Saturday, April 7, 2018

Time Horizon Shifting in Alien Civilizations

When alien species initially evolve intelligence, the use of the intelligence is to deal with problems in the present. Food, predators, reproduction, competition all require an intelligent response to maximize success. This predilection for immediate gain or benefits lasts for a long time, as there is nothing in the society to change that. Achieving some short-term benefit brings physical and social rewards, which means that sort of thinking, that time horizon, will be psychologically rewarding. It will stick around.

The long term thinking that might occur during this period is that of leaders or other important people, who want to see their offspring do well, and plan for the early portions of the lives of their offspring, so as to provide them opportunities. If the civilization is divided into warring factions, some long term thinking might go into strategizing how to best secure a good position, or any of a number of other options that arise in warfare scenarios. But there is little thinking about their own species in the long term, as a whole. One faction may be thinking about immediate steps to assure a good future of their faction, but the time scale is likely to be a generation or so.

This type of thinking will lead to the near-total exhaustion of their planet’s resources, or if they are fortunate enough to have a solar system where resources are economically obtainable from one or more other planets, asteroids or satellites, of the whole solar system’s resources. However, if the thinking in the civilization was centered about how to have their species exist for as long as possible, at a high technological level, they would have to have a very different attitude, that of conservation, recycling, reliability and reuse. The switch to this type of long-term thinking, which might have a span of many thousands or even a million years, is an important event in the history of the civilization. The switch over is such an important event in the history of an alien civilization, it should be given a name. Let it be the Horizon Transition.

If the Horizon Transition occurs late in the history of the civilization, when resources have already become scarce and substitutions are occurring to cope with shortages, the result of it will be to prolong the life of the civilization somewhat. If it occurs early, the civilization will have many more resources at its disposal for the later millennia of its existence. Since space travel is a powerful consumer of resources, this means that an alien civilization which is, for some reason, asleep to the important considerations of resource scarcity until very late in their domain of existence, it will not be nearly as likely to be able to travel to other stars, seed life, establish colonies, or any other tasks as one which was very early astute enough to recognize the peril that scarcity is.

Thus, if we find ourselves in a galaxy with many civilizations on other planets, but only a few have even traveled to the nearest solar system to their own, we might attribute that to the blindness that a civilization, coming from an evolutionary past, has toward the Horizon Transition. That means that the question of how a civilization stumbles on this important problem and figures out how to deal with it is an important one for alienology.

It is already clear that all alien civilizations are forced by their evolutionary past to be short-term thinkers when they enter the technology climb. Intelligence gets better and better, and it makes their short-term thinking more and more efficient and pointed. When does the leadership of the civilization state that it is no longer enough for the aliens to worry about what will happen next year or next two years, but instead, they need to consider what will happen in the next five thousand years? Why would they? It represents a tremendous value shift. They would have grown up worrying about their own wealth or status or power or security or something else, or that of people related to them or somehow connected to them, not imagined people of some large number of generations in the future. Why would a leader give up a concern for those whose interests he works for and replace it with a concern for those who will live long, long after all the current aliens have died? It makes almost no sense to think they would.

Instead, resource exhaustion will cause some effects, regulated by whose short-term gain can best be improved by the use of some of the tools to conserve or reuse resources. This means that it will be a piecemeal effort, resource by resource, as they each grow more and more scarce. This type of effort will not result in the substantial prolongation of the civilization’s future. Only a massive switch, the Horizon Transition, can do that, and there are powerful forces that must exist, in every alien civilization, that will prevent one.

How might such a transition occur? If resources are still abundant when living standards reach a high enough level, there will be a diminution of interest in short-term gains. In the spectrum of individuals in an alien civilization, there will be those who can never have enough material goods to satisfy their psychological needs, but the large majority can be satisfied. At this point, if there is some influence, some leader, some call for a Horizon Transition, it might be possible that one could be effected. Thus, if the population of the civilization does not grow as fast as the growth in living standards, as generated by the various technological innovations and revolutions, then living standards on the average can increase. If the alternative is true, population growth, in response to living standards rising, stays high, then this situation cannot arise, and a Horizon Transition cannot happen. This means that, unless population numbers are somehow restricted, it would be much less likely that an alien civilization would be able to afford a major project to travel to another solar system. Thus, the Horizon Transition question leads to a population growth question, specifically, what influences the growth of a population. In other posts, the problem of idiocracy was discussed, and that might be the deciding influence. This is again a topic for further thought.

