Friday, July 31, 2015

Population Limits on Alien Worlds

Perhaps it is possible to get a limit on how many aliens might live on each of their home worlds and colonies. What would limit the number? It might be standing room. It is hard to imagine a world in which aliens were packed so closely together they had a floor space problem. If the alien civilization were on a truly wretched planet, with only one smallish island to live on, this limit might be the right one. If they lived on a planet that orbited just a few inches inside the habitable zone, the only living space might be a small area not covered by glaciers. If they were on the other edge of the habitable zone, it might be the area in a polar crater that was cool enough to survive in. Other situations where the area available for living might be small exist. Let’s assume it is not the case, and see what else could limit population.

It might be resources. On a scarcity planet, there might be a limit based on how much they have been able to put into the recycling loop and how much they are leaving for the coming generations. Perhaps they impose some limit on themselves, so the planet’s resources will not be exhausted until the far future, maybe when some other event is predicted to happen, like the hot star they are orbiting gets a little too hot for comfort. Are there others?

Let’s not forget about temperature. Aliens use energy, which always degrades to heat, which in turn raises the temperature of the planet. How much energy could they use and still not affect the temperature adversely? This is a complicated question, relating to the type of atmosphere they have and how would it radiate additional heat. The atmosphere is already radiating just as much heat on the average as it receives from the star, and upping the total it has to radiate means it would have to be a bit hotter, and in fact, the different levels of the atmosphere would be affected, all the way down to the surface, which would also serve as a radiator and a heat sink. Sounds like a tough problem, which means it is time to wave hands around and say the answer.

Let’s see how many aliens could live on a world and only add 0.1% to the total heat absorbed, and radiated, from their sun. Our sun is an example, and it dumps about 100,000 TW onto the earth. One guess would be to assume that the average alien consumes 2 kW. This is roughly household consumption in the United States, averaged over days and years. Maybe after a millennium of energy efficiency work it would be less. Maybe if you added in all the additional power that recycling needs, it would be more. Maybe we should increase it to take into account industrial uses, and transportation uses. So, if we use 10 kW as the average society-wide alien energy use, this is likely to be in the ball park, by which we mean a factor of ten or so. The number of aliens this comes out to be is 10 billion. This may not be the factor which limits the population on an alien home world or colony. On a very dim red dwarf star's planets, this might have to be rethought.

Let’s return to land area and see how much land a population of 10 billion would need. Remember that aliens, in order to conserve resources for lots of millennia of existence, must recycle quite seriously, 99.9% on an annual basis or something like that. This means they live in nearly closed cities. If we give each alien a very nice accommodation of 200 square meters for living space, and four more times that for industrial space, common space and thoroughfares, the whole population of 10 billion would need 10 million square kilometers. If the closed city had 100 stories, to assume a nice round number, the cities would have a total footprint of 100,000 square kilometers. The land area of the Earth is of the order of 100 million square kilometers (closer to 150 but Earth isn’t the alien planet anyway), so this means about 0.1% of the land area would be used for urban occupation, and that would be all. Everything gets done in the cities where recycling is that high. Little interaction with the rest of the land is necessary.

Thus, land use is in rough agreement with the population limit of 10 billion. If we assume that each alien uses 10,000 kg of materials, covering everything within the boundary of the city, then the total is only 100 trillion kg, compared to the Earth’s mass of about 10,000,000,000,000 trillion kg. Just scratching the surface, so to speak. If they lose out of their recycling system 0.1% of their total infrastructure mass per year, this means that 100 billion kg is lost each year, and over a thousand years 100 trillion kg. Both static use of materials to build the infrastructure and dynamic use from recycling losses are no more of a limit that heat from power plants. Even after a million years, gross material weight is not a problem. Land for cities is the key factor. Specific materials could be a problem, if there is some material which has a high loss rate and is relatively scarce. This bears further evaluation, but for now, land is what seems to be setting the limit.

This extremely crude set of calculations helps us form a picture of what an alien world might look like. If we assume they divide their population up into a thousand cities of 10 million people each, then one city would be 10 km on a side, 100 stories high. Perhaps some would be underwater, assuming they have an ocean or two, some would be in the mountains, some would be on the shorelines, some would be in the heartland of the continents, and perhaps even some would be floating. A floating city would have different dimensions due to the need for buoyancy, and probably much smaller than the other cities, but it is possible to think of a closed city on the surface of a large lake or the oceans.

We are also talking about alien cities built after millennia of existence, and after having reached the limits on engineering knowhow, and having experienced disasters and engineering oversights, and catastrophes of all kinds that their particular world might throw at them. If the planet has earthquakes, it would be certain that the city would have protection measures between it and the bedrock. If the planet has tsunamis, there would be adequate barriers on the shore side of any city built in these areas. And so forth. Insurance would be unnecessary after a few thousand years of figuring out the planet’s potential for catastrophe and how to mitigate it.

Energy stations have not been mentioned, except to check that the total energy is tolerable from a heat point of view. Perhaps these would be built separately, and perhaps redundantly. Designing a fusion power plant, if that is what they would use, is not quite possible for us, although we have high hopes for it in certain technological quarters of the science and engineering community. Neither has the source of energy, such as deuterium, been considered in the calculations here. This might deserve another post.

Thursday, July 30, 2015

Tapping in on the Milky Way Network

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.

Wednesday, July 29, 2015

Solo Planets

Colonizing a planet probably costs an alien civilization a lot of money, in whatever measure they use to regulate their economy. It means a commitment of valuable resources that will leave the recycling loop, probably permanently, as if a ship is built, stripping it down and reusing the parts might well be done in space, rather than by dropping them down to the planet’s surface. It means energy will be expended in addition to the energy used to power the civilization. People or robots or intellos will devote their time to the task, instead of to the tasks of running the cities.

Both category 0 and category 1 alien civilizations have as one of their memes to colonize the galaxy, and both are looking for planets that are suitable. Both of them would like to do as many planets as possible within some time frame and with the minimum amount of resources needed. Alien civilizations learn early, within a few millennia, how to be efficient and how important it is to minimize waste and unrecyclable consumption. Otherwise they go out of business. Thus, a colonizer is trying to do the colonization of a planet as inexpensively as possible.

Some planets obviously will need much more expense than others. We call planets, sweet spot planets, if they are very close to the desired attributes of the final design for a colony. Some attributes are unchangeable, such as surface gravity, others are malleable, such as the ecology. Of the malleable ones, some take aeons to fix, which is no problem, others may take a comparatively short time, such as cleaning out an area of a hundred or so asteroids which have the potential to impact the target planet within a million years or so.

There is one other unique case that the colonizers will notice. What do they do when they find a planet which will indisputably evolve into a home world with creatures just like the colonizers, or rather, just like the colonizers were before they doctored up their own genes to improve themselves. They don’t have to do anything to it, as it will already become what they would have wanted it to. For zero expense, they achieve the same result.

They could look at their knowledge of the evolution of planets, just like their home world or very similar, and state when the various transitions will occur in the unassisted evolution of the planet. They know what will happen, and probabilistically speaking when it will, as probabilistic events are outside their omniscience. They would know a distribution of times for each of them to happen. They have a choice to make: try and speed up the stages of evolution on the planet, or use their resources on another planet that probably wouldn’t develop life or intelligent life, and make it happen there. If they can cut a hundred million years out of the evolutionary process, perhaps their decision will go one way. If they can cut only 10 million years out, perhaps another way. If they can cut a billion years out, yet a third way. Since we have not invested enough resources in the origin of life question, we cannot yet form an idea of how much time might be saved, nor of how much effort it is to change this time. If the effort is as simple as sending a small probe there with some cells that would be self-sufficient on the planet, and then dropping them into the ocean at some propitious spot, perhaps they would do it to speed up evolution even by a small amount.

For the purpose of discussing this type of planet more easily, let’s call any planet which will, with high probability, develop life and intelligent life on its own, if left unaided, a solo planet. This definition is broad, and is not exactly what some of the colonizers are looking for. Recall that category 0 and category 1a colonizers, those with the Columbus and the heritage memes, are interested in replicating their own ecology, that of their home planet, on their colonies. Category 1b on the other hand, with the warden meme, is interested in promoting life throughout the galaxy. Civilizations in the category 1b would look upon any solo planet and probably let it alone. Civiliztions in category 0 will eliminate any ecology that does not match theirs, unless it is a well-defended planet. Category 1a home planets will make the decision economically. They are interested in multiplying their home world through the galaxy, and if it is easier to find a sweet spot world elsewhere, without life or with a very early stage of life that is easily supplanted by their own, it is better that trying to eradicate life on a solo planet in a later stage of evolution.

