What Lasts Ten Thousand Years?

You can walk around in monuments two thousand years old in Egypt. Archaeologists dig up mounds with relics from five thousand years ago. If we wanted to know if there was an advanced civilization somewhere on Earth ten or twenty thousand years ago, what might be found that could tell us at least where one of its cities were and even better, tell us a little about it?

If the ancients wanted to just let everybody in the future know they had been here on Earth, they might just make a huge block of tungsten, and set it up somewhere so that any following civilization that could identify metal would know that this was not a natural object, and could not have been made by some set of hunter-gatherers. Finding and refining out a cubic meter or ten of tungsten requires some serious metallurgy.

If we assume that the ancient civilization had some smart people, and for whatever reason, they wanted to leave a mark on the planet that they had been there, they would certainly have tried to think through all the possible events that might happen between the time they build their marker, and the time that another civilization would get to be sufficiently advanced to know what it was they were looking at. They wouldn't have thought of building the marker, or cared about it at all, if they didn't have the premonition, or more than a premonition, that their civilization wasn't going to survive much longer. They would have recognized the threat and deduced it was unavoidable. It is hard to imagine an entire civilization disappearing, and we don't have any clue as to what might do that, just some concepts that are perhaps possible. The ancients would be thinking of how to build a marker which wouldn't be engulfed by whatever was going to do their civilization in, and they also had to think about other possible catastrophes that could occur in the inter-civilization period.

Perhaps thinking of an example would make things clearer. Suppose the ancients were good at astronomy, and had noticed that there was an asteroid, far out in space when first discovered, that was going to make a direct hit on Earth, and it was big enough to annihilate almost everything. They had the telescopes to detect these, and had been detecting them for long enough to predict orbits very exactly. This means they might have been at least a couple of hundred years older, as measured from the advent to telescopic astronomy, that we are now on Earth.

Asteroid strikes have happened many times before to Earth and a prominent theory of why the dinosaurs stopped ruling the Earth and gave way to mammals was that a large asteroid hit the planet, landing in the Yucutan or just offshore, producing such a chaos of heat and dust and shock waves and tsunamis and earthquakes and vulcanism and lots more that dinosaurs couldn't survive. Some tiny mammals figured out how to, and they led to us, after another 66 million years of evolution. The asteroid for our example couldn't be this big, as there would be a geological record, but it couldn't be too small either. If it hit the deep ocean, there might not be any crater to find and no clues like the iridium layer that Alvarez found as a signature of an impact event for the Yucutan strike. An ocean impact would flood all coastal terrain, and create a huge amount of hot water vapor in the atmosphere, which would probably mean rain for a long, extended period, almost everywhere. The temperature would rise and stay up for a long time, as the Earth slowly returned to its pre-impact situation, less most life.

Orbits of asteroids vary in their periods, and some of the larger ones go far beyond the gas giants, and take a hundred years or so to cycle back to the near planets. So the ancients might have one or more centuries to plan how to make their marker, and could think long and deep about its preservation for millennia.

One initial question would be: where to put the marker? It couldn't be anywhere near the coast, or inland as far as the tsumanis would reach. It couldn't be inland anywhere that would be washed away by huge rains, which could flow in existing rivers but also might find other paths to the ocean. It couldn't be anywhere where the crust was thin, as there could be volcanos caused by a rupture in the crust from the impact.

Then there is the problem of ten thousand years of dust falling down on it, perhaps burying it. If it was put on a pedestal, that couldn't be too high and thin, as it might be tipped over. Maybe it should be huge, so the erosion of time would still leave something recognizable. If it was huge, it couldn't be made out of a single metal, like tungsten. Maybe there could be a cap of tungsten at the highest point. Rock easily stays around for ten thousand years, but it can't be too ordinary or the follow-on civilization might think it was from some so-far-unexplained natural phenomena. Before they became sophisticated enough to appreciate what the marker was, they might just think it was another opportunity for quarrying. Then the marker would wind up in parts in places that needed defensive walls, or temples of rock, or anything else extremely solid. Many archeological sites have been victimized by humans, in recent centuries, who had no interest whatsoever in preserving the past but a great interest in finding things that could be sold or used for their own purposes. Incan sites have been especially victimized by those bent on re-use of good materials.

One way to prevent re-use of the marker monument rocks would be to make them too big for a second civilization to use in its earlier period, before they became sophisticated enough to appreciate the preservation of ancient structures. They could also make them into something that could be re-used itself, or added to for re=use, rather than disassembled and carted off. Perhaps they would try to make their monument impressive, with giant statues of solid rock, so that the new civilization would think twice about abusing it. A new civilization might then try to make use of the monument for some purpose, like a temple or a royal palace or something else, and the new monarchs might even claim they had produced it, rather than found it after millennia of being ignored and abandoned. Perhaps a block of tungsten or titanium is the wrong approach, and something that caters to the likely situation in the new civilization's early years would be better. Writing on the monument might be fruitless, as the new civilization will need a long period of development before writing is established and they recognize what those markings are. So, a simple monument, made from large whole rocks that were of the hardest kind that could be used, perhaps with some statues, might be the final choice of the ancient civilization as they faced their doom.

Maybe there might be some remnant of their cities, or vacation spots, or ports or something else which survived the catastrophe and the following millennia, while the few remaining humans went through a return to prehistoric living conditions and gradually re-invented civiization. Sounds like some excellent archaeology needs to be done, and some careful scrutiny to make sure a misclassification does not occur.

Why Now?

Asking the question about whether there could have been a more advanced civilization of humans that was eliminated in a catastrophe, or related questions, leads to some deeper ones. Why did intelligent humans evolve at the time they did? Why didn't we evolve into city-living, culture-appreciating, educated, adept, clever humans two hundred thousand years ago? What delayed our approach? Why weren't we delayed another hundred thousand or two years? Why now?

One way of looking at this is to examine the preconditions for the final leap of evolution, to thinking brains and everything they required, and see when they arose for the first time. The simplistic solution is to just make a list, accurate as possible, of what steps led to humans and see why one of them couldn't have happened earlier.

One detail needed to follow this approach is to decide just where on the taxonomy of animals intelligence could have arisen. The pat answer is that we needed thermally regulating bodies so our brains didn't turn off in the winter. Why is this true? What about evolving in a region with fairly constant temperatures over the year? Perhaps it is a day/night temperature difference that excluded reptiles from becoming intelligent. Suppose some lizard had a complex brain, but could only think during the day when temperatures were warmer; why is this an impossibility? During colder temperatures only the lower brain stem, which is what today's reptiles have, was working. That part would allow the reptile to live like other dumber reptiles, except when temperatures got warmer, and then it could think great thoughts.

If we cannot determine some incontrovertible reason why reptiles couldn't have become more intelligent, the boundary of time when intelligence could have started is pushed back, hundreds of millions of years, when, supposedly, reptile species ruled the entire planet. We should ask: what good would being able to think more complex thoughts do for a reptile? Their ability to survive and reproduce depends on their visual skills, their speed, their ability to recognize hiding places, their ability to capture prey using body and head muscle linkages with eye coordination, and perhaps a few other things. Nowhere in this list is anything that a complex thought might help. Compare that with chimpanzee-like species which could begin to use found objects and then shaped objects as tools. Tool-using elevated species from chimpanzee level to human level. Current eptiles don't have the physiology for that.