Friday, March 23, 2018

Experiments Before Star Voyages

Once an alien civilization has reached asymptotic technology, and has made the decision to spread their species or life itself to other solar systems, they wouldn’t just build a rocket and launch it. There would be some specific experiments they would need to do before they felt confident enough to launch. The cost of an interstellar voyage has to be very high, and so there would be the necessity to prepare for it, including testing as much as possible, before any commitment was made to a single chance.

Estimates made elsewhere in this blog indicate that an alien civilization might last, living at the highest technology levels and a high individual standard of living, for about a million years on the resources available within a single solar system. That is an order of magnitude number, meaning somewhere between a third and three million years, and the estimates are even rougher than that. The accuracy of such as estimate is irrelevant, in that what is important is the comparison of the time the civilization will last to the time necessary for a space voyage.

If we take the distance to their target solar system to be related to the density of stars in a spiral arm, something like a hundred to a thousand light years is the range. This estimate might be very low if they are looking for a planet which already has a burgeoning ecology, where they would be able to land and fit in immediately. If it is true, as has been indicated in this blog on other posts, that life is hard to originate, then looking for another planet with life already evolved up to vegetation and animals might take them across the galaxy. If they are only looking for a planet where they could seed life, and have it evolve on its own for a billion or two or three years, then the shorter distances would be relevant. Their goals can be either of these. For the goal of starting life, they would realize that they would become extinct or at least reduced to a primitive level, very, very long before they could migrate to the seeded planet, but their goal would include the expectation that evolution on the target planet would result in something like them, given enough time.

Travel speed is a question, but given the monstrous amount of propellant and energy that are needed, assume an upper limit of 0.01c. This means they will have to prepare a ship to travel without breaking down for ten to a hundred thousand years, and then function in a very intricate way to drop their cargo off on the chosen target planet. We on Earth have a few things which still work after a hundred years, but our learning technology is so recent, we haven’t had enough time to have built something that would be tested for a thousand years.

Things go wrong over long periods of time that do not go wrong over short periods. Things go wrong in space that do not go wrong on a planet. Consider the simplest thing, the hull. It is going to have erosion at the front end. Going at 0.01c means that every piece of dust hitting the hull is going at that speed, relative to the ship. This is a vaporization level of energy. There is very little dust outside of solar systems, but there is some, and dust clouds may exist that the aliens do not know about. Can they map all the dust clouds, and if they could, can they steer a ship moving 0.01c around them without insane amounts of additional energy and propellant? Even individual atoms and molecules will abrade the front surface of the hull, and there are clouds of hydrogen in the galaxy just as there are dust clouds.

What does ten thousand years of exposure to galactic cosmic rays do to a steel hull? A single cosmic ray, meaning high energy proton, will most frequently splash some electrons around inside the first millimeter of hull. There is a lesser chance it will displace an atom or two in the steel. The degrades the crystal structure, and the outer layer of steel will grow weaker and weaker. Small nanoparticles may come off, especially if the angle of penetration is far from perpendicular. This is simply another avenue for erosion of the hull, and it works in combination to dust particle erosion by weakening the hull prior to the impact of a dust particle, which can then remove more mass.

Besides erosion, what goes on in a material like steel if you just let it sit still somewhere for ten thousand years, in a non-corrosive environment? Is there very slow migration of non-iron atoms, so that the material becomes less homogeneous, and therefore less strong?

To figure out erosion, experiments with a high rate of dust and particle flow could be done in a laboratory. It should be possible to do these experiments over a relatively short period of time. To do the chemical segregation question, temperature might be used as a surrogate for long periods of time, but just how accurate this is is not clear. Certainly, observing some metals, semiconductors, amorphous compounds and other single materials for a thousand years at different temperatures might completely solve this problem, and allow the alien civilization to extrapolate to ten or a hundred thousand years.

This sounds straight-forward, and with the alien civilization having a million year horizon, a thousand year experiment doesn’t sound too bad. If they found that certain materials failed after a few centuries, then a series of experiments might have to be done to try various solutions to the problem. There goes another few thousand years. It is hard to see how the requirements to evaluate reliability and fix problems in this arena would take more than some tens of thousands of years. This means that the experiments to prepare the materials and equipment for the ship might be done in the first ten percent of the expected time of their existence, and that the need for experimentation would not prevent an alien civilization from traveling to another planet and at least seeding it with life.