This raises two more detailed questions. One is the question raised before: is there only one form of life that can evolve intelligent life-forms? If so, there would be no question of eradication. If it has life, it has life like the home world’s. The decisions that colonizers make are somewhat simpler. They have a speed-up question to ask, and that is all. They do not disturb what will happen as there is only one pathway to intelligent life, and a solo world, by definition, will develop it, barring some catastrophe. The colonizers might do something about potential catastrophes, but not to change the order of evolution that is already occurring on the solo planet.

The second question needs only be asked if the answer to the first one is no. If it is true that other forms of life can occur, that there are two of them at least, then the colonizers' decisions are more complex, and the categories split apart on some possible habitable worlds. When we say forms of life, we do not mean that butterflies have different colors on the new world, or that there are fish with different gill patterns, or any one of the more or less random details of particular species or genus’s are different. What constitutes a different life-form would be something drastic, such as the use of a chemical other than DNA for coding of control of cellular development, or the use of different amino acids for the four bases of the coding, or the coding scheme being with six bases per gene, instead of four. Alternatively, it might be using DNA as we know it, but life being solely chemotrophs, who somehow develop intelligence. It is not that the colonizers will eventually see the same large land animals as on their home planet, but that they may never see animals at all, only sea creatures.

Now it gets interesting. If there are different pathways to intelligent life, meaning different types of intelligent creatures, tool-using ones that can create a civilization and try for the stars, what causes the difference? Is it random chance, that during the time of the first batch of Great Filters, the unlikely event that occurred was of the fourth type, which led to chemotrophs, rather than the first type, which led to primates? If it is not random chance, was it some condition on the planet, either permanently or at some time in the evolutionary cycle? Was it the star type, being the luminosity and the metallicity? Here the higher or lower energy photons might have an effect, such as on the development of chlorophyll or a surrogate for photosynthesis? Was it the edge of the habitable zone that the planet was on, with near-boiling waters leading to a different form of more stable coding language, and cold waters leading to our kind? What it the amount of gravity on the planet, which affects what is in the atmosphere and also how hard the ocean to land transition might be? Was it the exposure of certain minerals under the sea, leading to the possibility of incorporating them in natural chemosynthesis? The list could certainly be expanded.

If there is a strong correlation between physical characteristics of the star and the planet with the type of life that develops, this colors the choices that a colonizer would have to make. A colonizer coming from a low-gravity planet around an M star might simply give up on a higher gravity planet around a G8 star. Their forms of life would simply not work. If this correlation is the case, category 0 and category 1a colonizers would be forced to form layers of colonies. Two completely separate life-forms might form and colonize the galaxy, but one only does their sweet spot planets, which are G8/high gravity planets, and the other does their sweet spot planets, which are M/low gravity planets. They might even talk to each other but not interfere with the other life-form’s activities in the least. It is like they are in two different galaxies, as far as colonization would go.

This means a lot for observables here on Earth. Communication might be happening between planets of each of the home worlds, but the communications would be of longer range, as the habitable planets are fewer and farther between. They would likely also be on different channels, meaning frequency band and encoding, although with completely separate agendas, it is conceivable they could form a pact to cut down on the number of channels. It looks like a lot of excitement for Earthlings in the next century or so when we develop the right listening apparatus.

Tuesday, July 28, 2015

Alien Civilization Categories and Their Memes

In trying to understand what are the constants of alien civilizations that have star traveling potential, we try to understand the basic constraints under which they must live, such as the need for recycling and efficiency, if they are going to survive for millennia. Another way to understand them is to try and think through what are the basic categories in which they might fall. One of those categories is their attitude toward star-traveling. We have divided the spectrum of alien civilizations into five categories, ranging from 0, voracious colonizers, to 4, spiritless has-beens.

Memes are the beliefs that the civilization has, which power its decision-making, and which are preserved as they are taught to children as the foundation of the culture. The memes for an alien civilization of category 0 includes the definition of themselves as champions of technology. The origin of such beliefs is not hard to see. They have risen from their equivalent of our cavemen to possessing all the theoretical knowledge of science and engineering, and are virtually omniscient in the appropriate sense of the word. All civilizations which keep pushing on their technology do this, but a category 0 civilization takes this accomplishment as the hallmark of their culture. They see themselves as engineers, and seek to propagate their abilities everywhere. They certainly have many other components to their credos, their set of memes, but this is the one that is emphasized.

As an alien civilization moves ever upward in technological capability, toward asymptotic technology, its memes may shift. Early on, there may have been competing ones, but the set hardens, becomes universal in extent, and possibly thins out to components that are appropriate for a highly advanced alien civilization. By the time the alien civilization gets to star travel, having overcome scientific questions that interfere with it, the memes would also have been crystallized. For simplicity, we might refer to the meme that drives a category 0 civilization as the Columbus meme. Columbus took off on an epic voyage, and was supported by those who were, initially or later, believers in colonization no matter what.

Category 1 is a bit of a problem. There are two sources of it. The difference is exactly what they are trying to do with their colonies. Let’s call one subcategory 1a. These are the alien civilizations that believe in their own excellence, and want to see more of it. They are looking for sweet spot worlds to re-create the excellent home planet that they already created. They feel they did a great job and want to continue to do so. They are driven by the heritage they see behind them, of which they are justifiably proud as a culture. This pride says to them that their history is not over, it is just beginning, now that they have mastered space travel. For simplicity, we might refer to their meme as the heritage meme. They want some more places to establish their heritage.

The other category, 1b, consists of alien civilizations that see themselves as excellent as well, and are interested in other planets to create home worlds on, but not necessarily for themselves. They see their role as the overseers of history. They look back on their home world, and with joy appreciate how beautiful it is, how diverse, how interesting, and principally, how well cared for it is. They see themselves as the farmers who developed agriculture and love their farm. They see themselves as the park wardens who have the responsibility of taking care of the life in the park. They see themselves as guardians of their planet, taking care of the ecology, and reveling in the complexity of life on their world and how it continues to evolve and change. They want to do it again. They differ from category 1a, in that category 1a wants to expand their culture, and category 1b wants to expand life. This difference may seem subtle, but it has implications as to what they do when they colonize. For simplicity, let’s use the term warden meme to refer to what drives them.

Category 2 has no such problems with multiple definitions. They simply want to survive. They are proud of their civilization as well, think it should continue, and will make sacrifices in their own individual lives when called upon to preserve their civilization. But they do not feel a primacy that drives them to colonize and expand. They do not see themselves as a civilization which wants to displace others, or even replicate itself to multiple locations. They are self-satisfied, enjoy the happy lives they lead, and appreciate that it may take a major effort to preserve that for future generations of citizens. They would not go out quietly if faced with another civilization seeking to displace them, but would see that just as they would see any other catastrophe or peril facing them. It is almost like they are walking a thin line between wanting to expand and being willing to disappear. A meme has the ability to create such a fine line, and deserves a simple label as well: the homebody meme. They like their home and are willing to do whatever it takes to preserve one for themselves.

Interstellar nomads, those civilizations forced off their own worlds, but with nowhere to go in a crowded galaxy, are the least fortunate members of category 2. They are homebodies in a travel trailer, making the best of their life, without imposing on any other civilization for too long. Without one or many early colonizers, this category would be empty.

A civilization in category 3 is similar to the homebodies, but without the resourcefulness needed to do something about a peril facing them. They have all the technology of the other categories, but do not use it for space traveling. Perhaps their memes are so tightly connected with their home world that they cannot imagine living elsewhere. Perhaps their memes became eroded during the final stage of their ascent to asymptotic technology that they simply are proud of their technology, but don’t actually want to do anything spectacular with it, like emigrate. An appropriate name for their meme might be the party meme. Their civilization is at a party provided by the abundant resources of their home planet or solar system, and when the party is over, it’s over. Acceptance of fate is another way to describe them, they are simply fatalistic and when something happens, it’s simply part of their segment of history to accept it. They were lucky initially to have arisen in such a place, and like all luck, it ran out. Their game is over.

Down in category 4, the civilization is not proud of itself, and instead individuals are proud of themselves. When they discuss the future, it is short-term, connected with their lives, not of the life of their civilization. Their history is not a heritage for them, but a context in which to live individual lives, and if those lives do not involve taking actions to preserve the civilization, then they don’t. Civilization gradually wanes and disappears. Perhaps there is some resurgence, but if the memes have taken hold and do what memes do, the population simply shrinks, while still enjoying itself. We might call this meme the individual meme. It would not be appropriate to call it the despair meme, as the members of the civilization do not despair about their civilization, they simply do not think of it as an entity or if they do think of it, as an entity worth preserving. All the triumphs of technology are simply part of the context of their lives, not something to inspire them to use it to explore the galaxy, or even to continue to exist as a group. Nobody is committing suicide, they are committing extinction.

