology to gradually slide lower and lower, and the progress itself becomes more and more inconsequential in the innovations it comes up with. This means that the alien civilization will never get to star travel, and never get to visiting Earth.

Colonizing Half-Hot Planets

A half-hot planet is one which is in a close orbit to its star, is tidally locked, and is small enough to not have an atmosphere. Without an atmosphere, the only way heat can come from the side facing the star to the other side is by conduction through the body of the planet, which is bound to be slow. This would allow the side facing away from the star to radiate away a lot of its heat, and be cold. Thus the planet would be half hot and half cold. 

A recent post suggested aliens might migrate to a frozen world, one distant from its star, where the temperature is well below that of the outer edge of the so-called “habitable zone”, which is a poor name for the zone where water can be a liquid. The idea is that with enough technology, the alien colonists do not need solar photons to support their civilization, but can instead mine uranium and low-atomic-number elements useful for fusion. If the planet has enough of those, and the costs of mining it are small compared to the energy it would produce, including all the processing and everything else connected with power generation, the colonists can simply live under the surface in a comfortable environment, while they mined from one place or another all the minerals needed to support a good living standard.

These frozen planets don't have to be planets. A frozen moon would work just as well. As long as the planet doesn't create a terrible environment around itself, from radiation or something else, a moon would do just nicely.

Another thing to consider is that they don't have to be frozen at all. They can be habitable zone planets or moons, but too small to maintain an atmosphere. They cannot be too hot, as the temperature under the surface would be above tolerable temperatures, and this means there would be refrigeration needed for the living conditions, and perhaps also for all the mines. For too hot a planet, this would certainly mean it was unusable. Where exactly would be the average temperature that would make them intolerable is not so easy to determine, but it couldn't be too high.

There is one exception to that: half-hot worlds. In our solar system, we almost have one of these gems: Mercury. Mercury is phase-locked, but not 1:1, but 3:2. Mercury does not keep one face toward the sun at all times, but gradually rotates. If it were phase-locked at 1:1, like the moon is to the Earth, it might be a candidate.

One nice, somewhat speculative, thing is that the dust cloud which forms a solar system might have some differences in the mineral content of different planets, and even some basic trend. It could be that heavier atoms are more populous, relatively, on inner planets. It is not hard to imaging that dust collects like or similar molecules, and some dust grains collect more uranium and thorium than others, and then drift inwards, relative to lighter ones, such as calcium and sodium. When planets get around to condensing, this would mean that there would be more fissionable elements on inner planets, and in fact the most on the innermost planets, including the ones so close that they get phase-locked at 1:1.

In order to make this story complete, the planet would have to be large enough to stay molten after formation, so that the iron-like elements could sink to the center, leaving everything else to condense elsewhere, such as near the surface at a depth suitable for mining. Now the stage is set for an alien starship to land on the cold side, and begin to mine, both for minerals and for living spaces. Lots of other constraints might pop up, such as there being few quakes, strong enough rock to support mining, and so on. There would certainly be multiple more constraints, and it might be interesting to try and think up a list someday, but the main point is that phase-locked, 1:1 only, planets might be excellent places for an alien civilization to spread to.

These planets give off no signature of life, and except for some other alien civilization who was visiting or inhabiting the same solar system, the colonizers would be undetectable. An orbiting ship sent by the original inhabitants of the solar system might see piles of spoil from the mining, or the relic of an old starship, provided it had very good optics.

Now we have an interesting situation at hand. If the idea of living without the use of solar photons works, and mineral wealth alone is enough to make a planet colonizable, there could be lots of alien colonies, perhaps at a density of more than one per ten solar systems. All of them would be undetectable, no matter how hard a second alien civilization in a nearby solar system tried. The only way to find them would be to go to the solar system where they were, and spend a good amount of time scanning the surfaces very carefully, covering every large moon and every small planet not in the too-hot zone but including all the phase-locked ones.

If a colonizer didn't want to be detected, it might be possible to disguise the few local signatures of their presence, so that even this visiting starship would never know they were there. This would involve spreading out the spoils instead of leaving it in an artificial pile, dismantling the starship they arrived in and bringing the pieces underground, and building nothing on the surface outside of a few sensors. There would be wheel tracks from the vehicles used to explore the surface and look for new mining sites, and for transporting the processed minerals back to the home mine, but balloon tires might make this hard to see as well.

The upshot of all this is that the Milky Way might have a huge number of inhabited planets, and we will never know about them unless they choose to inform us. Instead of having only a very few origin planets, which are planets able to originate life and support it while it evolves to having an intelligent creature on it, there might be underground alien colonies almost anywhere there is a suitable planet. These planets and moons probably number in the billions. The age of the galaxy is of the order of 10 or so billion years, so exponential growth might have happened, and aliens are everywhere, just invisible to us.