So, could we have reptiles of millions of years ago, those who were living in forests, take an evolutionary jump to climbing trees and developing opposing thumbs and dextrous hands? If evolution could do this, why not, over another million years of evolution, could they not develop thermal regulation to some extent? Thermal regulation requires energy, and could reptiles become better hunters or more complete omnivores, and simply follow the pathway to intelligence that proto-chimpanzees would follow millions of years later? Why weren't the steps needed for intelligence, whatever they might have included, completed long ago, in the millions of years scale.

Perhaps evolution couldn't make the total number of jumps needed for this, simultaneously. Was the jungle many millions of years ago more hostile to the growth of intelligence that the forests of a few hundred thousand years ago? What about hands? Some animals climb trees using their claws, which penetrate into the bark or catch on irregularities in the bark of trees, and evolve so that this method improves, as opposed to developing grasping hands, which is a totally different evolutionary path.

Without grasping hands, evolution couldn't take one of its sideways steps. A sideways step in evolution is when a species either mutates its genome by moving one section to another place, perhaps copying it there, which then allows the species access to some new capability, not related to the one for which the genes had evolved for. We can think of the software side of evolution, which is what happens when one generation imparts some wisdom to the next one, which allows the newer generation to use its mental and physical capabilities in a task that it wouldn't have, without the training.

What else in evolutionary pressure serves to force hands to develop? If the species lives on fruits and other pickable objects, hands might be useful here. Alternately, if the animal simply eats leaves and flowers for nourishment, then hands don't play much of a role and wouldn't be selected for in the evolutionary process. Fruit provides more concentrated nourishment that leaves, as do seeds and some roots. Was food selection the problem that kept reptiles from becoming intelligent millions of years ago?

This doesn't sound correct. Why couldn't reptiles evolve to eat fruit and seeds, if primates could? Were there fruits around millions of years ago in the equivalent of forests?

Perhaps the question should be asked in a completely different way. How do we know that some lizard species did not develop intelligence of some sort two hundred million years ago? Would there be anything detectable this many years after they became extinct? Perhaps the intelligent lizards lasted a million years and build cities. What kind of rubble lasts two hundred million years? Do we know how to do excavations to figure out the answer to this question?

One thing we do have is fossils. Fossils occur when some animal does some stupid thing and gets caught in some mud and dies and then the mud turns to stone. Because of some perversity of nature, braincases are not often found in fossils. But recently some have.

To be intelligent, one needs a large brain, measured in terms of brainweight to bodyweight. Some recent finds of reptiles raises the possibility that some of them may have larger brains that has been expected by the earlier-discovered fossils. If we assume that civilized reptiles two hundred million years ago managed to largely avoid getting stuck in mud pits and turned into fossils, then their absence in our dinosaur skeletal displays in the different natural history museums around the world is understandable.

What else might be left behind from a civilizatin of intelligent creatures that lived for a million years and died out two hundred million years ago? What might get buried and refound that would last two hundred million years? For early human civilizations, we look at burial mounds. These are put together in the first few thousand years of civilization, and then everybody stops doing it. Inside these burial mounds there are gold ornaments and jewels, which might be contenders for enduring the forces of nature for millions of years. Would a civilization that lasted much longer not simply collect these things from their own archaic burial mounds and put them in a museum? And since the Earth changes its profile in much shorter times that two hundred million years, moving dirt and rock and lava and water and any materials around on the planetary surface, how could we expect anything from an ancient city to survive. Maybe they invented materials that were more durable than concrete? Concrete might be good for tens of thousands of years, if no earthquake or flood gets to it. What is left after a short time such as a hundred thousand years? Rubble. Maybe there might be some chemical test to see if some rubble we find has some unique features? Rubble near the surface probably wouldn't stay in one place, however.

One thing we can detect for long periods, in very unique situations, is the materials embedded in layers of rock. That is how we suspect a large asteroid hit the planet some 65 million years ago, from the thin layer of iridium-rich deposits all around the world. Would the lizard civilization have put something into their air which would be detectable? It is very hard to think of any possibilities in this area.

The conclusion is beginning to look inescapable. There is no way to tell if we are the first intelligent species to emerge on Earth. All the hubbub that goes on about aliens on other planets coming to visit us might be expanded to ask if there were some 'aliens', of the homegrown variety, right here already. If it could have happened once, maybe it could have happened twice or more times. All of these things would leave no evidence. One result of realizing we might be the tenth intelligent species on Earth rather than the first is that we really don't have a good understanding of evolution yet. Maybe there are clues buried in the genomes of the organisms of Earth that indicate something intelligent was around a very long time before us. It is certainly not clear how this might happen, but we need to grasp at straws to answer this question.

Ancient Civilizations

Common belief here on Earth is that our civilization has been continuously improving since the human species came into existence. It has been a steady sequence of more population, more technology, more areas inhabited, more organization, more culture and so on. With that as our history, it is easy to project onto possible alien civilizations on exoplanets that they too had a uniformly improving history. Then some comparisons can be made, some calculations, and some predictions. That has been the basis of this blog.

What if this is all wrong? What if there have been one or more civilizations on Earth which were wiped out by one or more catastrophes? There are at least two questions that immediately spring up. One is about the evidence that might indicate this is at least possible and not ruled out by everything archeologists, geologists, and other scientists have collected and interpreted. The other is, provided the answer to the first is that the evidence for the simple single rise of civilization is not wholly compelling, what does this mean about potential alien civilizations? If our planet had one or even a series of catastrophes, wiping out mankind down to the hunter-gatherer level, and then mankind built up a following civilization virtually from scratch, maybe this happened on exoplanets as well. 

Why even consider this? There are some scientists and others who see something in the evidence available to us, overlooked to date, which indicates the progression of society has not been wholly linear. They noted that the level of the oldest stonework at a few sites appears to be significantly more capable than later stonework. They raised the possibility that there was a retrogression of technology at least once in the history of humankind. Instead of a fruitless discussion of the arguments involved, just suppose that it is a possibility. We might first ask what kind of catastrophe might destroy civilization but not lead to species extinction, not for humans or for any other noticeable species. Is there even a possible phenomena which could wipe out civilization without ending the human species? 

To be able to completely collapse after such an event, totally but not permanently, means that civilization is much more fragile that has been appreciated before. This fragility needs to be understood in terms of the civilization that existed at the time of the catastrophe. That civilization might have taken some different paths that made it more vulnerable that ours is. Or perhaps we underestimate the fragility of our own civilization. What could wipe out our civilization so that only hunter-gatherer tribes were left? Are there any unique events that could do this? 