Perhaps elaborating on the five or six different categories that we might find alien civilizations in assists in understanding some details of what steps they would take and what evidence they would display, or in the case of category 4, leave behind, which we might somehow and someday detect. Thinking about them clearly, along with possible Great Filters of the various batches already listed, may get us further forward in figuring out where all those pesky aliens are.

Monday, July 27, 2015

Interstellar Communication – Microwave

Earthlings continue to push their technological capabilities for space communication. The Voyager I probe, now Earth’s farthest object, is about 130 AU out, or better, 36 light hours from Earth. It broadcasts back to Earth every six months, using the power from its radioisotope generator, which has about 250 watts at this time. It has a 3.7 m antenna and broadcasts at X-band. This is picked up by earthbound antennas, ranging up to 70 m in diameter.

For fun, let’s extrapolate this to 10 light years, or about 2500 times as far. Since received power drops by distance squared, somehow the system has to be upgraded a factor of about 6 million. For starters, assume there is a good reactor powering it, not just a plutonium RTG. Give it 1 million watts, which is a factor of 4000 already. Now we need a factor of 1500. Assume the antenna is 10 times the size, and since beamwidth goes as the square of the ratio of the frequency and the aperture, this is an improvement of 100. Now we need a factor of 15.

The existing receiving antenna is 70 m, but let’s assume we build a big, big antenna in space, 700 m in diameter. That’s another factor of 100 and we only needed 15. We now have built an interstellar communications channel. The Voyager I doesn’t talk frequently, or with a high baud rate, but the super-sized system we speculate about here could do plenty more that just get some minimal data back to Earth.

It would be possible to go into some interesting engineering calculations on how big a package this all would be, and how much propulsion power it would take to get it up to some nice fast interstellar speed like 10% of light speed. A lot would be needed, of course, but instead let’s talk about what it means for alien civilizations. Any alien civilization that has been around for millennia and has progressed to asymptotic technology would look at this design and see many ways to do it better, simpler, with lower weight, and so on. That is not the point. The point is that the galaxy can be wired for communications.

If an alien civilization sets up a colony 10 light years away, it can be in contact with it, given the 10 year time lag in receiving a message. Obviously a larger system could transmit more bandwidth. The point is that it is possible. Not only can an alien civilization set up colonies, it can set up a communications network so that information can be passed on it. An order for a thousand tons of silicon can be sent back. A report on the failure of a landing probe can be transmitted. Health status on the re-awakened crew can go home.

Recall that since alien society would have long passed into a stable state, we noted that traveling for aliens over long periods would not be the same as Earthlings would experience, in that when we got home from a hundred year journey, the whole face of the planet might be different. When aliens returned at year 174433, it looks pretty much like it did at year 174333 when they left. It is the same for communications. Ten years to get the message out and ten years to get the message back? No problem, the same master computer will get the message as sent it, the right citizens, robots or intellos will hear it and do what needs to be done, even if they are not the ones connected to the launch. This is abbreviated by saying that aliens in an aeons-old civilization are fungible. They are all able to do what is necessary, and who does it is likely unimportant.

In the previous post on interstellar communications, it was noted that there are two big reasons for using it. One was connected with colonization, and the possibility of communications means that a one-way trip is sufficient. Nobody needs to return home with the video. However, communication means a big reactor has to be loaded onto the probe, but surprisingly enough, a 1 megawatt reactor can be made compact, and shadow shielding used so the weight of all that lead around the reactor will not be needed. Shadow shielding means the payload is shielded by a wall, and that’s all. The rest of the neutrons can go spraying out to space with no worries at all. This is under the assumption that small fusion reactors are a no-go, but Earth has no clue about this at this time. If they are possible, a lighter weight probe may be possible.

A big antenna is also needed, but unless the probe is going to go flying through a dense cloud of interstellar gas, not much strength is needed. These clouds can be avoided in most cases.

There is still a question of deceleration in the destination solar system, in case the originating home planet wants to get a longer look at the planets there, perhaps do some close-ups. Time is not of the essence in a civilization whose age might be very many millennia. It might not be millions of years old, as it is important, if an alien civilization is going to do colonization, to get there before anyone else does, but that still leaves a very long time, except in some vanishingly small probability cases. Deceleration will raise the mass, but the reactor can be designed to have power for a long time, and running around the solar system at a slow speed, comparable with orbital speeds not light speeds, can be done to explore wherever the originating planet decides. It is very unlikely that the originating planet will have to decide anything, however, as by the time the probe is launched, artificial intelligence will certainly be able to make these decisions locally, using general guidelines set up by the launch team. One way communications will be what is important.

The second big reason is deterrence and surveillance. In the situation where an alien civilization sees itself on the colonization path of another alien civilization, one that has been around longer and has developed a sphere of colony worlds, having some surveillance that one of the colonies on the closest part of the outer envelope is not going to be sending something nasty their way would be a good thing. Having the ability to deter any such ventures with their own weapons, connected with a reliable communication channel, would be another good thing. Whether such deterrence is possible remains to be explored, but the communications part of it is not a show-stopper. There may be others, like the need to operate covertly, but that will require a bit more thought to get even the first glimpse of the options involved.

So, now that we know ET can call home, as long as he has a megawatt reactor in orbit, it is time to think about whether we can intercept any of these communications. Beamwidths on the supersized system are about a degree, so there are photons spewing all over the place near the beamline of one of these systems. However, IR or visible light may be a better choice; we need to discuss these options as well. Aliens may be using any part of the electromagnetic spectrum as far as we know, and it would be interesting to try and get a clue as to which part they might prefer.

Sunday, July 26, 2015

Category Zero Alien Civilizations

In a previous post, a fourth category of alien civilizations was discussed. This was the extreme case of a civilization that simply did not want to continue, not because of scarcity or catastrophe, but because of a universal belief, a meme, that devalued their civilization, so that its continuation was not a priority for the individuals. And this vision, or rather lack of one, would eventually lead to an extinction of the species that formed the civilization. On their planet, life would go on, and perhaps another intelligent species would evolve, sooner or later, but theirs comes to an end.

The spectrum of four categories spreads across one of the variables that drives the answer to the questions this blog is discussing, such as ‘Where are the aliens?’ and ‘What can we deduce about alien civilizations?’ The spectrum ranges across the desire of aliens to do star-traveling for any reason, and thinking about alien civilization has led to the indication that colonization would be almost the only justification for star-traveling that would justify the expense. The colonization variable for this spectrum ranges from category 1, which wants to colonize a lot, through category 2, which only wants to colonize if they are forced to by a catastrophe affecting their home solar system or their only world, through category 3, which doesn’t even respond to a catastrophe by emigrating but dies in place, and then to category 4, which doesn’t even want to continue colonizing, or living in, their own home world.

Despite the poor choice of numbering system for these categories, there is one on the other end of the spectrum, which we are forced to call category 0. These are possible civilizations which not only want to colonize other planets, but they want to keep other civilizations from colonizing planets in the galaxy, and in the extreme, would prefer other civilizations to expire, and may even help them do so. These are civilizations that believe in colonizing the galaxy and beyond if they can, and have no reverence for other life at all, but see it as just another factor that may render a habitable planet they find more difficult to colonize. Since interstellar trade makes no economic sense, given the distances, costs, and time to travel from one star to another, there is nothing to do with a planet with other intelligent life for a category 0 civilization but to supplant it. For a category 0 alien civilization, other intelligent life is a mistake that evolution made, and the error needs to be corrected. A category 1 civilization is looking for their own sweet spot worlds to plop down colonies in, and may simply bypass anything that makes the world less desirable. Existing life may be a grave difficulty for homesteading another planet, especially if the genetic coding is different, and it would be costly and difficult to remove or to compete with. Note that the existence of invasive plants and animals is pervasive here on Earth, but these invasive organisms have the same DNA, can eat the same things or can live in the same soil, and do not suffer the difficulties that an alien organism might have in competing with an entire home-grown ecology.

By the way, if the galaxy had one or more early category 1 civilizations, and didn’t get to Earth before we had developed our own life all over the surface and the oceans, this might be a reason why we have been bypassed. There is a ‘Too Hard’ sign on our solar system.

A category 0 civilization sees the existence of alien (to them) life as a great, interesting challenge. They think like this:
Here is a fine world, unfortunately occupied with native plants, animals, and perhaps some primitive civilization or even one getting close to the asymptotic technology limit point, and let’s take it over. Can we figure out how to do this? YES! Can we be successful? YES! Can we clean up this planet and make it a new home for our citizens? YES!