What might overturn this simplistic conclusion is the finding that there was some very difficult engineering problem that was related to extremely long periods of time. For example, there will have to be some embodiment of intelligence in the ship, in order for it to decelerate correctly to the target planet, go into orbit, and prepare its cargo for descent. It might be guessed that nothing organic would last that long, so DNA and some entire cells would have to be created by scratch once the ship gets to the target solar system. Can a thinking automaton be built that will continue to correctly function for that length of time? We think of automation as involving semiconductors used in computation and data storage. These could be shielded from cosmic rays to a great extent, but there would have to be something connected with the ship’s systems that the shielded computation system would have to manage. How would the external system survive? If a mechanism is conceived which will unpack the automaton after a hundred thousand years, how is this mechanism supposed to last? What system will be monitoring the location of the target star and tell the ship when it is time to do the final deceleration?

Thus, the very first guess at what would be a very difficult engineering system might be the external ship sensors and data processors for them. Can the ship be run as a dead lump, with the entire automation apparatus enclosing itself inside a suitable shield, and then emerging after exactly the right amount of time? In other words, would it have to be engineered so that the first part of the trip, the acceleration, and the final part of the trip, the deceleration to orbit, would be done with the automaton exposed, but for the large majority of the trip, inside a shield? This means the propulsor would have to be much larger than for a continuously operating trip, as all the acceleration would have to be done in a short time.

How is energy going to be stored for thousands of years and then become available? If the automaton hides inside a shield for almost the whole trip, it must have some energy inside to at least run the clock and figure out when to open the shield, and then to run the mechanism to open it? Or should the shield be a labyrinth instead of a box, with no direct path to outer space which does not pass through a thick wall, but plenty of ways to snake connections out?

It seems that building a ten thousand year ship can be considered today, and that our knowledge of science and engineering might be enough to produce some ideas that will help us determine if such a ship could be built – a sort of feasibility thought-experiment. Such a thought-experiment would help alienology determine better if there are any very long term experiments that would have to be run. Another interesting challenge...

Tuesday, February 13, 2018

Civilizational Collapse Prior to Asymptotic Techology

Intelligence is like a magic bullet. By intelligence, we do not mean literacy, like the familiarity with a hundred ‘classic’ works of literature. Nor is it numeracy, like knowing how to solve calculus and set theory examples. It is problem-solving ability, which is completely separate from literacy or numeracy, except that they can serve as tools for the problem-solver in his quest to overcome some difficult parts of a problem. Problem-solving takes place every day in every society, as when a person decides how to fix an appliance or substitute cooking ingredients. This is the low level of problem-solving, not involving anything new, just solving a problem that many others have solved before. The high level of problem-solving occurs when no one has solved a problem before, or at least no one in your tribe or city or wherever it is that you might learn from. It is like figuring out how to put a pointed rock on the end of a stick and reduce the threat of tigers by killing them more easily instead of running, climbing or hiding. It is like figuring out how to get somewhere faster by hanging onto the back of a horse and forcing it to go where you want instead of where it wants. It is like figuring out how to heat certain stones very hot and then use the metal that drips out of them. It is, in essence, pushing the envelope of how society used to do things into a region of more capability. It typically uses technology, in the broadest sense that includes organization, management, and delegation just as much as physics, animal husbandry and metallurgy.

If society collapses for some reason, famine, war, volcanoes, pestilence, or something else, intelligence cures the problem, sometimes only low-level and sometimes high-level, perhaps re-inventing something that was wholly or partially lost. Basically, the ability to solve problems with intelligence is an almost universal cure for civilizational collapse. It can’t cure extermination of course, but most lesser problems involving either population reduction or environmental catastrophe are eventually solvable, generations in time perhaps, or even centuries, but sometime. What can’t be solved? In other words, what problems can’t intelligence solve? This is the question that will answer the more formidable problem of “Would alien civilizations collapse prior to reaching asymptotic technology?”

Intelligence can’t solve problems that involve the destruction of the intelligence necessary for problem-solving. In other words, we have a tautology. If there is no more intelligence in a society, no more technology would get invented, some might be lost, and society can collapse. So, how could intelligence be destroyed across the board in a whole civilization? More specifically, how can the level of intelligence capable of solving higher-level problems be destroyed? If a civilization maintains lower levels of intelligence, capable of solving lots of lower level problems, it might get to statis, a fixed state of civilization, and never go forward to asymptotic technology. If something happens to an alien civilization that allows lower level intelligence to flourish, but eliminates some necessary factor for higher levels of intelligence to occur, it will hit stasis or collapse. The numbers of individuals who do higher levels of problem-solving are very few, so it is not necessary to have any widespread slaughter of anyone who can read or anything like that, it is only necessary to remove from society those mandatory, but possibly unknown, factors that allow some low level smart person to develop his mind and become a genius able to solve some hitherto impossible problem.