There are natural catastrophes, like volcanoes, and human catastrophes, like a biowar which targeted food crops. The list of natural catastrophes is quite well-known, as only a few things could affect mankind world-wide. Ice ages could top the list, as there have been several major ice ages, and many more mini ice ages during the non-ice-age intervals. The causes of ice ages are not conclusively determined, but that is of no consequence to the determination of their effects on a civilization. Perhaps one of the most interesting factors is the albedo of ice. Since it is higher that that of uncovered dirt, vegetation, or ocean water, that means that if something happened to increase the fraction of Earth covered by ice, then the amount of heat received by Earth, in total, would decrease, and it would cool down more. This is a positive feedback loop, and could go either way. Orbital variations might be the trigger for this rapid change. The large gas giants affect the orbit of Earth, as an example, and change its eccentricity, and perhaps other parameters. If we look at the collection of possible Earth orbits over the last billion years, we would see there is a distribution, perhaps a bell curve, of the insolation averaged over each year. If the orbit of the Earth was at one end of the distribution of solar energy intercepted, the end where insolation was largest, the climate could snap from ice age to minimal ice in a short time. At the other end of the distribution, it could snap the other way. 'Snap' might mean less than a thousand years or even less than a few hundred. 

Ice melting on such a vast scale changes the sea level depth by something of the order of a hundred meters. If civilization had adopted mostly coastal cities, they would be wiped out in short order. Perhaps this is one candidate for a civilization-terminating catastrophe. Even a lesser amount of melting might drown most cities. Would this end civilization? 

What would happen to a civilization similar to ours if such an event were to happen? Perhaps over a few centuries, most cities would be inundated. People would have to move to higher ground. There is no question, at least on Earth, that there is bare land available for cities, but the benefits of the locations of the previous, now flooded, cities would not be available. These might be ports. A tremendous amount of our trade is by ocean transport. New ports might be available when the seas stop rising, but during the period of continuous rise: no one would be able to build a port which might be flooded in a few more years. So transportation would be seriously affected. 

The costs of building new cities would be very large, and perhaps enough to overwhelm the economy of Earth, or of any comparable civilization of aliens on an exo-planet with a similar ice age phenomena. Would the economy crash, or just degrade enough so that science and technology would be preserved, and the living standard would only decline a moderate amount, not entirely down to hunter-gatherer level. 

Some of this land would have been agricultural, so some food production would be lost. Many countries would be little affected, and others very seriously affected. Would this mean massive migration? Would it mean wars fought over who would control the remaining good land? On top of the possibility of the economy crashing or at least declining significantly, there is the possibility of war, where the holders of good land attempt to stop huge populations of those from inundated lands entering and taking it over. War might not be local, but in many different places, almost at once. If a faltering economy did not cause enough damage, widescale war on top of it might, and here is a possible scenario for a collapse of civilization. 

There are many other questions related to this issue, but they deserve a separate post.

Detecting Alien Civilizations

Aliens haven't visited us as far as we can tell. They also haven't sent us messages that we could recognize. So, we have to peer out into space and look for them. Finding a planet which has oxygen in its atmosphere is regarded as a signature of life, as oxygen likes to bind to the exposed surface material and wouldn't exist in the atmosphere if it is not being replenished by life processes. At least that's how Earth works, and other planets may use this design as well. But oxygen or not, this says nothing about detecting aliens themselves. If they have an advanced civilization, they may be beaming messages in space, but we haven't been invited to join the network, and don't have a clue as to how to fill out the application. So we need to look for them, and then perhaps we might send a signal that says we want to chat. At least we would know where to send the signal. Detecting alien civilizations on a planet is difficult because they likely would not create any signatures on the planet which would be visible at lightyears distances, unless we built some very large telescopes. Even then, seeing some city on the planet's surface is unlikely. Perhaps if they traveled in space they might be detected. Consider the background of the signatures we could look for. If there was a planet like Earth, with life and even worse, weather and geological features and water features and more, all these would make the detection of life with low-resolution telescopes difficult. By low resolution, we do not mean little things like Palomar, but instead telescopes which have only ten to a hundred pixels resolution across the diameter of the exo-planet. That means, we would be seeing, at the best, only things which could stand out at those resolutions. What might they be? Suppose there was a very large city somewhere on the planet. This might be a few kilometers across, compared to the size of the planet, which might be several thousand. This is not going to be visible unless there is some spectral assistance. For example, if one pole of the planet was very cold, at the time we observed it, and the city was warm, we might see one pixel bright in the far infrared, surrounded by black (in infrared) pixels. This would be a good option, except infrared is absorbed by any atmosphere we might expect on a Earth-like planet. Maybe they have a thin atmosphere, very warm cities, and very cold polar areas, and then we might see the city. There is a much better chance to see some warm city on a satellite without atmosphere. If they had, on one of their planets, a moon with no atmosphere, but plenty of minerals and other things that were useful for the aliens, and they built some surface habitation there, it would be easier to see. The habitation would certainly be smaller, but the moon might be, for at least part of its orbit, much colder and not only that, more uniform in temperature. Thus, the detetability of a far infrared signal might be easier, even if the habitation was smaller than a city on the origin planet. So, an alien civilization with interplanetary capability might be easier to detect. There does not even need to be the assumption that the origin planet is in the same solar system. No matter how they get to the cold, cold satellite, the detectability calculation is the same. If, for example, their origin planet was on one star of a binary system, and the satellite they were visiting and colonizing was on the other, they would be detectable. And it certainly does not have to be a satellite. Any small world with no or a thin atmosphere would be just as good for detection. It might be that the future of alien space travel from this particular planet was very practical. Since there might not be any planet similar to their home planet within many light years, they might have decided they were going to go to many of the solar systems near them, within say ten light years, and set up colonies wherever they could be self-supporting. This could mean some good fraction of the solar systems around them will have some colony there. Perhaps a good fraction of these colonies would be detectable. How many colonies might there be? Suppose the universe is generous, and it is possible to set up a self-sustaining colony on a wide variety of smaller planets. Because we don't have any good knowledge of this number, none at all actually, because no one seems to have worked on it, let's assume it is 10%. So, if the average density of solar systems around their origin planet is about one in every 10 light year cube, the average alien civilization should have a colonizable solar system within about 9 or 10 light years. If their ship travels at 1% of the speed of light, it should take them about 1000 years of travel, plus some preparation time, to move to their first colony. If the universe is even more generous, and a self-sustaining colony can build their own starship in a thousand years from the foundation, they can start their second round of travel at 2000 years and arrive at the next planet at 3000 years. If they do two at a time, this means by 3000 years they have seven planets. In 2N-1 thousand years, they have 2 to the Nth – 1 planets. This works out to a million planets in about forty thousand years and a billion in less than sixty. These numbers are not realistic, but just are shown here to explain that covering the galaxy with alien colonies doesn't take that long. They could go much, much slower if they chose, and use up fifty million years colonizing the galaxy. Or whatever. If we want to go looking for alien civilizations, so that we can contact them or sell them our planet or just wish them well, it seems there is a fundamental division in how we choose to do it. The deciding question is: Is star travel possible, for an advanced alien civilization with a solar system full of resources and plenty of time to do anything necessary? If the answer is yes, it seems rather foolish to concentrate on looking for their home world. We want to know where could they have a self-sustaining colony, because there could be a billion of those and only one home world. Bad, bad odds. If the answer is no, then we might first ask: why are we doing this? Every civilization is all isolated in their home solar system, and what possible use could it be to find some other set of prisoners? Commiseration? But if someone could come up with a non-nonsensical, seriously rational and utilitarian, answer, for looking for somebody else's home world, we need to do some fundamental research which seems to be virtually ignored. If you want to find the home world of some aliens, you need to figure out what characteristics of the planet and its star are necessary, and what other conditions there are, such as having a satellite, low eccentricity, large gas giants in the same solar system, axial tilt and so on. A simple temperature of water condition is foolishly simple. We need to find the conditions both for life to originate and then, completely separately, for an intelligent civilization to evolve. That's what this blog is all about, but much more could and should be done.