They would have the same attitude toward penumbra planets. Here is a challenge, a world with high winds, but everything else fine. Can we figure out how to get down to the planet with the winds? Can we build structures that will stand up to the winds? Can we still mine and construct a city and build power stations and launch starships? The galaxy is an engineering challenge for a civilization with this type of meme. In and of itself, the meme seems innocuous: We are problem solvers and colonizers. Nothing stops us. But alien (to them) civilizations see the other side of the meme, that of the problem. The problem is eliminated by civilizations of category 0.

This type of alien civilization would not necessarily adopt the same colonization grand strategy as a category 1 alien civilization. Category 1 probably finds the best way to colonize is to locate sweet spot worlds, which may be distant, and then establish colonies there before working to colonize less attractive and less suitable worlds. Category 0 civilizations see the nearest planets which can possibly be colonized as an immediate target, a challenge, an opportunity. They are operating in a way which is efficient in use of resources, keeps costs down, but the benefits are calculated differently. Overcoming problems is the benefit that category 1 does not see. Proving themselves to themselves is the benefit that category 0 sees. Remember that the benefit part of a cost-benefit analysis, on a sufficiently great project, comes from the memes of the civilization that is doing it. Different memes, different benefits, different grand strategy.

What would this mean to our observational program, when we expand it to the detection of biosignatures? If alien civilizations did develop billions of years ago, we would see the same thing, with all worlds that are truly habitable, not habitable in the astronomers’ sense of the world, but habitable by colonizers, inhabited. What would we see? Biosignatures and when we get to it, industrial signatures if such things are visible on a planet occupied by a long-term alien civilization. But if it wasn’t billions of years ago that the first alien civilization entered space as a category 1 or 0 civilization, but much more recently, we would see a different pattern of occupied planets. Around a category 1 home world, we would see at far distances newer colonies, and around older colonies, some development of penumbra worlds. Around a category 0 home world we would see a sphere of colonization, with everything that was habitable being colonized with machine-like precision. The two patterns are: Lots of little blips of biosignatures and industrial signatures or one big ball of biosignatures and industrial signatures.

If we see the ball, we would want to carefully figure out how far away the edge is.

Saturday, July 25, 2015

Batches of Great Filters

We have a Great Filter concept when one of two things happens. First, we recognize that a certain event or process is statistically very rare, and it would prevent most solar systems from giving rise to space tourists. Second, we don’t understand how something happens, so we think maybe it might be one of the former type. All the Great Filter concepts are in the latter. There are none in the former. They are all due to ignorance. In a sense, the plethora of Great Filter concepts is a measure of how little we know about a lot of science.

To make things simpler, perhaps we should divide Great Filter concepts into batches, depending on when in the life cycle of the potential space tourists they fall. Note that we do not figure that any Great Filters are absolute roadblocks, as we have the presumptuous notion that someday we are going to graduate and become one. That’s why we call them Filters instead of something more definitive, like unsurmountable barriers or brick walls. The name is pretty catchy, too.

Since we have dispensed with the habitable zone exo-planets recently, we are left with the first batch being the generation of self-replicating molecules. All we need is for one self-replicating molecule to be formed and start self-replicating, and the planet is past this whole batch of Great Filters. Suppose we knew that self-replicating molecules only form in water solutions, and we knew that there were some conditions needed for the formation of the molecule and perhaps some different ones for self-replication to happen. Then we could translate these conditions into what we know about exo-planetary oceanic chemistry and decide if any of them were unlikely to happen on most exo-planets in the habitable zone of some star. What might be found? Having an ocean is one. Since we have defined the habitable zone as a zone in which water is liquid, it looks like we have used a circular definition to eliminate this one. But we haven’t. Where does the water come from? We don’t know where the water on Earth’s surface came from, and so it is hard to extrapolate to an exo-planet. We do know that there is ice on outer planets and moons in our solar system, and we think the comets have lots of it. One concept is that after the Earth formed, some comet with a lot of water bumped into it and deposited the water. If that is true, this phenomenon has Great Filter written all over it. The right kind of comet, the water bearing kind, smacks into the primordial planet and deposits a lot of H2O. The planet doesn’t disassociate the water, doesn’t absorb it into the rocks it is made of, doesn’t lose it through evaporation, and allows it to form some really big puddles. Put his in batch 1 of Great Filters.

Batch 2 of the Great Filters occur between that initial self-replicating molecule getting formed, maybe of carbon but maybe of anything else, mutating and getting large enough to form a chemical complex that is also self-replicating. It is easy to envision how it starts, by having the original molecule form a bond between itself and another self-replicating molecule, of which there may be only one kind or many. It is not so easy to envision the next steps, as the dimer turns into a chemical complex. Probably, one of the collected chemicals is a catalyst for some others, and this goes on and on, until the catalyst is a long string of catalysts, and most of the stuff in the complex gets made, not by self-replication, but by catalysis. So the second batch of Great Filters relates to the transition between a single self-replicating molecule and a chemical complex formed by catalysis mediated by one or a few specialized chemicals.

It is likely that the catalytic molecule is a carbon chain, as long chains with other backbones do not exist, as far as we know. Let the third batch be the enclosure of the chemical complex inside a membrane, also made by catalysis, or perhaps it is one of the few things that is still self-replicating. Now we have a cell, which signals the transition out of the third batch of Great Filters. The fourth batch involves much more mutation of the catalyst complex, and eventually leads to a multi-cellular organism. We are still thinking as if the oceanic hypothesis is correct, but if it is not, and life forms in some surface formation of broken up rock or something else you might find on an early planet, the batches seem to still fit.

Now that we have a multicellular organism, we are back to the ocean hypothesis. These multicellular organisms are chemotrophs, living on some source of chemical energy in the ocean. They are going to stay in the ocean until they develop a better energy source, and it is, of course, chlorophyll. The stages of the modification of the organism form the fifth batch of Great Filters. They have been discussed in another post already.

Once you have chlorophyll in a self-replicating organism, it is no longer necessary for that organism to stay around the source of chemical energy that its predecessors used, but it can go wherever there are photons. Which is everywhere near the surface of the ocean. Supposedly our atmosphere is a waste product of these organisms. When scientists talk about the first biosignatures to be searched for on other planets, they are mostly talking about chlorophyll searches, not for cells or organisms containing chlorophyll, but for their excreta. They are searching for worlds that have made it through the first five batches of Great Filter concepts.

The next step is to colonize some land, and one of the Great Filters in the sixth batch is the existence of land. Land is nice as you don’t have any water to absorb photons before they get to you. It seems ever so simple for a water organism to go to shallow water, and into periodically wet areas, and then into dry areas. There may be no other items in the sixth batch of GF’s, but that may be because we have over-simplified.

Back in the ocean there is another form of chemical energy to be extracted. That is the chemotrophs themselves. Their bodies have embedded chemical energy in them, and if one of them, a bigger than usual one, was filtering water collecting the sulfates or whatever it used for energy, and a small chemotroph drifted into the collection orifice, you have the first sign of predator-prey combinations. Mutations would make searching for and collecting smaller chemotrophs a specialization, and these predators would likely follow the new chlorophyll containing organisms to the surface of the ocean, continuing to dine on them, and then moving this process onto land. Included in this batch is the development of collection and filtering as a feeding mechanism, as if the chemotrophs are still only using sdsorption to gain nutrients from the ocean water, no predator mutation would be possible. The seventh batch of possible Great Filters involves all the mutations that a predator needs, and the eighth batch of Great Filters involves development of the attributes that an omnivore like just discussed would need to get onto land. When it is in the ocean, it can simply swim around filtering the water for chemotrophs or their successors. No swimming is possible once it gets to land, so some appendages need to be evolved. We have animals. Perhaps the only Great Filter that might exist in the eighth batch of concepts is the initial development of swimming appendages, which could evolve to something to propel the initial steps onto land.

What is needed for a simple animal to evolve to a creature on the verge of intelligence? Perhaps it is the development of additional sensors. Chemical sensors work well under water, but not so well on land. Eyes might be needed. Let this batch of possible Great Filters be numbered nine.

Then comes the great step to intelligence. Perhaps a particular type of vegetation is needed for the development of grasping and then tool-using limbs. Perhaps there needs to be a change in climate, to drive adaptation toward intelligence. Perhaps an asteroid impact to wipe out large successful species of competitors. These competitors prevent the pre-intelligent species, which are capable of evolution to intelligence, from becoming numerous. This can be batch ten, and that is all the batches there are prior to those we might find in a civilization.