Vulnerabilities of Population Reduction

There are the obvious ones, which relate to medium scale disasters that could annihilate a single arcology, and if an alien civilization concentrated its population in one, because they were so reduced in population that's all that was needed, it would mean the end of them. There should not be any surprises left in their solar system, meaning they know where all the asteroids are and their orbits, they know where all the subterranean faults are, they understand the risk of tsunamis and don't take that risk, and the same for anything else that happens on their planet, like hurricanes. With no surprises left, and a choice about where to site their single arcology, is there really any vulnerability?

Obviously, if they didn't know these things, it would be premature to reduce population to that level, so for the sake of the argument, figure they do know them and there is no geology left undone. On the psychology side, is there any risk in the slightest degree from one of them becoming psychopathic, and attempting to sabotage an essential system? Again, they are long past asymptotic technology, which includes psychology, so this is not really possible. Furthermore, the genetics grand transformation has given them all good genes and they also understand how to raise youngsters to be stable contributors to the society. They have to go way back to find in their ancient history a time when there was war and dissent, as every alien is rational and logical, and politics is a solid science now, so no reputable alien could raise objections to the way things are done. Technology simply brings calmness to everything it touches. Thus, an alien who had a passing thought about being a saboteur would simply recall that there are no political systems better than the one they have, maybe for tens of thousands of years, and as far as there still exists the abstract concept of justice, they have it.

There would be robots to fill all appropriate roles, and intellos, the biological equivalent of a robot, filling ones where they would be more efficient. Someone eons ago would have figured out how to keep everyone busy and interested, in who knows what, so there would not be any bored malcontents. Technology simply solves problems, one after another, until there are no more. If an alien civilization gets to this state, they can stay in it for as many thousands of years as they want, providing resources are sufficient and their star doesn't get nasty.

It would be hard for them to think of any vulnerabilities they have, or might have in the next millennia, as they have solved those problems already, except for one.

Aliens.

Not the aliens themselves, but aliens of a different sort from a different solar system. Aliens 1 and aliens 2, for convenience. If aliens 2 began traveling in space before they had reached asymptotic technology, or made the deliberate choice to avoid the calming effect it has, they might be going to another solar system with an open mind about annihilating whatever was living there and taking over the planet. This assumes there are two planets with life on them at some reasonably close distance, which could be unlikely or likely – we don't quite know that yet. So aliens 1 might be aware that there are other solar systems nearby them with planets which could have given rise to life, and they were old enough to have evolved a civilization.

One question we haven't resolved yet is could one alien civilization detect another, and how many light years away could this be done. If the answer to the question is that it would be too impractical to do this, or the engineering of the sensors to scan all the solar systems around them cannot be done, meaning there is some limit to what can be detected that we on Earth haven't figured out, and the aliens 1 have figured it out and there is no way around the limit, then they have an indeterminate risk. No telescope, no matter how big, can see finely enough to pinpont the signature of an advanced civilization, and certainly not enough to tell what stage it is in.

This means that the High Council of Alien World 1 can be sitting around thinking of how low a population they want to design for, and they have no way of determining if another alien civilization, aliens 2, is nearby and if they are going to be totally peaceful, or if they mastered space flight before mastering their own psychology, politics, economics, and a few other topics. And they have only their own history to guide them. They got super peaceful and would certainly not try and take over another civilization's world, but their ancient, ancient history says they weren't always this way. And they see a way that star travel could have been invented early on, if there was some motivation to steer technology development that way.

Naturally, they can come up with a master list of every way some alien 2 civilization could try and displace them from their own planet, and from this list, look for ways where having a low population, concentrated in one arcology at the extreme, would make them more vulnerable. Their first conclusion would be that it is very difficult to undertake such a offensive mission, and probably no alien civilization would want to spend that much resources on doing it. Then they might consult the alien 1 who was the most interested in ancient history, and ask him if any faction in ancient alien world 1 had ever chosen to spend some large fraction of their resouces on attacking another faction in a different region. If their history is anything like Earth's, the answer is: most of them did.

Perhaps there is something inevitable in the evolution of thinking beings that forces them through a period of time in which military adventures dominate their history. Or perhaps only a few worlds have such an period. But, if aliens 1 decide that somewhere in the near parts of the galaxy, aliens 2 are building some armada pointing in their direction, then they have a completely new basis for deciding on how much population they want to have. 