Aliens in Binary Star Systems

Can an alien civilization arise in a binary star system? This is not a relevant follow-on question to the principal one: Why haven't aliens visited us recently? It is one that is relevant to the hunt for alien civilizations from Earth, as if they won't come to us, we'll have to go to them. It is important to build some filters to separate out solar systems where aliens might be found, versus ones where they certainly can't have originated. After an alien civilization has mastered interstellar flight, they could go to any solar system they want, which makes the hunt more challenging, but if we are trying to find ones where they could have originated and specifically not where they might have seeded themselves, we can come up with some sharper criteria. So, could there be an alien home world in a binary star system? We don't want to spend precious telescope time on the impossibilities. First off, even if a binary or multiple solar system has a star which is suitable for origination, a G star like our sun, or sometime close to it, an F or a K star, that doesn't mean there aren't difficulties for life origination. When we see a binary, a physical binary of course not just a visual binary, if the companion star, or one of the companion stars in a multiple system, is a large star, we know that the age of the solar system is too young to have aliens, as these stars do not live very long. For example, even a mid-class F star, like an F5, doesn't last long enough for life, at least if evolution is as slow there as it was on Earth. Thus, both stars must be smaller than about a F7. If the other star is a white dwarf, this is also a bad sign, as white dwarfs are the end-stage of stellar evolution. It means that at some time in the past, they went through the red giant stage, then ejected most of their matter and collapsed to a white dwarf. A planet around a binary companion of this process would likely experience severe disruption, and any life that had originated on that planet would be either terminated or put through some severe extinction processes. While somehow life might re-evolve after this if the white dwarf process had concluded billions of years in the past, it would seem more fruitful to look at binary systems which have not endured the end-stage of stellar life. The next requirement is for stable planetary orbits. Three classes of orbits can exist in a binary system. One is where the two stars are close together, and the planet away from the pair of them by many times the inter-star radius. If you were such a the planet, you would see the two stars at once, circling each other. A second class is one where the planets are around one of the stars, and the other star is far distant beyond any planetary radii. The third is everything else. Your imagination can run wild here, with orbits making figure eight loops or some sort of modified oval around both of them. Clearly the discriminating ratio is the inter-star distance divided by the planetary radius, or for complicated orbuts, the mean distance over a long period of time from the planet to either of the two stars. If this ratio is very small, you have type one, very large, type two, mid-sized, type three. So far, it does not seem there has been a Kepler for type three orbits, and so we don't have a nice classification of them, along with the limits for stability. We hardly have the limits of stability for non-binary solar systems, so this is hardly unexpected. Type three orbits are better left ignored for now, although some computations could be done fairly easily to search to see if there are any weird orbits that are stable in this category. Type one orbits have a different problem. With two stars circling each other instead of a single star, a planet will fell much more of a tidal pull. In other words, two close co-orbiting stars will tend to transfer angular momentum out to the planet much quicker than a single star could. Since angular momentum increases with radius, this means the planets would be driven outward and eventually dispersed. Maybe that would be billions of years, but for life to evolve, a planet needs to be in a near constant orbit for these billions of years. The good-for-life situation is that a stars stays quiet and constant for eons and the planet is in a stable orbit. Alternatively, the planet could slowly drift outwards as the star becomes hotter with age; both of these processes happen quite slowly and fortunately go in the right direction. This matching is not something that would likely work with a type one orbit however. This means that we should look for planets hovering close to the star, meaning also that binaries of interest must be long-period binaries, the hardest to detect. In other words, if we already know a star is part of binary star, it is a poor candidate for an origin-of-life source because we can only identify short-period binaries with our current telescopes. Earth's astronomers have not identified many binary star systems yet, compared to the number of nearby stars, but somehow an estimate has been made that a third or half of all stars are in a binary system. Hopefully for the existence of aliens, these are mostly very distant binary systems. To use Earth as an example, we might have a binary companion star, maybe another F class, at 50 thousand AU, nearly a light year out, and it would not have prevented life from evolving here. At five thousand AU, perhaps it would have, and there is some boundary of influence that remains to be calculated, once we actually figure out how life originated, that is. To do a better job at identifying binary star systems in the neighborhood of our sun, we need bigger telescopes. Perhaps a verey large one at an Earth Lagrangian point could be used to develop btter parallax readings on nearby stars to get their distances and proper motions more exactly. One out at a Saturn Lagrangian point would be even better. There is little hope in simply watching far-separated stars to see if they circle on another. The type of orbits we are looking for, where a planet can be safe to originate life, means the two stars circle with orbital periods of the order of a million years. This is the limit of permanent connection. Stars cannot be in binaries at several light years distance from one another, as other passing stars will exert too much influence and destroy the orbital containment. So, distances of a tenth to a half of a light year are what to look for in a binary system where aliens can peacefully live and develop their civilization and hopefully star travel.

Nearby Black Holes

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

Heavy Elements in Galaxies

One question relating to the geological separation of useful mineral ores on exo-planets, something critical for an alien species to develop technology and socially evolve into an alien civilization, is about the distribution of heavy elements around the Milky Way. If a exo-solar system evolves from a gas cloud with very little heavy elements, above neon for example, it might evolve life on a suitable origin planet in that solar system, but the aliens, after becoming intelligent, wouldn't find the metals they need to go from a stone age to a bronze age, and they would never develop an advanced civilization. Thus, in order for us to have visitors from a particular exo-solar system, it has to have formed out of the same set of materials in the gas cloud, approximately, as Earth did, or maybe one which was richer in heavy elements.

These heavy elements are thought to be produced in supernovas, of which there are multiple kinds. Stars are nuclear ovens, gaining energy from nuclear fusion, which produces the elements above helium. Larger stars burn nuclei up to the nucleus with the least energy per nucleon, iron-56, but the kinetic process of showering nucleons into nuclei produces a wide distribution, centered around iron. Other phenomena produce heavy elements, and may produce a different distribution than burning in stellar cores. One example is the merger of two stars, in particular, neutron stars. So there can possibly be multiple sources of heavy elements, but they all involve stellar fusion processes or stellar disruption processes.

There are very few observable supernova in our galaxy, and probably very few stellar mergers as well, down in the number of a few per century. This rate cannot have produced all the heavy elements we see today, so the rate of production must have been much higher in the early galaxy.

Galaxies may form from the condensation of gas clouds of appropriate size, and as they condense, there are fluctuations in density leading to places where individual stars can form. As the enormous, galaxy-sized gas cloud condenses, if the density is relatively large compared to our current location, large stars will form as opposed to small ones. Large stars invariably turn into supernovas, and the largest of them might even totally explode, rather than just the outer layers exploding. The center of the star will be almost all heavy elements, with iron as the center of the distribution of elements, and larger stars may be more likely to have completed more of the fusion, so the central iron-dominated core will be a larger fraction of the total stellar mass.