Intelligence comes from two factors, genetic and environmental. The highest levels of intelligence need contributions from both of them. If smart aliens stop having young aliens, in the period before the genetic grand transformation and industrial gestation is possible, then the genetics side of intelligence will fail and this particular alien society will fall into stasis, possibly never reaching the genetic revolution, or into collapse and descend into some earlier state of living at a lower technology level. If an alien civilization simply does not recognize the absolute necessity of having a requisite number of high-level problem-solvers, or does not understand the genetic lottery that produces them, they could collapse without even understanding what is happening to them. Consider an alien born into an alien civilization which is in the industrial revolution stage or perhaps in a later stage of it or beyond it. Suppose this alien is one with some portion of the genes necessary to provide a young alien with the total complement necessary to become a genius problem-solver. The alien is not a problem-solver, as he does not have the full complement, and the only way to get to a full complement is to breed with some other alien who also has a partial complement. This assumes the alien species is bisexual, which seems to be a reasonable assumption of evolutionary convergence, meaning that’s how it has to happen on any planet with evolution, and therefore Earth is a good example of it.

If either the partial complement alien decides not to have offspring or decides to breed with someone without a partial complement of genius genes, he will produce no high-level problem solvers for the next generation. So, if the alien civilization could either not reward having offspring, or need these partial complement people, who have mid-level intelligence, for other tasks, or promote breeding between partial complement people and no complement people, or in any other way interfere with the genetic lottery producing super problem-solvers, then the civilization can collapse. Maybe after it collapses, it can recover as the discouragement processes are terminated, or maybe it does not collapse that far but maintains the traditions of the former ‘golden age’, meaning no high-level intelligences or too small a number to matter.

The other side of the coin of intelligence is training and education. If training for problem solving is abandoned, such as by training everyone to only a low level and not allowing the best to fulfill their destiny, the alien civilization could just as easily sink into a slow collapse, with the collapse time measured in generations. Alternately, the alien civilization could disparage problem solving and laud such things as power over others or physical skills or humor or anything else other than problem-solving, so that those capable of this were seduced into never using their skills.

In short, it is certainly possible to devise ways in which the magic bullet of high-level problem-solving is never fired, or fired such a few times that the noise of society eliminates any benefits of some problems being solved. Known solutions could be forgotten, or even worse, disparaged for some reason or another, and then even stasis would not be possible, only collapse. If it is a real possibility that any alien civilization will run into this morass, and sink below the sea of mediocracy, then this is a potential answer to the question of why they never came here. The reason is they foundered in idiocracy, but of a peculiar type: they only got rid of the few who could carry their civilization to higher levels.

Sunday, February 11, 2018

Invasive Species on Alien Worlds

Invasive species are simply those species that are transported from one region to another region with a similar environment, where they can out-compete the native species. This usually means they can eat what is available if it is an animal, but there are no predators for them among the native species. They have free rein to survive and multiply fast, and even to drive some native species into extinction. Plants colonize some areas, spread rapidly, and choke out native plants.

Since it takes a long time for a predator for these plants and animals to evolve from native species, or for the prey to develop means of surviving them, there is often a large overshoot of population, which is what leads to the extinction of the prey species, or the pushing out of native plant species from whichever type of habitat the invasive plant can occupy. This invasion of non-local species has probably been going on for billions of years, but recently mankind became involved, by being the vector by which the animals or plants travel to their new location. They might go on ships or airplanes, or be brought as decorative plants or pets, or via many other human interactions.

Humanity’s response to noticing this is to sometimes try to eliminate the invasive species, which rarely but occasionally works or at least serves to keep down the population of invaders. Mostly it is simply given up as a hopeless problem. Maybe someday there will be some robotic or genetic technology to restore an ecology to the way it was before mankind introduced the invasive species, but for now, there is none. People just see it as a sad situation.

Invasion can also occur at the microbe level, but that would be mostly invisible to humans. The exception is when the bacteria or virus involved preys on humans. The “Black Death” in Europe, killing off a large fraction of the population, was an invasive bacteria transported by trade from Asia, where it was endemic. Similar die-offs happened when diseases common in Europe arrived in the Americas. We also see these invasions in our food crops, where some monoculture is affected by a fungus or a virus or something else microscopic that lived in some wild area, but found the monocultured crop to its liking. Because of the immense investment in food crops, these invasions are often met by the best killing techniques technology can offer, or alternatively genetic alteration of the monocultured crop to resist the invader.