As noted above, we have made a collection of our ignorance, the lack of knowledge of our history or better the potential history of any alien species that develops a civilization. With a somewhat neat division, perhaps it will be possible to start eliminating some of these, or at least making them more specific.

Friday, July 24, 2015

A Great Filter – Exo-planets – NOT!

Twenty-five years ago, if you were making a list of potential Great Filters that could explain why aliens have not said hello to us yet, you could have started the list with: No planets. Back then, it was a viable concept that most stars did not have planets, and our sun was the lucky one. Remember that Great Filters are things that prevent aliens from either existing, being intelligent enough to build a starship that wouldn’t break down on a trip to Earth, and interested in coming here for one reason or another. The No Planets Great Filter was perhaps the most basic one. Without a planet to get started on, there was no need to say anything further about the construction of starships or the boringness of Earth or the difficulty of big brains evolving or any other topic that amused you.

But over the last quarter century, that concept has dissolved in a puff of smoke. For some reason, humankind had chosen to spend many billions of dollars on exploring space, and one portion of that funding went to telescopes of increasingly clever kinds and ever increasing sizes. We paid a lot to resolve the very first Great Filter, and our funding paid off. We now know there are planets around almost all stars, and many of them get the right amount of thermal flux from their star so that the surface temperature might be in the range of liquid water. This is in the so-called habitable zone, which is a name that astronomers use to confuse laymen. It means a range of distances from each class of star, chosen so that if the albedo of the planet were as assumed, water could exist there.

An ocean at 90 degrees Celsius may not be your idea of a habitable zone, but it’s a start. It would be possible to come up with a much better definition, probably a much narrower habitable zone, but it’s on the To-Do list. Perhaps another post?

The real point of this ephemeral Great Filter is that if funding were made available for other Great Filters, we might see them evaporate as fast as water on the inner edge of the habitable zone. What are the other ones?

We need to know what does the origin of life need. What are the conditions in which it can happen, and what are the times required for the processes to come to fruition. Timing is important, as if the processes are random in character, and take a billion years to happen, seeing a planet with the right conditions doesn’t answer the story. We need to wait the billion years to see if it keeps these conditions. If we assume the first step is self-replicating chemicals, we need to ask what are the conditions for an initial formation of one, and what are the conditions for replication. Does it need a substrate of a given kind? Does it happen only under pressure, as in a deep ocean? Does it happen only with a certain pH? Does it need a narrow range of some component, such as sulfate in the water? What is the source of energy that will form it, as the self-replicating chemical is likely to need some more energetic molecules to power the process itself? There does not seem to be any momentum in the scientific areas that would bring in funding comparable to that which astronomy gets. But why? Knowing about life in the universe will help us mature our own philosophy and may have a calming effect on our society. Why not fund it?

Perhaps the answer is that film is to blame. We have all seen movies about far off planets, or aliens, or exploring space as a dangerous place, or similar things. This has spun up the interest in astronomy to the level it deserves, but there has been no comparable set of videos about the remaining Great Filters, even the next ones in line, the origin of life ones.

It is hard to conceive of some film plot that would make the science of finding self-replicating chemicals as interesting as the discovery of new Earths. What would it have – two hours of some white-coated chemists mixing vat after vat of trial solutions, and putting them in a temperature and pressure controlled environment, where they were destined to sit for a very long time? How do you make a molecule as interesting to movie-goers as an alien who shoots at you with laser somethings and probably wants to eat you? We may have to face the fact that the next Great Filter set is going to be around for a long time.

The line of Great Filter concepts is quite long, and most of them fall in the bin of ‘really uninteresting stuff’. A chemist might be exhilarated to see how a primitive cell wall could form around some other self-replicating chemical, but who else would be? We hardly have enough interest in these areas to list the various steps that have to occur for primitive life to exist, to say nothing of land animals or smart ones. After you get cell walls, you need to have the wall develop various means of allowing useful chemicals to get in, waste ones to get out, and some way to use them inside the cell. It may be that most of the genes in the average creature's genome relate to things on the cellular level, and the visible stuff is only some percentage of it. That means that there are a slew of Great Filter concepts relating to cell development, and we don’t really understand if any of them are the very low probability events that sort out Great Filter concepts into real Great Filters, assuming there is one or more.

In another post, a word was created for a scientific field that advanced alien societies would have, archeogenetics, which is the reverse investigation of genetics, so they could find out the history of the genes of existing life. What we have been discussing is a way to solve that problem from the opposite end, trying to figure out how life started. Maybe this could be called proto-genetics for lack of anything better. At some point, proto-genetics and archeogenetics might meet, and a complete understanding of the genetic basis of evolution would be understood.

There are pre-proto-genetics Great Filter concepts, those which go from pure chemistry to the first self-replicating chemical, then onward to more complex chemicals and eventually a group of chemicals that self-replicate, eventually allowing one to become a coding mechanism. By this time, there may be a membrane around the group of chemicals, which is either connected to them or one of the things that gets replicated. This batch of steps is as likely to contain a Great Filter as the genetics batch.

A different post pointed out that there could be Great Filters after intelligent life formed a civilization, and several posts discussed what some could be. We have not yet pushed science far enough to understand these, or even to envision a set of steps where they could be resolved. The science is simply not yet defined, and chaos reigns.

Perhaps the best thing that could be done to resolve the Great Filter question is to think through the various batches of questions that could lead to Great Filter concepts, and then try to envision how they might be resolved. The exo-planet former Great Filter was resolved by astronomers who could envision how to make the very ingenious measurements, observations and calculations that led to the discovery of thousands of example exoplanets. Vision seems to be the missing key to this puzzle.

Thursday, July 23, 2015

Starship Detection – Nosecone Heating

It would be nice if starships were like a US Space Shuttle entering the atmosphere, glowing bright and hot, and easy to see with infrared scopes. Unfortunately, the galaxy is not made that way.

A starship traveling through the galaxy from an origin star to a destination star will impact the interstellar medium, which is not uniform entirely, but largely composed of tenuous gas, mostly hydrogen atoms, at cool temperatures. The number density of these atoms is low, less than one per cc. Even flying at a tenth of the speed of light, heating is very small, and any heat could easily be dissipated by conduction through the ship’s outer skin and radiation away at low temperatures. The heating effect of this atomic impact would not be detectable.

The galaxy does have much denser regions, composed of molecular hydrogen with a smattering of other elements, and the number densities of these regions range from a hundred to a million atoms per cc. It is very fortunate for us that these clouds of dense gas exist, as they are what forms stars. These clouds are dense enough so that self-gravitation can overcome the diffusion effects, turbulence, shear, and so on, and gradually get more and more dense, leading to a star and a solar system being formed. We live in one of these.

The dense regions are here and there in the galaxy, but mostly in the center of spiral arms. The highest density clouds are what lead to the formation of the hot stars, O, B, and A, and these are what gives off the light in galaxies that we detect. When we look at another spiral galaxy in a telescope, what we see are these hot stars, as they produce the majority of the light, especially in the visible regions. They form the characteristic arms of the spiral. Since they don’t live long, the gas that formed them is still nearby, and therefore can be assumed to be in spiral form as well. The gas we observe here in the Milky Way also has this form, and is one of the reasons we have deduced we live in a spiral galaxy as well. Nobody from Andromeda Galaxy is sending snapshots.

There are other dense gas clouds in the galaxy. Not all stars are formed in the spiral arms, and especially the other stars, below A stars, can be formed outside. This means there are gas clouds elsewhere, and these are detectable, but it is a difficult problem. We see the gas because of the absorption of the light that passes through it, but that only gives us a two-dimensional view of the gas, and figuring out the three-dimensional view involves some clever deductions. These clouds are thought to be free-floating, self-gravitating blobs of dense gas, that may someday become a star, or if there is not enough gravitational force generated by it, to eventually dissipate. Other ones can form, so there is a change with time, but only with time measured in galactic time scales.

When a starship goes through one of the densest of these clouds at a tenth of the speed of light, it will experience heating from the impact of the hydrogen at very high speed on the forward cross-section of the ship. These clouds are of the size of tens of light years, so a starship entering one of the clouds will be there a long time, and will grow hotter. Perhaps a very large ship would be detectable, if there ever was one there.

Why wouldn’t the starship avoid such clouds? The answer is that it would. A more advanced civilization would have determined accurate maps of the gas in the galaxy in which it lived, and would know where are the high-density clouds and would plan to avoid them, if they could. A solar system located in one cannot, so an alien civilization living there can either run at slow speed until they exit the cloud, which could be a very long time, or not go at all. Stars and clouds have a random component to their velocity in the galaxy, so having a star run through a cloud is simply a matter of random chance. These clouds only occupy less than 1% of the galactic volume, are mostly but not all in the plane of the galaxy, and so few alien civilizations would find themselves living in one. The only exceptions might be those on the lower end of G class stars, formed in the very large clouds along the spiral arms. An alien civilization on a planet around one of these stars has the bad luck to find itself on a star with a short lifetime, necessitating emigration sooner or later, and then they notice they are inside a huge gas cloud, making the trip more difficult.

