It appears possible for an alien world to communicate with its colonies by setting up large microwave transmitters. The transmitters would have to be much larger than what we build on earth, but in space there is no gravity, and a parabolic dish antenna would be easier to build and much lighter in total mass. The transmitter would need a power supply as large as a small research reactor, perhaps a megawatt, which is one thousandth as much as a city power station produces. The receiver would also need a large antenna, and the same space-has-no-gravity argument applies.
The calculations done on this system in a previous post assumed a distance of 10 light years, and no magical gains in processing were necessary. It is not hard to see how the distance could be pushed to 100 light years, with either 100 times the power, or 3.3 times as large transmitting and receiving antennas. It begins to look a bit shaky after this. Note that the reactor power would have to be converted to microwaves, perhaps X-band, and we do not know how to do this except by a large bank of smaller microwave generators. For the purpose of this post, we leave shrinking the number of microwave generators to the aliens, who will have centuries more experience, and will know the perfect way to do it.
The implications that the galaxy can be wired for slow communications between planets has important implications. Before these are considered, a simple question should be asked. Would the alien home world and their colonies have any use for this communications? What would they want to say to each other? Obviously, there is no technology news worth transmitting, and details of life on a colony would hardly be interesting to a planet which is almost identical, and the news would be 10 or 100 years old. Decisions on running a city on the colony would be best left to the city itself, or at most to the colony planet, as if anything required any action whatsoever, waiting 20 or 200 years for an answer doesn’t seem realistic. The lives of citizens run at timescales of days and years, despite the fact that life does not change in its fundamentals and has not changed for many millennia, or even millions of years. So, what is left?
During the period of colonization of the galaxy, when there is a grand strategy for picking which planets will be done each thousand years or so, there is news of the progress of it, and perhaps some coordination on new colonies to be established, where different planets already colonized could each provide some fraction of the resources needed to accomplish whatever colonization tasks a particular planet required.
If colonization takes many centuries to do, or better, the first step involving the home planet’s efforts takes many centuries to do, with several starships traveling from the origin planet to the new colony, coordination would appear to be useful, even if it took ten or a hundred years to do so. There are statistical, unpredicatable events that happen, such as losses from reliability failures or interaction with space debris, and these losses might be made up for in the next ship, if communications were possible. It is hard for us to appreciate a project that might take centuries or millennia to accomplish. The Great Wall of China was built in two periods, with the first starting at 221 BC and the last ending in 1644 AD, when a certain gate in the wall was opened to the Mongols and they passed through it and shortly thereafter took over Beijing. To travel from one end of the Great Wall to the other might have taken a few years. To travel from an origin world to a new colony would be a hundred or a thousand. This is truly hard to conceive of.
After the period of colonization had ended, would there be any use in maintaining the communication network for more millennia or even millions of years? Perhaps maintenance is the key, but not maintenance of equipment, but maintenance of the society itself. Think of the social organization as an entity which runs the planet. A planet, perhaps of 10 billion citizens, living in nearly closed cities, recycling everything possible and extracting replacements for the losses from planetary sources or even interplanetary resources, has to have a very complicated control system. Furthermore, citizens need to behave according to the regulations needed to accomplish the life-supporting tasks of the governance mechanism. Is it possible to have serious breakdowns of this entity, where either the governance fails or some social group fails to act according to the social norms, or some other action occurs which is serious on the level of the planet? If a certain city has a problem, then other cities can lend assistance. But if the social infrastructure of the planet has a problem, who is there to call upon but a different planet? Even if travel takes a hundred years or more, it is slightly conceivable that a call for assistance would be broadcast. Clearly, a society that endures for thousands of year builds up experience on all the types of problems that could ever happen, and how to deal with them. If there are problems so macroscopic that another planet’s assistance is required, then the communications network would be useful, and therefore worth maintaining. This particular question needs to be thought through in more detail, but it is at least not impossible that colonies and the home world would maintain some communications. They might not use it often and thereby prolong the service life of the equipment, but they occasionally would test it and possibly use it for some purposes, since it was there and should be used for verification reasons.
So it is possible that the Milky Way Network could exist, especially during the period of colonization, and in areas where colonization of new solar systems is going on, but even in regions where the home world is ancient, and the colonies are as well. What exactly does that mean for us on Earth?
It means that if we are on a beam line, and we figure out the optimum frequency band and build a huge dish and aim it in the right direction, we might hear their test signals or their default messages, or even some ordinary traffic. Beam lines could be found by looking at habitable planets, and connecting them with a straight line. If we are not on a beam line, this is simply too bad for us, as no interception is possible. If we are on one or more beam lines, then we have to decide if the habitable planets are really habitable in the sense that aliens could have originated there or been colonized there, rather than being the astronomers’ habitable planet which simply is a measure of the sun’s energy flux to the planet. If some beam line passes this test, to the best of our ability to figure it out, we might consider building the dish and receiver necessary to intercept their messages. A small dish, such as we have on earth, would not work. Something larger, in space, would be necessary. This may be within our engineering ability, or just beyond it. If we do hear their messages, and can de-encrypt them, we will have solved the question of whether there is intelligent life on any other planets than Earth. We will know that it exists on at least two, and since the laws of probabilities indicate it would be extremely lucky if we were between the only two inhabited planets other than our own, we would be forced to conclude that the Milky Way was a crowded place. This would be a revolutionary discovery for us to assimilate.
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