On any alien world where tectonics has divided up the land mass into regions, or climate has, there is the same possibility. An alien civilization would seem to be likely to make the same introduction of non-local species and see the same result. If the civilization had passed the agricultural grand transition, their food crops might be affected, leading to occasional widespread famines. If, later on, they were interested in preserving natural areas, with native plants and animals, they could easily find themselves victimized by some invasive species from another part of their world. Perhaps they would have found some solution in a bit higher technology that we possess or perhaps they would be forced to regard the problem as much too expensive to cure. Being able to build robots that can hunt down some invasive predator and kill it might mean too much expense on these robots, or side effects might happen. They might just have the same response that we do: sadness and resignation, and a set of techniques or preventive methods to minimize the number of occurrences.

When an alien species becomes intelligent and climbs the mountain to asymptotic technology, the ultimate stage of technological capability and knowledge, and generates for itself the ability to travel to other solar systems, will this experience affect their thinking? Will they ask themselves: Do we want to make ourselves into an invasive species? This is the exact opposite viewpoint that nations have used when exploring other parts of our world. "We are bringing our culture to new regions." Is that what the alien civilization would want to do, or would it instead just stay at home, trying among myriad other projects, to keep some of its remaining natural areas undespoiled by either its own intrusions or by invasive species from wild areas in other parts of the globe?

Recall that, if technology becomes available to travel to other stars and start a civilization on other planets, exo-planets (to the aliens – it might be Earth to us), the question as to where to go and if they should go becomes one of culture-wide philosophy or psychology. We on Earth can’t easily deduce what answer they will come up with, as we have stalled in our search for asymptotic philosophy, the end-all answer to philosophical questions. We are still circling around trying to figure out what philosophy is and what questions it should answer and how to integrate our knowledge of the universe into it, and many, many other aspects which we haven’t elucidated yet. It seems weird to say that we should be studying philosophy in conjunction with harder technologies if we want to coherently answer the questions of alienology, which is figuring out in the abstract what an alien civilization would do, as well as how it would develop.

The question that would face a potent alien civilization of whether they want to become a conquering people or an invasive species, which is exactly the same thing just with different points of view, or they want to stay home until something happens to exterminate them, is an essential one. We already have deduced that this question would be asked and answered in an alien civilization around the time it was passing through the genetic grand transition, because in conjunction with that would be a set of breakthroughs in neurology and training. These breakthroughs would enable those having the most influence on the alien civilization’s path forward to cast their opinions into the repetitive training that new generations would receive, and have these teachings, which we call memes here, preserved for very long periods into the era of asymptotic technology.

Sunday, February 4, 2018

Non-gaussian Bell Curves in Alien Civilizations

Numerate people are familiar with the bell curve. It is a simple result that crops up in elementary probability and in the translation of its results to some simplified genetics. If you have some quantitative attribute, like height, and have a number of genes that contribute to it, each with their own amount, and then you have a gene lottery in which these genes are selected randomly, the population will have a distribution of heights that looks like a bell. There will be a median height, and heights above and below it will drop off according to the gaussian curve. This has its limitations, as obviously there would be no aliens with heights ten times the median, but it is a good approximation.

If aliens on some planet reproduce bisexually, as do all higher organisms here on Earth, then there may be a complication which arises if there are genes which both affect the external quality, such as height, and also the success of a haploid cell in the fertilization process. If there is a positive correlation, such as between height and haploid success, then there will be more embryos with genes that contribute to more height, and the resulting bell curve will bend toward taller individuals. The opposite result happens if there is a negative correlation between the attribute and haploid success of cells containing genes which increase that attribute. If there has been convergent evolution between the alien planet and Earth so that the alien species there reproduce with sperm-egg meiosis, any genes which contribute to the viability and fusion success of either the sperm or the egg will have some evolutionary advantage, and also those related to motility of the sperm. If these genes also affect an attribute, such as height, there might not be a gaussian bell curve, but instead a bell curve following a different formula.

These results are an effect of a double function of a particular gene, and double functioning genes that affect two attributes can also result in a distorted bell curve. Thus, even before environmental effects are considered, there can be non-gaussian bell curves for some attributes.

The external environment can have an early or late effect on the success of a particular gene or combination of genes. These effects are part and parcel of the fitness tests that evolution provides to each planet to improve its gene pools, or better said, to adapt its gene pool to a particular local environment on the planet where some species inhabits. The attribute distribution curve after each particular test will be affected by the results of test on survival. If height improves survival of infants and toddlers, it will be selected early, and after this test there will no longer be a bell curve of the exact gaussian variety, but a distorted one. For example, if very short individuals do not survive the litter of a species which produces large litters at each birth, the curve of heights will be clipped at the bottom. Similarly, if height is a disadvantage, for example because of increased caloric requirements, the curve will be clipped at the top.