If instead, an alien civilization outside the core of the spiral arms found itself sitting near a small cloud, it could restrict its voyaging to directions that do not intersect the cloud. This should be easily done, unless the galaxy happens to be pretty much occupied, and there is little choice they have. Perhaps a solar system in the middle of a high density gas cloud is a sweet spot world, just perfect for emigration. Then their destination is perforce inside a cloud, and they have to figure out how to build their ship to tolerate it.

Note also that a ship going a tenth of the speed of light does not maneuver well. Once you get the starship going at that speed, turning it enough to avoid a gas cloud, which is huge compared to a solar system, is likely impossible. So knowledge of where they are and planning to avoid them is the key to star-faring.

This means that detection of nosecone heating, or heating of whatever sits on the front end of a starship, is not going to happen. Only in some very unusual cases might it ever happen, and the probability of that happening during even a very long observational time is virtually nil. We will know better and better where the nearest clouds to us are, but monitoring them will likely be a waste of time. It will be necessary to devise some other signature to search for if we want to detect emigrant trains or nearby probes or any other type of vessels that we can deduce alien civilizations might want to produce.

There also does not seem to be any apparent reason why an alien civilization would voluntarily choose to send a starship into a small galactic cloud, either before it condensed to a star, or after the condensation had progressed, to ignition or any other time. After ignition, the star’s output, unless it were very cool and weak, would serve to expel the gas from the area. Once a small gas cloud has served its purpose of forming a star, it is of no further use and might as well dissipate.

Category Four Aliens

We have in a previous post talked about category 1 alien civilizations, who have as their mission colonizing the galaxy and beyond, and about category 2 alien civilizations, who have as their mission survival when catastrophe is looming for their solar system, and category 3 alien civilizations, who simply allow such a catastrophe to happen, and go out quietly. There is something more extreme on both ends, and this post is about category four civilizations, who lose their desire to continue existing, long before any catastrophe is happening. They simply don’t want to make the effort to continue their civilization.

This is a potential answer to the question of where all the aliens are. Even now, before we develop the instrumental technology to detect biosignatures, or industrial signatures on exo-planets, we can ask if we are likely to find any. Did they all expire from boredom?

An alien civilization is connected with the species that evolved intelligence and started becoming civilized. It may be that the aliens on some planets scientifically modify their own species in some way, so it has improved attributes, but after all that is done, there is still one species that is connected with the civilization. If it dies out, it is not like the dying out of all the species that have become extinct here on Earth. Here, changes in habitat, the emergence of predators or pests, loss of feedstock, change in climate, or other alterations can pressure a species by more than it can adapt to without some evolutionary change, and it becomes a new species or expires trying. An alien civilization which had sufficiently advanced is beyond all these causes of extinction.

There could also be sudden extinction events, such as when an asteroid impacts the planet. This is a probabilistic event, possibly preventable by advanced societies, and is not what the blog is discussing. The alien civilization simply decides to become extinct. Nothing external made it do so.

The voluntary extinction of an entire civilization is not the same as the suicide of an individual, but there are some commonalities. There is much discussion here on Earth about whether voluntary euthanasia should be permitted, and under what conditions. This relates to a situation where an individual is in untreatable pain, or is approaching death by a cause that is inevitable and unpleasant, and the individual wishes to depart life in a way of his own choosing. Other individuals choose death because of emotional pressure, such as guilt. More do so because of some impending situation, like bankruptcy, that they do not want to live through. Even more have mental problems in which they are not able to clearly evaluate consequences. Besides these four causes, there are certainly more. Every individual is unique.

There is no collective brain in an alien society that could experience any of these four causes and make the decision for the civilization that it is going to disappear. There certainly might be a master computer or network that controls the infrastructure of the civilization, but it is certainly not going to be given the option of extinction. There may be a minefield along the way to asymptotic technology that involves a deranged master computer misusing its control power and causing extensive damage to the infrastructure, but this is nothing related to the extinction decision we are discussing. This is simply a serious delay in the advance of the civilization to the heights it is capable of reaching. Other minefields are the same – no conscious choice to become extinct.

There could be a type of accumulated feeling, extending across the members of the civilization, that the civilization itself is not worth preserving. For lack of a better term, let’s call it malaise. So, if it is common for an alien civilization to transition into category 4 at some point in its trajectory forward , it can be said that there is a Great Filter of Malaise. Malaise is an umbrella term, meaning any feeling of despair or despondency in an individual. We are not talking about a civilization where everybody walks around feeling bad, but about a civilization where they don’t think much of themselves as a whole, despite how great they may feel about themselves individually. Maybe everybody’s happy, but when asked about continuing the civilization for more generations, the answer is ‘Why bother?’

The response, “Why bother”, is manifested by the civilization allowing their population to decline by letting the birth-death ratio fall below one and stay there. If the science of gestation has made sufficient progress when this transition happens, society in general, specifically whoever decides how many births to have, decides to have fewer. If the transition is before the advent of the science of gestation, it will be a summation of individual decisions by whatever gender has offspring, if there is more than one gender on that planet. Less eggs are laid, less embryos started, less buds sprouted, or some other reproduction method goes into decline.

What could cause this? Perhaps Malaise is just another name for the Happy Life Great Filter in an extreme form. The Happy Life Great Filter is normally when a society is doing well, everyone is having a good time, and they don’t want to disrupt this and use the resources to build a starship. They don’t see the point of traveling to other stars. They are focused on their earned enjoyment of the home planet they have, or the solar system they live in if they have gotten that far. Their accumulation of infrastructure capital and the careful management of this infrastructure allows them to spend their time on other activities. This means they transition out of category 1 to category 2.

What would happen if a civilization stopped at the Happy Life Great Filter was faced with an impending catastrophe, that was unavoidable, such as exhaustion of the solar system's economically extractable resources, or a hot sun evolving too far, or a nearby huge star nearing the end of its fuel and planning to go supernova? If they remained in category 2, they would emigrate, and if they mastered how to transport citizens in starships, only a few could go. If they did not want to have any remaining members to experience some sad events, like deprivation or failure of environmental controls, and the prediction time was generations long, they could simply use the birth death ratio to reduce their population so no one was left home to turn out the lights. This would look, in terms of population numbers, very similar to what a category 4 population curve might look like, except the category 4 did it without any looming catastrophe. A category 3 curve might look the same, as the civilizations in this category use such a looming catastrophe as a signal that it was time to close the curtain on their civilization.

Let’s try not to confuse the reaction of a category 3 civilization facing scarcity problems with a category 4 civilization’s choices. A category 4 civilization has plenty of resources left, they just don’t want to stay around and use them.

To be complete, a civilization stuck at the Happy Life Great Filter may adjust its population so the sustainable level of resources was divided among fewer citizens, and each might engage in more expensive activities, but this is a separate issue, an economic issue, rather than one of simply societal fatigue.

If this happened during the climb to asymptotic technology, it could be that their science of societal management has not been developed enough, and it was one of the late starters among the fields of science. Perhaps their training and educational system would go awry, and new citizens would be taught their civilization had no value. If this stuck, they would be in category 4. Or their problem could be a null in their training, so nothing was said about the value of the civilization, and something goes wrong with the updating of education system, which affects adults, that fills in this missing item in their early education, and it fills it in with malaise. In short, the population has a set of beliefs that preserve it, starting with the memes that are on the top, but also including many other ancillary attitudes and impressions, and if somehow the population gets these upside down, from some flaw in their training or educational systems, it becomes a category 4.

The only other way that a civilization could transition from its early evolutionary character into a category 4 one, or transition down from some other category into a 4, is if the population in general did not have any influence on the birth death ratio, but it was controlled externally, by a master computer or network, or by some small subset of individuals, who again were victims of the flaw in programming or education, respectively, and that network or subset made the decision to maintain the birth death ratio at less than one continuously. Perhaps there is yet another source of this transition, and it is a result of the Great Filter of Idiocracy, and the population loses the ability to comprehend their future.

All in all, there are some pathways by which a civilization could become a category 4 before they reach asymptotic technology, where such problems would have been solved. If this is indeed the case for most civilizations, the galaxy will be vacant when we start looking.