This means that during the first phase of galactic evolution, long before the disk evolves to carry away the angular momentum of the cloud, the gas will be large homogeneous, or at least homogenous in spheroidal layers. The disk will form from the outermost layers of the galactic gas cloud, and thus we might expect that the disk will be fairly homogeneous with respect to the amount of heavy metals that exist in the disk and spiral arms. Thus, to a very coarse first assessment, solar systems close to ours might be expected to have the same distribution of isotopes and therefore elements. So, unless we want to think of stellar travelers coming from distant parts of the galaxy, the initial fund of elements should be sufficient on origin-type planets to allow any civilization which develops to get past the stone age, and move onward to industrial development and past that, provided that the geological separation processes on their exo-planet were sufficient to allow the useful elements to collect into bubbles within the molten core, and drift out to the crust and condense there into a solid.

The crust of an approximately Earth-sized planet does not have to be stable. Lying just underneath it is a hot molten layer, which may be in motion relative to the crust. Why? Because tidal pulls on the crust and on the molten layer are different, and induce a differential motion. Tide does not affect different materials the same, and a molten layer might move differently underneath a frozen crust. The crust might be flexed, and molten material leak upward, in what is called a basalt flood, if it is large and spread over an area, or a volcano, if the leak is confined to just a crack in the crust.

It would seem that a moon, during its early days of being much closer to the planet, had yet another task to perform that would be useful to an alien species which would arise much, much later. It causes a mixing of materials between the upper part of the below crust layers and the crust layers. If the two of these are each filled with different ores, the upper surface, where alien miners might get to it, would have an even better mixture of elements than there would be on a planet without a large moon initially close into the planet.

Often solid materials are more dense that liquid ones, and thus the crust, if it breaks into fragments, might be denser than the upper part of the layer below it, which might be called the mantle as it is on Earth. Then any cracking of the crust would allow part of it to sink down slighly, providing an opening for mantle materials to move upwards, and cool. There would be a balance between these materials cooling and becoming more dense, and the pressure inherent in the mantle both pressing them upward and condensing them to higher density.

The iron core would be largely elemental, but the condensing minerals would be combinations of metals and anions of various kinds, as there would be plenty of these elements in the initial cloud as well. The proto-planet would have elemental carbon and oxygen, which might combine to form a carbonate with some metal. And so on for all the other types of compounds found in ores. It might even be that the gas cloud, which has some percentage of dust mixed in it, already has some beginning compounds, and these partially remain intact during all the condensation and heating phase of planetary formation.

It would seem that the best way to explore our local galactic neighborhood for planets containing life and also alien civilizations would be to improve our telescopes and other detectors, and look for an Earth sized planet, located in a stable orbit relative to the other planets, and with a large moon locked into a orbit around it. Of course the stable orbit must be in the liquid water zone, have some axial tilt, and not be in too elliptical an orbit, which may be implied by the stability of the orbit, unless there were no large planets in the solar system.

This tangentially raises another interesting question for our exo-planet astronomers: are there any solar systems which have only one planet? Or is this an impossibility due to some feature of the mechanism of planetary formation? We on Earth have detected only one planet in most of the solar systems we have so far discovered, but that is not the same thing. It would be fascinating to find out there were many like this, with one planet only. This revelation would mean that we have less guidance from our home solar system toward understanding what goes on in other ones.

Futurology and Alienology

Futurology is a name coined back a half-century ago, meaning the science of predicting the future. It may be obsolete now, but the idea of predicting the future has been around since man first figured out the difference between the past and the future, during the beginning of intelligence. It was always a way to get personal benefits. If you could talk to the gods and get the future from them, you could command a good position in your clan. If you were an erudite historian in the Middle Ages, you could talk about all the historical precedents for the present time, and what history says will happen again. In the fifties, it was chic to use statistics and various listing techniques to develop some semblance of a science. It was also common to assume that the average impression of lots of people was better than the insights of any one of them, and so survey techniques became common, with questions all about what the future might have. None of this made any sense, but it did make some good salaries. Back then computers were somewhat novel, and the idea of modeling and then simulation of something became an obvious outgrowth of them. There was little concept of the individualistic nature of a model, and it was thought that there was something intrinsic to some part of nature or society that would appear in models. Even now it is not at all understood that a good modeler can make almost any output come out of his model of whatever it is you wanted modeled.

Alienology is a name used in this blog for the attempt to use other types of scientific methods to analyze what parts of the development of an intelligent alien species were mandatory and which ones were stochastic. It may have been used elsewhere for other purposes, maybe cataloging movie aliens or designing creatures or documenting what some impressionable individuals have reported about their purported contacts with aliens, or whatever. One of the motivations of alienology, as presented in this blog, is to answer the question of why aliens haven't visited us. This question has been around since someone first conceived of the idea that the stars in the sky might signify other worlds like our, complete with people of some sort or another. Buddha included this concept in his teachings, back two and a half millennia ago, so the question is a very, very old one. Buddha's writings were recorded because he was revered as a great teacher, but all those other people from two or three or more millennia ago who said the same thing did not have their comments remembered. The question is more than old enough to have been answered already, but like many other subjects, there wasn't enough science back then, up to a century ago or so, to provide any reasonable way to credibly answer it. Now there may be.

The techniques used for alienology have been described in several other posts, except for one. That is morphology, which was invented by Swiss-Czech/Bulgarian scientist Fritz Zwicky, who also is responsible for many things known by children everywhere today, such as supernovas and jet engines. He used his technique of morphology for these inventions, and wrote a book about it. Morphology is simply the idea of listing all the possibilities for any option, in a scientific concept or engineering invention, and investigating them one by one until the one that is best emerges. It is methodological investigation, and of course has some difficulties, such as how to you define the criteria or attributes of the object you are going to list possibilities for. This involves a way to categorize objects, or rather, everything, on multiple levels.

This becomes an almost intuitive tool for those embracing it, and alienology does this, by questioning assumptions and asking what other alternatives might there be, and then investigating them equally, with an open mind. It is the opposite of learning the best answers for questions, and then building on them, and instead is more of a tearing down of best answers than building on them; then these best answers might occasionally get replaced with something different. The novel theory of the origin of life introduced in this blog is the result of this process, and the concept of swarms of black holes is another. There are indubitably many others buried in the blog. Morphology is one of the principle tools of alienology, along with technological determinism, the concept of asymptotic technology, and others.

This is all well and good, but what about futurology? Predicting the future of mankind would be a great blessing, but it is largely impossible, as there are so many stochastic events which affect the detailed course of future history. However, alienology states that the broadest flows of any alien civilization, of which Earth is an example to any other alien species, have a discernable outline. Thus, what happens next year or next decade cannot be aided by any derivation within alienology, but perhaps what happens next century or next millennia might be, or following morphology, there might be a list of possibilities which are exhaustive.

Mankind up to now has had very little interest in the far future, so the importance of anything alienology can say to futurology might be very tiny. You can't invest for stocks based on what happens three hundred years from now. You can't prepare for social change if you can only figure out what the social system might be a thousand years from now. So, as a practical matter, alienology is useless. There is no magic key that will help futurology become more relevant and less foolish.