The more interesting phenomena is when an attribute, in an individual’s interaction with the environment, affects itself in a kind of feedback loop. Consider height of juveniles of a species on some alien planet, where there is competition for food, and consider that height assists in the competition for food. But also consider that an increase in food intake in a juvenile individual results in more growth. Then what we have is the upper tail of the bell curve stretching itself out toward even taller individuals. If an infant of the species has won the genetic height lottery, it is then more capable of out-competing others who did not, and it becomes even taller because it has obtained more food, which in turn has increased height all the way to adulthood.

There cannot be too many examples of attributes which can interact with the environment to increase themselves, but perhaps there are some important ones. Consider an alien immune system which becomes capable of resisting more infectious organisms by some means if it is successful in doing so. To be more clear, consider an alien species which has several immune responses to infections. One of them grows more capable each time it conquers an infection, but the others do not. An individual with a better set of genes for the first type of immune system will conquer more infections with it, and that system will grow stronger and more capable each time. If it were possible to measure immune system overall capability, the distribution curve would be stretched out on the high side because of this feedback effect.

What might make a tremendous effect on whether an alien civilization climbs to the pinnacle of technology, giving it interstellar interests and possibly capability, is the attribute of intelligence, specifically not literacy or numeracy but problem-solving. This variety of intelligence is what drives a civilization toward heights of technology, while the others play a supporting role. Suppose that the environment of an alien civilization, in its primitive stage, is such that intelligent individuals with higher problem-solving skills can be trained or can train themselves to have even greater problem-solving skills. One might imagine a civilization in which bright individuals, meaning ones which solve problems in a displayable manner in front of their parents or mentors or whatever they use, and is therefore rewarded by being given the opportunity to learn more tricks and techniques for solving problems. Alternatively, just imagine that doing problem-solving is a inherent learned skill in the higher levels, but is genetically based at the lower levels, and an individual with a high lottery score in the genetic basis of problem-solving has opportunities to learn and improve on his or her or its own. Then, with this feedback loop in place, the civilization will have a continual supply of individuals who can advance technology at different eras in the civilization’s history.

This concept, of environment providing positive feedback to intelligence genes, may be a deciding factor in whether a civilization progresses continually or does not. For example, it will be worth considering if a society at different stages of its progress will support such feedback actions or will dissuade them, perhaps totally inadvertently, before it understands the importance of what it is doing. In other words, can a civilization kill its own progress before it understands the requirements for continued progress?

Wednesday, January 24, 2018


There are a lot of headlines about exo-planets. It would seem the general public has a modicum of interest in whether there are other planets on distant solar systems, and the continual addition to the collection of known solar systems or at least some selection of planets of distant solar systems keeps the interest up. One of the more prevalent news stories is about how some telescope or some astronomer has reported some super-Earth hundreds of light years from us.

There is a selection effect, in that small planets are harder to detect than a larger planet would be in the same orbit. Larger planets induce more wobble in their parent star and cause a bigger reduction in light when they fly in front of the star. So far, not many planets of the same size as the Earth have been found, but there are multiple super-Earths, which are planets only a small multiple of the mass or diameter of the Earth. This will certainly change, as budgets permit even higher resolution telescopes to be constructed and turned to the search for yet more exo-planets.

There is one Earth-sized planet that seems to be largely neglected, Venus. Venus is almost the same size as the Earth, both in mass and diameter. It is located about 72% of the distance to the sun as Earth, meaning solar radiation is about twice as much. From this alone, Venus should be hotter than the Earth, and it is, but the temperature difference is greatly exaggerated by the fact that Venus has a carbon dioxide atmosphere about a hundred times the mass of Earth’s. This produces a great greenhouse effect, which helps to explain why the equator of Venus has something like 465ºC, rather uniformly because the thick atmosphere spreads the heat.

Venus and Earth would produce identical signals to some alien world watching our star, using the same kinds of instruments as we currently use to find exo-planets. The same mass means that the wobble induced by Venus would be the same as that induced by Earth in the same orbit, and the same diameter means that Venus would block as much of the sun as Earth in the same orbit. So the conclusion from this is that when an astronomer issues a press release indicating they have discovered another super-Earth, or even something similar to Earth, they could just as easily produced a press release saying they discovered a super-Venus, or something similar to Venus. Atmospheres are quite thin compared to the diameter of a rocky planet, so it will be a while before reputable measurements of the atmospheric mass are available, which is what would be needed to directly discriminate between a Venus and an Earth in some distant solar system.