Wednesday, July 22, 2015

Aliens from Hot Stars

Let’s talk about star types to set the context for this discussion. Stars are categorized in many ways, but the two which make the most difference to aliens living around one are the mass and the spectral type. Mass is self-explanatory, but the spectral type is determined by the composition of the star. Most stars which are not already burned down to white dwarfs or some other end state are on the main sequence, meaning stars with about the average spectral content. Note that the elemental distribution in a star, where elements are being transmuted on a daily basis, is not like the elemental distribution on a planet. Here on Earth, there is just a very tiny amount of gas escaping and only a very tiny amount of mass accretion via meteors, so the elemental distribution of the planet is fixed in time. Some uranium is decaying, so there is intrinsic change, but it’s not much as uranium is rare and has a long lifetime. Stars are different and change their composition as they burn.

The bottom line is that stars pretty much burn according to an understood process, and the mass and spectral type are correlated closely, closely enough so that spectral type is indicative of mass. And mass is indicative of lifetime. So we can say, ball-park-wise, an O star’s lifetime is in the millions of years, a B star’s is tens of millions of years, an A star’s is around a hundred million years, and an F star’s is about a billion or two or three. Down here where we are, on a G star, lifetimes are around ten billion years and on a K star, something like thirty billion. The longest lived are red dwarfs, M’s, coming it at hundreds of billions or more.

There is a continuous distribution, and the discrete nomenclature is just an indicator. So there are stars, near the boundary of F and G stars, with four billion years, or six billion. The distribution is smooth, with there being much fewer at the upper end and much more at the lower end. Brightness is also strongly correlated with spectral class, with the upper ones much more visible. Most of the stars we see in the night sky are at the upper end of the spectrum, O’s and B’s and A’s.

Nobody lives there. These bright stars have such short lifetimes that a planet in the habitable zone would not have the necessary time to evolve intelligent life. The time it takes rubble around a newly formed star to condense might be about three hundred million years, and then there is some time for the tectonics to stabilize, another hundred million or two. Stellar death has already happened before the planet is stable. F stars are the highest in the spectral classification of stars to have planets. There is no point to looking for them higher up. It is true that everything happens in a distribution, so somewhere there might be a planet or two that formed quite quickly around a hotter star, and so it would be fun to find one, but besides the accolades, it would not be of much use for alien hunting. Maybe a rogue planet could be captured, even more fun to detect and examine, but it wouldn’t have aliens.

If the Earth is a good guide, it takes four billion years or so to form intelligent life, assuming we are it. This means that F stars may have planets, but before they get through the evolutionary cycle, the star burns up and it’s game over. Again, there is a distribution, so maybe around an F star that’s just barely an F, with a lifetime of four billion years, there is a planet which just barely develops life and intelligent life to boot, all just in time to watch the sun turn into a red giant and envelop them.

Stars don’t just turn on like electric lights and stay at a constant temperature. They evolve, and higher stars evolve much faster. This means the habitable zone moves around. Planets have their angular momentum and just keep orbiting the star at about the same radius, while the sun evolves and moves the habitable zone. What was habitable is no longer habitable and what wasn’t habitable might have become so. Either way, that is no place to find an alien world. G stars are the ticket to fame and fortune.

K stars certainly have enough lifetime to generate life, and if they can get past the chlorophyll Great Filter, and maybe other filters, intelligent life. Red dwarfs, probably not. So G stars and K stars are where we look for alien civilizations. Fortunately, there are many of them, over 10% together. The celebrity stars, O’s and B’s and A’s are less than 1% of the total, but their visibility makes up for their numbers, and they are what we navigate by.

The main sequence classification is divided further, using a single digit after the letter to denote the finer divisions, with the 0 meaning hotter. The sun is a G2 star with about 10 billion years of lifetime, of which almost half are gone. This means we have something less than five billion years to figure out alien civilizations, as the tail end of that sequence is where the sun will be evolving the most and messing up our environment.

The upper end of the potential solar systems with alien civilizations is near the F8 or F9 level, where they have just enough time to evolve intelligent life. Aliens on a planet in this situation face unique problems. They will soon realize that their sun is evolving too fast for them to stay on the planet. They can adapt as much as possible, choosing where to live on the planet, but other choices will need to be made. One thing about solar systems may help them. There is no reason to think that hotter stars, being more massive, will not have more mass in their solar system, meaning perhaps more planets. There may be a chance they can migrate to another planet within the same solar system. This will not buy much time on a stellar lifetime scale, but lots on an alien civilization timescale. Their other option for survival is to migrate to another star.

F stars with a lifetime of three or so billion years cannot have been formed when the galaxy was formed, it is too old, thirteen billion years or so. They are formed continuously, many in the densest part of the spiral waves that form the galaxy. This means that if colonization is possible, it will have been done. If there were no category 1 civilizations, just category 2, each existing civilization would be occupying only one planet. If there is a Great Filter operating that keeps all habitable planets from having life already, up to intelligent life given enough time, there will be a place for them to go, and they can devote all their talents and resources to getting there. If there was a category 1 civilization that started a billion years before them, it would have finished the galaxy off, and the F8 guys would have no vacant planets to go to. There are other options, becoming a nomadic civilization for example, or being brutal and taking over some other planet with life already there, perhaps battling some other civilization, likely a category 1, for it. War is expensive and resources are short, so this is a last resort. Overcoming the defenses of a colonized planet with only the resources than can be transported on interstellar ships is quite a formidable problem.

Asymptotic Economics

If we want to have a good idea as to how to detect alien home worlds, or see alien starships, there are many good questions to ask. Questions might be: How much thermal radiation would either emit; what kind of industrial products would be in the atmosphere; or will there be a light signature? These are what might be called direct observational questions. One of the ideas that this blog is predicated on is that we can learn much about the answers to these questions by trying to figure out what an alien civilization would be doing. This requires understanding the life of the alien population, the way they would live, what would determine the actions they take and so on. But perhaps some questions are too far afield.

Economics might seem to be one of the farthest afield. Economics is all about capital and labor, trade, currency, production and consumption and so on. What could this have to do with direct observational questions? Plenty.

Before discussing that, let’s realize that economics on an alien planet, with an advanced civilization, is nothing like economics back on Earth. In physics we are lucky as both we and they have the same laws of physics, and we know some of them. Not so in economics.

If an alien civilization lasts for millennia, and it must in order to do substantial amounts of star-faring, it is going to have to be calm and efficient. There is every reason that it would and could be. Knowledge of how to organize society will be a science by some time early on in their history, and it might not be used immediately, but it will be used. To live millennia requires the re-use of resources, and that implies the efficient use of them. Waste, which to them would mean a failure to properly recycle materials, would be abhorred. They have a planet to live on, and maintaining it for hundreds of generations of life means to maintain it in a stable condition, meaning not that nothing ever changes, but that the changes are small and cyclic. Things come back to where they were with minimal losses. It is true that recycling, even in a very careful society with strong social codes for it, will not be 100%, and some supplies will be necessary to maintain the civilization, but these will be minimal.

The value of materials to the society will of course be great, but it will not be determined on the basis of the usage. It would be based on the attrition that occurs during usage and during recycling. Suppose fluorine and gold are both used and in the same quantities, but that gold recycles, according to the scheme by which it is used, at 99.999% and fluorine, only 99.9%. The usage of fluorine is 100 times the usage of gold, and to maintain the same amounts of both of them, 100 times as much fluorine has to be found and brought into the cities as gold. The demand is multiplied by the inverse of the recycling rate. Supply of one may be quite different from the other, depending on original supplies and depletion to date, so we cannot say what the ratio of value between gold and fluorine would be, but that values are determined by factors that we hardly consider here on earth.

The value of labor to society will be quite different in a civilization that has learned artificial intelligence, robotics, synthetic genetics, and massive amounts of calculation, and has in its records engineering plans and designs for everything, completely debugged. Capital will have been substituted for human labor, so a question would be, what do members of the society do with their time? How do they spend their lives? This might affect the predilection for space travel, if it were not already written in the memes of the society.

How fast are they using up the resources on their planet? Do they have an ocean from which any scarce elements can be extracted, or does the costs of this exceed its value? In other words, does building and maintaining an ocean water distillery use up more resources than it will provide? In a long-term society, things are better expressed in rates. Does the consumption of materials to maintain a sea-water distillery exceed the output of whatever few materials need to be extracted? So, at least for this question, economics plays a large role, but engineering economics rather than any other type.

Resource requirements might also induce them to use interplanetary shipping to bring in some scarce resources, ones the planet has few of or has been depleted of. How would the society decide if it wanted to do this? With resources declining, they do not have the usual opportunity that is discussed here on Earth in economics classes, substitution. They have already substituted and are down, after enough millennia, to where substitution is no longer an option. They are all substituted already. They have a choice of emigrating, going extinct, or using interplanetary shipping. This assumes they have some planets in their solar system which are useful for resource extraction. Emigration is a huge cost, and extinction violates their fundamental memes, so they have to do interplanetary shipping.