Imagining the Goals of an Alien Civilization

It is much easier to imagine some aspects of alien society, such as their energy sources, than other aspects, such as their goals, because we have on Earth made some progress in understanding the possible sources of energy and can make some good guesses as to what might exist in a more advanced society. But with respect to social goals, our technology is very primitive. We hardly understand anything about societies and their goals; even the basis for this technology or scientific knowledge is vague and undeveloped. We have some observations, but nothing equivalent of Newton's law has been figured out yet. Just to appreciate the difficulty involved, think of asking someone in Columbus' time about energy, after explaining the concept to him. He might answer there was wind power, and that's about all. A person who had some education involving ancient Greek science and who had heard of Hero of Alexandria's aeolipile might add steam power, which comes from fire. There would be no way that such a person could estimate what energy usage would look like five hundred years later, or a thousand.

On the other hand, we have some confidence now in understanding electromagnetic energy, kinetic energy, chemical energy, equation of state energy such as compression, and nuclear energy, along with the many ways they exist in nature and how they can be harnessed and converted. A person on Earth today might be able to do a good job in describing the use of energy, and might even be able to imagine how energy might be used in the far future. And if we subscribe to the concept of societal convergence, meaning technology drives society and since technology is the same no matter what planet you live on, all sufficiently advanced societies will have similar features, and therefore what this person imagines for Earth five hunderd years from now would be quite insightful as to what a similarly advanced alien civilization might be doing.

We are in the Columbus era stage of understanding neurology, politics, governance, societal arrangements and whatever else relate to the goals of an alien civilization. We would make grave mis-assumptions to try and use what we think are the goals of Earth's various societies, current and historical, as possible goals of an alien civilization.

Some goals that might pop up from the study of Earth societies' history include empire expansion, maintenance of the existing power structure and factionalization, development of profitable trade connections and routes, collection of items of universal value such as gold, the pursuit of scientific progress and technology, revenge or hatred directed toward some group, usage of a particular economic system, the spread of medical technology to various factions, and so on. These are goals which are appropriate, if at all, for a single planet. Ones which relate to multiple planets might be the expansion of life to dead planets, resettling on other planets as an insurance policy against catastrophes or other events which eliminate life on the home world, and a few others.

Our knowledge of energy and astronomy enable us to realize that some of the one-world goals are ineffectual for a multi-solar system civilization. Each planet of the civilization is almost totally isolated with respect to transportation and communication, not absolutely, but almost totally, by the distances between different solar systems and the huge amounts of energy needed to move anything from one civilization to another. Some minimal communication might be attempted between two solar systems which are not too far from one another, but little can be done with simple information transfer with no transport to implement any agreements, requests, or orders from one planet to another.

An alien civilization which is somehow frozen in its level of technology at something like what Earth has now might also have its goals be chosen from the ones listed above, but technology does not plateau easily. It proceeds forward to the asymptotic conclusion or the society degenerates. So at the very least, we can say that multi-planet civilizations do not have empire-building as their goal, nor the development of trade routes, collection of items to be brought from one solar system to another, and perhaps more.

After an alien civilization moves through its technological development of electronics, robotics, and artificial intelligence, the next area it encounters is genetics. The genetic revolution will overwhelm the electronics revolution, and the concept of factionalization, based on legacy concepts of genetics, local origins, language preferences and so on, will drift away as good genes are made available to all members of future generations beyond some point in time. Technology has shown cost reductions in the electronics phase of development, and when this wave passes genetics, there will be little reason to suspect that good genes would not be universally available.

The same wave of technology would also pass through the quasi-sciences of politics and economics, transforming them into fact-based sciences and enabling an alien society to have wise political structures and economic arrangements. The idea of an alien society having a goal of enforcing some legacy economic system on its members seems a little ridiculous; the optimal system would be known and used everywhere. Why would any region or goup want to use antiquated systems when better ones were instantly available?

For one-planet goals, the one which passes through the filter of advanced society might be the preservation of the civilization via wise use of resources, and the expansion of it to other appropriate planets. The other one is the preservation of life in general on the planet, but more importantly of spreading it to other planets. These are quite dissimilar goals in their effect on the civilization, even though they both originate from the abstraction of the goals of life across all species. There is no reason that both of them could not be accepted and acted upon by any particular alien civilization, except for the cost in resources they both have. If it is true that civilization can establish itself on a much different class of planets that life can evolve upon, it is fair to say that they operate almost independently.

It does not seem possible to extrapolate from goals of Earth societies, current and recent, to goals of a civilization with more advanced technology, by a few centuries of progress. The only way forward is to look for the simplest possible ones, those which derive from the nature of life. Perhaps some others can be found with a different approach, and that is certainly an interesting avenue to follow.