There are two explanations for why the atmospheres of Venus and Earth are so radically different. One might hark back to the formation of the Earth, during the first period of bombardment by asteroids, when a large planetoid is believed to have impacted the Earth, producing the moon. This impact might have blown off much of the atmosphere during the impact, and even more might have been ripped off if the moon started out its life in an orbit very close to the surface of Earth, from which it was torn. Venus has no moon, and it might be quite unlikely that such an impact, with just the right masses, velocities, and miss distance center-to-center, would happen to other planets in other solar systems. If this hypothesis is correct, we should be detecting super-Venuses instead of super-Earths, and soon, Venuses instead of Earths.

Another possible mechanism is that life ate up all the carbon dioxide in the atmosphere of a primitive Earth, producing oxygen in its place, creating the lightweight atmosphere Earth now has. This hypothesis has some difficulties. If there was an Earth with a huge carbon dioxide atmosphere at the present Earth orbital radius, it too would have a greenhouse effect that would raise its temperature above that where life could form. The older sun was somewhat less bright, but not that much less bright so as to allow this form of atmospheric modification to occur.

Just consider for a moment the situation in the galaxy if rocky planets forming in solar systems like the one we inhabit almost invariably have heavy carbon dioxide atmospheres, and there is rarely a situation with the right type of planetesimal collision to strip it down. Using our G2 sun as an example, if there was a Venus-like planet at Earth’s radius, there would not be life because of the high temperature, which means no aliens and no star travel. If there was a Venus-like planet further out toward Mars or even beyond, there would be a range of orbital radii where life could survive. A Venus-like planet in that range, if it somehow originated life, might have the same phenomena happen as happened on Earth: carbon dioxide disappears and oxygen appears. Exactly how so much carbon dioxide goes away might be a further question, but just suppose life is potent enough to have this happen almost completely. But when the carbon dioxide goes away, into rocks or sediments or living creatures, the greenhouse effect diminishes, and the planet gets colder and colder.

We had an ice age on Earth, nicknamed snowball Earth, which did not kill off all life. Quite possibly there was an equatorial area where there was no ice cover. But if Earth had been out at a Mars radius, the equatorial safe zone would likely not exist. The whole Earth would be a snowball, ending the chances of life surviving and evolving. And it would likely stay that way. Thus, one option for the non-existence of aliens traveling to Earth and giving us their business cards is that all the planets out in these distant solar systems are Venuses, too hot for life, or snowballs, too cold for life. Earth, with its fortunate collision four billion years ago, somehow was transformed into a planet where life could both originate and evolve. Perhaps there are other planets like ours, with a moon lingering as evidence of the collision, but the numbers would be drastically less than the count of super-Earths (really super-Venuses) would indicate.

Sunday, January 14, 2018

Colonizing Mercury

An alien civilization might want to attempt to preserve its own chance of survival, as a species, in the event of some monstrous calamity, such as an asteroid of large size smashing into the planet. One form of insurance is to have a colony somewhere which would not be affected by the catastrophe. It would be nice if there was another planet similar to the home planet in the same solar system, maybe a bit hotter or colder, but close in attributes to the home planet. If there is no such planet, what do they do? What types of planets might serve as runners-up?

In our solar system, we have no such planet. Mars is the closest thing, and we talk about colonizing it someday. But in a solar system with no Mars, what else could they do? How about some planet like Mercury, close to the sun, with no atmosphere, maybe phase-locked with some resonance relation between its orbital time and its rotation time?

If there was some diffusion of heavier elements toward the sun inside the pre-planetary disk, it might be that there is more of the iron-and-heavier elements there. This is not necessarily a good thing from an insurance planet point of view, but it is if you want to mine these resources for some other purpose and make the insurance goal a subsidiary to the mineral exploitation one. To simplify, let’s just consider the insurance goal. Mercury has a reputation for being hot, due to its location near the sun. This is true, in general, but not completely. Mercury rotates in a 3:2 resonance between rotation and orbit, which means that it has a solar day twice as long as its year, 176 earth days. The temperature along the equator rises to about 425ºC at the subsolar point, but drops to -180ºC on the dark side.

To colonize a planet, and have the colony be self-sustaining, it must have two things, energy and resources. If a Mercury-like colony cannot be self-sustaining, then it is of no use as an insurance planet for an alien species. Mercury certainly has energy to spare. A water tank at any latitude other than one near the poles will cycle between steam temperatures and ice temperatures. It doesn’t take much imagination to design something to produce power from this temperature cycling. Suppose there is a surface tank able to withstand high pressure steam, and underground, where temperatures stay closer to the average, another tank of the same size with a turbine between them, as well as a pump. During morning, the water in the surface tank turns to steam, spins the turbine making electricity, which is used at the time both to power the habitation requirements, and to create storable energy, for example, hydrogen and oxygen from water. During night, a set of fuel cells would convert the two gases back to water while producing energy. Water is pumped from the lower tank to the upper tank shortly after dawn and the cycle begins again.