There are other reasons why they would be forced to migrate, and some of these are stellar death or evolution, galactic perils of many kinds, planetary tectonic upheavals, and perhaps others not envisioned here. If they are forced to migrate on an earlier time scale than resource exhaustion on their home planet, they will not enter a phase of interplanetary shipping by necessity. It may be that interplanetary shipping is less costly than some other way of obtaining certain resources from their own planet, so it would be done anyway.

We don’t have any good estimates of forced migration times, nor of planetary resource exhaustion times, so we cannot compare them. These might be calculated when we have some more decades of science, perhaps by the time we are able to better observe exo-planets in our vicinity. If it turns out that interplanetary shipping is a necessity in most cases, this might be an observable for us. Note that if some material is needed from some moon, let’s hypothesize, it won’t be done in a rate to match its usage, but instead at a much lower rate of its usage divided by the recycling rate. If it is used 200 times on average before it dissipates below a recoverable limit, 1/200 of the usage rate is all that would be required in shipping. Still, there may be enough ships that some signature is detectable.

There are more economics issues that might impact what we will detect, or even if they would come to our solar system. These need to be explored, and include consumption decisions and energy and perhaps more. It looks like another post will be needed.

Tuesday, July 21, 2015

Asymptotic Robotics

This post is a discussion of how robotics might be used in an alien civilization, and how this might impact our possible interaction with them or detection of their existence. Recall that the presupposition is that the alien civilization has lasted a long time, long enough to get past the early days which might be chaotic, and long enough to have learned about all there is about science and engineering. Robotics is one of the fields that we divide science and engineering into, but they may not. It is conceivable that there are such fundamental differences between mobile robots and controller robots, which do some task while remaining in one place, that the field split apart. There may be huge sub-specialties which are focused on the materials used, the energy sources, the motion actuators, the sensors, the computer or computers used to manage it all, and intangible parts as well. There could well be a branch of science and engineering that relates to software controls, which ensure a robot stays within some bounds of behavior, especially mobile ones.

Also recall that what we call soft sciences now, such as economics and political science, have on the alien planet long since been turned into hard sciences, meaning all the fuzziness has been dealt with, and the sciences are quantitative and measurable. The limits on them are the limits on omniscience, as discussed elsewhere. With this knowledge comes social calm, and alien civilizations have this as their theme for the later millennia. One alien civilization may achieve it much faster than another, for various reasons buried in their histories, but if science and engineering are allowed to accumulate, they will reach the pinnacle of asymptotic technology, which includes the knowledge of star-faring. Of course there are obstacles to that, and a society may fall prey to one that eliminates its ability to retain what it has learned, and descend into a dark age. Perhaps it will be temporary, or permanent, as there are traps into which an alien society might fall which don’t allow recovery, such as the establishment of anti-science memes, scarcity problems, genetic drift away from intelligence, and certainly others. These are not the alien civilizations we might meet or detect long before we move to the stars, if we ever do. These halted or collapsed civilizations are certainly interesting, and should be discussed, as if they are present in the galaxy, alien civilizations which do travel the stars may meet them, and interact on some basis. This may influence what we might detect on exo-planets, once our astronomical instruments achieve the next generation or two in capability.

In a different post we discussed asymptotic genetics, and introduced a word for convenience, intello, meaning an intelligent organism grown for some purpose. One basic difference between intellos and mobile robots is that intellos are grown as cellular objects, and robots are assembled from separately constructed parts. If you consider one of each, the intello is much less expensive to produce, provided the DNA or whatever coding has already been done. A robot also has design work that precedes its construction, which might be comparable to the coding for an intello. Both would have been automated to a large degree, and perhaps to simply a level of asking for specifications.

An intello is grown somewhere, as a farm animal might be, except that it requires training more extensively. A robot needs manufacturing facilities, one for each part. Manufacturing might be done by something descended from our latest manufacturing innovation, 3-d printing, in that each part is built up by deposition. But each part is still built individually, and then assembled. For a lot size of one, it would certainly seem that an intello is less expensive to produce.

For a larger lot size, the facilities would be amortized over the whole production quantity. This would reduce the per unit cost of the robots, but not so much the intellos, as their production takes a dedicated facility that lasts first over the duration of gestation, and then over the duration of growth and training. So, on a cost basis, the alien civilization might use intellos for some tasks, where individual specialization was needed, and robots for tasks where there was a large number of identical processes to be done. In an alien civilization, production and recycling tasks have a repetitive nature and are done to meet the needs of the whole population, therefore in mass, so robots would appear here. Facility care, if there were large numbers of unique facilities, might be done by intellos. Anything that required specialization, such as household service, might better have intellos.

The cost of an object is also affected by the cost of disposal, especially where there are no dumps, only recycling. A robot can be repaired, or if too many parts have reached the end of service life, can be disassembled and the parts easily separated for recycling and remanufacturing. However, here we have a large number of specialized facilities for the different classes of parts. An intello just dies, and the body is recycled. This would push the cost factor toward intellos, provided there is a balance in one area: longevity. The cost of something which provides a service for a long time is better expressed as a cost per year of service, rather than overall costs. Other costs are converted to per year costs. If a robot can be built to last a hundred years without going overboard on construction costs and materials, but a intello can live for three hundred, the cost advantage tips its way. Some Earth animals live for two hundred years or more, so the possibility of three hundred or even more is conceivable. Recall that alien society has become stable, meaning that the task breakdown and composition remains constant over any lifetime.

Maintenance and repair costs also might favor intellos. Intellos can be designed like the natural life on the planet, to be self-maintaining and self-repairing. Specialized repair facilities are necessary for robots, although if a large stock of replacement parts are available for the more common robots, maintenance and repair would be simple. All in all, the cost basis might favor intellos more than we might initially guess. Intellos also have self-diagnostic nerves, whereas to build a robot to accurately sense its own status down to the level that a normal nervous system would requires a on-board communication network within the robotic body far beyond what we imagine today.

A cost basis is not the only reason for selecting one or the other; there may be task requirements that eliminate one or the other, or establish a preference. The members of the civilization may prefer to interact with intellos. Thus, even with a small cost disadvantage, they would be used there. Robots have a size advantage, as they can be made larger than biological limits. Large construction jobs might need robotic work, although the construction jobs in a world where recycling is done to a very high degree, are re-construction jobs. Nonetheless, size may matter in this area. Since cells have a finite size, there may be some roles on the other end of the size spectrum as well, as robots can be designed to be quite small.

There are environmental effects as well. There are cells that can withstand radiation much better than others, having a rapid protein and DNA repair capability. Robots can be designed out of radiation-resistant materials. We might expect that isotopic separation has become routine in the alien civilization, and materials built out of isotopes most immune to radiation effects could last far longer than ones we could build today and longer than any biological creature. Thus, work on nuclear energy facilities would likely be done by robotics, not intellos. These facilities might occupy a significant fraction of an alien city’s total space, and provide many tasks.

Robots are also much less sensitive to temperature, and can be designed to be largely unaffected by vacuum or high pressure. Tasks where these are involved will be wholly robotic.

Are there some tasks which have such specialized requirements that one of the two options are excluded? The neural network that grows in advanced organic creatures has a degree of complexity that will press robotic designers to match. If so, tasks which are not specialized but require a high degree of motion control and local and global sensing might be intello-only. Perhaps music playing on traditional instruments is an example. Could a robot be built with enough fingertip sensitivity, along with motion control, to match what an organic being could do?

Space traveling is a unique requirement, and star-faring is even more extreme. It is very obvious that building habitats for organic creatures is quite costly, compared to building and flying robots. Our current baby steps into space have shown this. There seems to be no reason why this would be different for an advanced alien civilization for interplanetary travel. But star travel has one unique difference. It lasts longer. Can robots be built to be as self-repairing as an organic being over the long period that a starship would travel? It is an interesting thought experiment to compare a possible starship, a probe not a colonization ship, controlled by an organic entity, with a longevity greater than that of the travel time, by regenerating cells continuously, with a starship controlled by a robotic entity that has to be able to repair parts of its controller itself periodically. Cellular growth is built into the organic entity, but is an add-on for the robotic one, meaning that there is more checking on status, more reliability questions, and more likelihood of mission failure. As far as we can tell now, it seems certainly possible that any pre-colonization ships would be controlled not programmatically like a robot, but by neural processing, or perhaps by a clever combination of them. This has implications for the size and the thermal signature of any interstellar probe that we might search for inside our solar system.