Are there any benefits at all for life on Earth from alienology, except to answer the question of where aliens are and why haven't they showed up here yet? There are, but they are subtle. If they help a few of mankind's deeper thinkers spend some time on questions of the far future, instead of only the near future, then perhaps some improvement in the direction humanity takes toward that future might be obtained. Mankind seems to care not a whit about their decendents a thousand years from now, and perhaps that might be changed so that some planning is done with them in mind.

War and Technology Development

We use the word 'war' in alien civilizations to mean the wanton destruction of alien persons and property for the purpose of having one faction, likely one region on the planet, dominate to some extent another faction. It would be possible to have physical war and economic war, both done for the same reason, but with different means: one based on whatever weapons were available on the planet and the other on whatever financial arrangements were used on the planet. Mostly we discuss physical war here.

One question is whether war would be inevitable on every alien planet where the civilization reaches or exceeds the industrial stage of technology development. Another question is whether this is positive or negative toward the final result of being able to build starships and visit other solar systems, or at least seed them or do something there.

War on Earth has occurred since history was started, and likely long before. The scale has increased with technology improvement, but the idea of one group killing and destroying another has likely been around since before intelligence evolved. There are Earth predators who defend their hunting territory from predators of the same and similar species, and if an alien society began the climb up in intelligence, it would likely become a predator of some sort. Other motivations might exist among early alien species as well, involving mating or some outgrowth of the mating rivalry that exists in very many Earth species.

The growth of intelligence does not happen unless there is some benefit to the species for having it, and that means, in early species, more food most likely, or preferred shelter or something else. More food means becoming more of an omnivore, and one of the earliest technologies, fire, enabled a wider variety of food. So predatory behavior is likely and an outgrowth into intraspecies battles is not a wide step for evolution, social and genetic, to take. This expands to war between larger and larger groups. Control of larger groups is a likely outgrowth of control of a clan or tribe, and so war arises.

Does it persist, or might the alien civilization conclude there is little benefit to it and declare a never-ending truce between all factions? This is, of course, not a real question but a sham one, as it assumes that civilizations make decisions and conclusions, when actually it is individuals who make decisions with whatever brain they have evolved. The real question is, among those who control factions on an alien exo-planet with a civilization of some level, do they decide to direct their members into a war or not? Some decades ago, it was fashionable to think of the reasons for war and do statistics on various aspects of Earth factions to try and determine some insights. Now, that is seen to be foolish, as it ignores the mechanism by which wars are initiated.

Let's make a list. An individual alien might want his faction to go to war against another particular one for some emotional cause. If war is itself the end, it might be that the individual grew up as a bully, or the equivalent among aliens, and simply enjoys this concept and draws pleasure from doing it on a large scale. Alternately, it might be that the individual grew up in an environment which favored physical fighting among young aliens, and so the idea would be to have a war against some other roughly equivalently powered faction, meaning region. These are the 'bully' and 'boxer' motivations. One favors decidedly weaker opponents and the other, roughly equivalent ones.

The other side of this is that war might be only a means to some other personal end for a specific decision-maker, such as personal wealth, revenge against some individual high up in another faction because of some unforgettable insult, hatred against another faction because their policies do not please the decision-maker, gaining advantages by means of the processes involved in war for the individual or some subgroup within his faction that he is a member of and wishes to have excel over other subgroups within his faction, secret hatred for his own faction and a desire to see it weakened by the war process, and so on. This list is much more extensive than the war as an end list, but the point is that there are myriad reasons that a particular individual might wish for a war against a chosen opponent.

Would these lists be empty on an alien planet? It sounds impossible, given the evolutionary sequence that it takes for a species to become intellgent tool-users and problem-solvers. So, our simplistic analysis indicates that there would likely be a period of development, starting early and ending somewhere around the time when neurology is well understood and politics stops being controversial and becomes a search for effectiveness.

The second question is, is this warring positive or negative for the alien civilization for reaching the travel-to-the-stars era of their existence? Time passes in the alien civilation, and technology develops, moving it forward from era to era, but it also involves, in later stages, the consumption of easily available resources. Technology enables more resources to be available, and provides more energy to be consumed in the process of obtaining and using them. Resource use goes at a rate related to population growth and the achievement of efficiency in using them, as well as the living standard averaged over the planet. If technology development goes very slowly, resources might become exhausted, to the existing accessibility limit, before new technology is available to increase the amount accessible. This means the civilization burns out and collapses to a level corresponding to sustainability on renewable resources, most likely solar photons.

On the other hand, if there is warfare, technology for weapons will be a very highly prized object, and funding will be diverted to accelerate technology development. Of course there will multiple spill-offs from this, not the least of which is the production of trained scientists, engineers, manufacturers and designers. War uses resources and accessibility questions would be part of the researches done for war-fighting. Thus, one of the principal causes of alien civilization collapse too early for star flight, resource exhaustion, would be ameliorated by having a steady diet of warfare, probably one conflict every generation or two, until the limits of weapons of mass destruction is reached and warfare becomes too costly, except on a local scale.

Thus the conclusion is clear, war is likely to exist on most alien exo-planets during their later, but not latest, stages of technology development, and it is possibly a significant contributor to their staving off resource exhaustion, at an early accessibility level, until asymptotic technology is reached and resource exhaustion is put off until much later. If the civilization is fortunate enough to be on a resource-rich planet, this might mean they will have the option of space travel of some sort.

Geological Separation on Exo-Planets

In order for an alien species to proceed upward through the various stages of technological development, finally arriving at the top level, asymptotic technology, where it might start a starflight project, it has to have access to resources of many types. Energy sources are of course on the list, as without abundant easy-to-obtain sources of energy, the aliens cannot move into the industrial phase of development. Without large areas of fertile soils, they cannot even get far into the agricultural phase, and are forced to languish in the stone age until they become extinct.

There are more. The industrial era needs some mineral resources, such as iron and other metals, and as the age progresses, more and more elements and compounds are needed. The history of technology on Earth might be written as a history of materials and their availability, and it is the same for any alien species on an exo-planet. For example, one cannot have the massive computational capability needed to move into the artificial intelligence phase unless there are the unique materials needed for processors and memories, as well as other electronic components. On Earth, we started with vacuum tubes, which only require some glass, tungsten, copper and maybe a few more. But one cannot get far into heavy duty computation without the invention and deployment of transistors.

Where do all these materials come from? Some are directly obtained from mining, and others are produced from mined ores and their derivates. Hydrocarbons have to be included as a mined material, as many products include hydrocarbon derivates. Would these all be available on every exo-planet?

Not all dust clouds in the galaxy are equal. Before a star condenses and forms a system of exo-planets, it receives the residue from some supernova explosions, which are the accepted generator of higher atomic number elements. A huge tsunami of neutrons comes rushing out of the stellar implosion, and these build up existing elements to ones higher in atomic number. A particular gas cloud, prior to condensing to a star and a planetary disk, might have had a large number of large supernova and therefore be very rich in elements, or it might have not been so fortunate, and the star condenses with a planetary ring having little iron and the whole slew of other useful elements in it. This means the planets cannot have rich resources for any alien species which develops intelligence on one of them. It is not clear why an alien species could not develop on such a planet, so it could be what we call an origin planet, but it is one which will never have an alien civilization that could build a starship to come and visit Earth.

We should do some surveys, if we haven't already, and see if the galaxy around us is filled with very rich-in-resources clouds or if there are some that are and some that are not. That is one piece of astronomy which would help answer the resource availability question, but it is not the only one needed.

The other half of this question involves the accessibility of resources. Suppose we have a planet which condensed from the inner part of the disk where there were lots of resources, and the free hydrogen and helium all escaped, leaving a planet like proto-Earth. Does geological separation into the crust automatically follow? The planet upon condensing would be molten, from the huge release of gravitational energy, and it would be radiating its energy outwards as heat, gradually cooling. The outer surface of the molten droplet would get cooler faster, as the cooling happens faster than the conduction of heat from the interior. So a crust forms, but does it have separated ores? Ores need to be separated to a large degree, or they are inaccessible to the aliens.

If we had, on Earth, exactly the same set of elements in the crust, except they were not separated out but the crust was fairly homogeneous with a little of this and a little of that, in roughly the same proportions, everywhere, there would be no use in mining. There would be no point in searching all over the planet for some concentrated source of some industially important material, as it would be everywhere in tiny concetrations and nowhere in large concentration. Thus geological separation of various ores is a critical and mandatory requirement for the development of an advanced alien civilization.

We have one example to examine: Earth. We need to know if Earth is unique or ordinary, as far as geological separation is concerned. There can certainly be all kinds of degrees of this, so ordinary covers a huge plethora of types. There could be an exo-planet, with an even higher degree of separation, so at different points on the surface of the crust, there would be mountains of cobalt ore, or mountains of germanium ore, and more and more. Or it could be that an exo-planet has the same ores as Earth, but they are just smaller in amount, and harder to obtain. There is a question of the cost of accessing these ores. They produce some benefit to the alien society, at whatever stage in technology development it has reached, and if the benefits are small compared to the cost of mining, processing, refining and transporting them, they would not be mined. The society would not have them around to develop new applications and new technological uses, and therefore new technology. With costs of obtaining resources prohibitive, it is just as bad as if the primordial gas cloud was less rich.

Do we understand the process of geological separation of ores, quantitatively, so that we can compute some estimates of the existence of large, low-cost deposits on other exo-planets? When condensation happens, everything is mixed together, and immiscibility in the molten drop, perhaps mostly of iron and those elements which mix well with it, will lead to a separation. The ores which separate out, condensing somewhere in the molten planet, and which have density lower than that of the drop itself, will rise up to the crust, where cooling is taking place. These bubbles of molten ore might reach the crust anywhere, so the crust could have any type of ore anywhere. How big do the bubbles, which are concentrated in a few elements, specifically metals, with some carbonate or sulfate or other anion attached, get? The ones which are lower in density move upwards faster, but do they have time to grow larger? The slower the rise to the crust, the longer the time for a bubble of ore to grow. Several ores might be tangled together, leading to a mixed ore region, but that might actually help in the cost of accessing them. If the crust cools too fast, they don't rise up to near the surface, but are stuck below where they are too deep to practically dig out. What would keep a proto-planet from cooling to fast? Tidal friction from a large moon, in close.

The Earth, as far as we can tell now, is unique in that its moon is a large mass fraction compare to other satellite-to-planet ratios. Did the tidal heating from the moon, shortly after it was formed in a planetesimal impact on the proto-Earth, keep the crust hotter and thinner so that ores could form in large volumes more easily? If this is so, there might not be only one reason why a large moon is necessary for an advanced alien civilization but two: life originates with the moon's influence and ores form in larger quantities with the moon's influence. What an astronomical coincidence...

Can Bioterrorism End Alien Civilizations?

'Terrorism' is used here to refer to small-scale groups attempting to achieve some political ends through the use of terror attacks, which are attacks designed not necessarily to cause great destruction, but to induce terror in a significant part of the population of a target region, which will then bow to the political demands of the terrorist group. Technological determinism says that technology dominates social change, and it may also dominate terrorism, one facet of a civilization.

In the early eras of technology, where knives and poisons were the only available weapons, assassination was the only type of terrorism that could occur. Directed against leading members of the alien civilization's government or economic structure, a terrorist group could hope that concessions might be made to their cause if the leadership felt unable to protect themselves. Infiltration of the ranks of those with guardian capability might be one of the social tools such a group might use, and suicide attacks might inspire the terror they needed to accomplish their ends. 

The invention of controlled combustion might lead to projectile weapons, but these simply make assassination easier. Bombs, however, open up a new avenue for terrorism, and that is attacks on infrastructure or on the public themselves. These weapons have the most effect in crowded places, and the obvious countermeasure is control of those entering these places, with some sort of measures designed to detect such explosive packages, along with the ability to carefully search the areas, arenas or whatever places a particular alien civilization likes to attend in large numbers, to eliminate such weapons from being installed and hidden prior to the crowd's arrival, for places with sporadic use. Continuously used places would have continuous checking in place or lockdowns during non-used times of the day. 

The advent to nuclear technology, in the middle of the industrial era, does not change much for terrorism. Nuclear weapons are very difficult to design and assemble, requiring specialists of many varieties, and terrorist groups are unlikely to be able to obtain such a quorum. They also require multiple unique materials, some very difficult to make from other, more easily available ones. Since nuclear weapons contaminate great areas of any planet where they are used, all regions on any exo-planet with an advanced alien civilization would be motivated to cooperate in restricting access to these end-materials. The costs of a nuclear weapon program are great, and if terrorism is something small groups would use, they would neither have such resources nor be able to deploy them, if they found a donor. The weapons are also large and hard to move and hide, and they give off telltale radiation, which can serve as another means of detection. Thus, the advent of nuclear technology into the collection of useful technology does not make terrorism any more powerful or easy to apply, just the opposite.

The beginnings of biology, specifically the biology of infectious organisms, may be a different story. The ability to capture an existing infectious organism, and mutate it, requires little money or expertise. Even a single talented individual alien might do this as the technology is not complicated to understand or utilize, once society gets some basic knowledge into its storehouse of scientific understandings. Recall that psychology and neurology come later on, so that the ability of the society to detect some mentally disturbed alien, having such a capability, is limited. This means that an alien society in this particular phase of its industrial era can be victimized by individuals or small groups who concentrate on contagious organisms. 

This capability exists even below the level of a terrorist group. Curiosity or some sociopathic desires could motive individual aliens to explore what they could do in this area, as there may not be any knowledge yet about how to train young aliens to prevent their involving themselves and others in dangerous activities when they grow older and more informed and educated. Neither would politics be a solved science by this time, so there may be personal or political disputes that could motivate such talented individuals.  They might develop some organism, protect themselves and those they care about, and release it to see what happens. If it was based on an infectious organisms, the mutated version might be contagious as well. 

If amateur biologists can create mutated viruses, what could a terrorist group do? They might be able to operate in two stages, one: where they try all types of viruses in different locations to see which ones might serve as a terror weapon, and two:, bioweapon where they induce some cases of their chosen infectious organism into some locale that they have access to. 

A bioweapon attack, even on a small scale such as a terrorist group could manage, requires social controls to be put in place, rapidly and severely, if the contagion is to be controlled at a very low level. Those regions which can do this might be relatively immune to bioterrorism, but those which are not, for any of several reasons, could be held at risk by a bioterrorist group. After one or several bioterrorism attacks, it might be clear to all regions that they need to prepare themselves against such attacks. One way might be to scour the whole exo-planet for biology laboratories that bioterrorists might exploit, but since they can be quite small and do not need exotic unique materials, finding them all might be difficult. The other way, if the region has the resources and the governmental excellence to do this, is to organize a reaction to any attempts at bioterrorism, all the while reducing the locales at which it could be done. 

If these countermeasures against bioterrorism, in attacks or in threats of attacks, are quite expensive to a region, it might try to negotiate its way out of them with one or more bioterrorist groups, but since they can form easily, this might not be a long-term solution, and the expensive countermeasures are the only solution. If the costs are so large that the alien civilization suffers a reduction in affluence, in living standards, and in the means of survival, then perhaps the civilization will begin a slow collapse. 

The other solution that might be taken is technological suicide, where the alien civilization as a whole seeks to ban biological knowledge from being gathered, collected, or disseminated. This means that asymptotic technology will never be reached, the ability to diffuse bioterrorism will never be accomplished, and the civilization will go into stasis and collapse. A solution near to that is to strongly limit the knowledge of biology to tiny numbers of aliens, in the hope that this knowledge will not diffuse out to potential bioterrorist groups. This would seem to be a more rational solution, as it allows work on automatic generation of antidotes and antigens to continue. Thus, bioterrorism might certainly slow down the progress of an alien civilization, but it is unlikely to destroy it, and would therefore not be the method by which aliens are prevented from reaching Earth.

Biowarfare and Alien Civilizations

Warfare has been so common through the last several millenia on Earth that it might be thought to be inevitable that it would occur on all exo-planets with thriving alien civilizations. The killing of other individual aliens and the destruction of their property, on a large scale, can be motivated in many ways. It might be the equivalent of envy, hatred, greed, love of destruction, desire for power, wishing to spread one's world-view or religion, fear, and likely others. Since there are so many reasons for having a war, wouldn't there necessarily be some?

The antecedents of mankind's love for war might be their evolution as hunters. Killing large game and killing other aliens is not so much of a jump in direction as eating only fruits and vegetables and then starting to kill other aliens. Can only omnivores evolve intelligence and eventually a civilization, or could herbivorous creatures do so as well? 

Perhaps this question should be asked in a reverse manner. Can herbivores who develop tree-climbing ability and then grasping appendages stay herbivores, or would the ability to reach nests start them on the path to eating eggs, newborn animals, young animals, and lastly full-grown animals? Raiding nests on the ground might start them off on the same evolutionary track. Given the nutrient value of eggs and young animals, this track provides significant advantages, and therefore it is likely that such creatures would not stay herbivores, but would evolve, step-by-step, into hunting animals, and then into tool-using hunters. This is the likely step before killing one another, and then as groups form, so does the concept of warfare. Warfare is therefore likely in the history of most alien civilizations in the galaxy.

Technological determinism says that society is shaped by the level of technology it has achieved. Warfare, as one feature of society, is also determined by technology, and as technology travels from stone and wood tools, to metals of ever increasing strength-to-weight ratio, to combustion in various forms, and onward to machinery, so do the tools of war. In the later stage of the industrial era, on planets with uranium in the ground not already decayed into too much U-238, nuclear weapons should be invented, and then the society would quickly realize the disutility of weapons of so much destructive power and requiring so much expertise to use. 

There is likely an overlap between the genetic era, when biology is being understood in many of its details, a precursor to genetic technology, and the last stages of the industrial era, that of electronics, automation and robotics. Breeding of plants and animals would have been proceeding for the whole age of the society, using trial-and-error techniques, and as the understanding of disease becomes widespread, the concept of bioweapons does also. One can use trial-and-error methods to breed disease organisms as well as socially useful organisms. Initially, the analogous use of bioweapons would be tried, similar to chemical weapons, such as by explosive canisters or sprays, applied on the front lines of armies, but these methods have quickly-discovered drawbacks of self-contamination and countermeasues, such as personal protective equipment.

Contagion is a more appropriate use of spreading a bioweaponized virulent organism. If one region has a particular and unique type of crop, which provides a substantial fraction of the nutrition for this region, then an enemy region could attempt to devise infectious organisms which would spread widely through the crop, eliminating its value. If the crop was annual, the yield would plummet. If it was a perennial, the productive plants would fail to grow the product, or even die. No such type of attack would work if all regions grew the same range of crops, however. Analogous arguments would work for animal husbandry as well.

If there was some unique genetic characteristic that most of the inhabitants of one region possessed, and it were possible to breed an infectious organism that would only attack those inhabitants with the particular feature in their genes, an analogous attack could be made. However, if this genetic dissimilarity is not wide-spread, or no organisms can be made to focus on one that exists, biowarfare can only be accomplished through a more organized and insidious means. If contagion is the means by which the infectious organism spreads, then the attacking society must somehow have some characteristics that allow it to be only slightly affected, which the opponent must have the opposite characteristics. If the disease is mediated by insects which live in unhygienic environments, a hygienic region could attack a unhygienic one. The reverse is obviously not true, but if there is any infection-carrying options, such as pets of some particular type, these might serve as the vectors for the disease contagion. 

If the disease spreads only from dead bodies of victims, then burial details might make one region more susceptible to being the target of a biowarfare attack. However, this is something that could quickly be recognized and altered, so such an attack is problematic at best.

If the disease spreads only through direct sharing of bodily fluids, such as blood to blood, it is not likely that it could be transformed into a bioweapon. There might be the equivalent of Earth's mosquitos on some particular exoplanet, but insect control is not difficult in an industrial civilization. Thus these diseases also would not serve well as bioweapon candiates. But if the disease could spread through indirect sharing of bodily fluids, or even without bodily fluids being used on the whole transmission path, then there might be a possibility of a bioweapon. If the infectious organism can spread through touch, or live on any kind of common surface for a period of time long enough for mutiple aliens to touch it, or travel on dust particles or water micro-bubbles, then the disease could act to have a large degree of contagion. 

If the attacking region has a way to prevent such sharing because of social customs or other social controls, and the target region has different customs or no ability to install social controls, then the opportunity for a bioweapon war might be possible. It would not look like any other type of war, as there would be no battleground or front lines, no armies involved in mass attacks, no industrial war machines being used, and perhaps even no declaration of war. The only thing that would happen would be one region would succumb to a high level of fatality, while another would not. Then economics would finish off the struggle between these two regions.

Could one or more biowarfare wars doom an alien civilization to collapse and never reaching star travel? This is not likely to happen, as social controls can defeat a bioweapon attack or serve as a protection of an attacker, so society might have some economic disruption during the period of the attack, but the attacker would not lose their grip on technology, nor suffer a great deal of economic disruption, and would be able to control the other region or regions and continue to pursue technology and eventually get to asymptotic technology. After this point, infectious organisms are easily controlled and no biowarfare would make sense, as antidotes and antigens could easily be generated as soon as the infection was noticed.