Living under the surface means a more constant temperature in the habitable area. The average equatorial temperature is about 120ºC, meaning that would be the underground temperature, too hot for humans. The polar temperature is always about -180ºC and unless there was significant heating from the core, that would be the underground temperature there also. At some latitude between zero and ninety degrees, the underground temperature should be 70ºC, quite comfortable. Aliens might prefer a different temperature, but the basic idea of having poles very cold from virtually no sunlight and an equator heated up by intense solar heating implies there is a latitude where the average temperature is the one desired, and that would be the one underground.

The next question is: are there mineable resources there that cover the entire range of elements that the aliens might need? The follow-up question is, can they be mined at a sufficiently low cost so that everything needed for life can be produced, with energy to spare?

Mercury is very dense, more so than all other planets except Venus, and should have a wide variety of minerals. The proper questions would be asked about the light elements, those needed for life, such as hydrogen, carbon, nitrogen and oxygen. Oxygen is present in many earth minerals, as oxides, sulfates, borates, phosphates and carbonates. The last of these is a source of carbon, as are pure carbon minerals such as graphite and silicon-carbon combinations, specifically moissanite. Hydrogen is perhaps the most versatile element and is found in thousands of minerals. Nitrogen is the likely show-stopper, as it is much more rare than the others, yet critical for life of any sort we know of.

Thus the question turns into one related to the presence of elements necessary for life, especially nitrogen, at latitudes on Mercury near the comfort zone, and not too deep. Energy would need to be used for excavating, transporting, crushing, extracting, processing, forming, and manufacturing activities. Two key variables will control the answer to this question. What is the level of reliability that the alien society can achieve, as this relates to the redundancy count needed to ensure the colony never runs out of power or foodstuffs or any other critical material? What is the degree of recycling they can achieve, as recycling typically uses less energy than all the separate activities that are involved with obtaining a supply of fresh resources from underground?

In other posts, it was postulated that successful alien civilizations will stress both of these key variables. After some time, an alien society that wants to prolong its existence on its home planet will come to recognize that one limit on its longevity as a civilization is how much mineral wealth of the planet is wasted as opposed to how much is conserved. Reliability and recycling are the main activities that reduce resource usage, and there is no reason to think that these procedures, techniques and habits would not be easy to transfer from the home planet to an insurance colony on a forbidding planet like Mercury. Building in reliability and manufacturing easy-to-recycle products is not something that immediately will spring out in the civilization, but assuming it is sufficiently intelligent, it will happen, sometime around the time they go through their genetics transformation.

By the way, establishing a sustainable colony on a barren and hostile planet like Mercury opens up a wide range of options for an alien civilization which plans to travel to other solar systems. Mercury has some similarities to planets around dwarf stars, and what is learned from their experience with a Mercury-like planet may serve them well, as they can go to a much nearer star to establish a colony. Dwarf stars are the predominant type of star in the galaxy, meaning they are everywhere and close as well.

Saturday, December 30, 2017

Asteroid Defense

We live in a fairly benign solar system. Earth has not had a major asteroid impact for 60 million years, however, that one was an extinction event. Large asteroids hitting an inhabited planet can create large shock waves that sweep through the atmosphere, megatsunamis that can cover almost all of the land surface, dust to fill the atmosphere and block photosynthesis long enough for most plant life to die, vulcanism at the impact site or at the antipodal point, or simply pumping so much heat energy into the atmosphere that non-aquatic life mostly dies out, as well as near-surface dwelling sea life.

In a solar system with more frequent extinction events, with the events happening more frequently than the recovery time needed by life on the planet, asteroid impacts might simply result in almost uninhabited planets, with only single-celled organisms or perhaps small creatures remaining. Is it possible that these are the norm? If so, it could prevent any alien species from ever arising and taking on the job of traveling to other solar systems beyond their own. Earth, as an exception to this norm, would be alone in the galaxy.

Asteroid impacts consume asteroids. Each time an asteroid hits a planet or a satellite, it is destroyed and there is then one less asteroid to impact a planet later. Asteroids do not typically form after the formation time of the planets, so any period of heavy consumption will free up later periods to have periods long enough for intelligent life to form. Astronomers like to talk about the Early Heavy Bombardment, when there were many more asteroids than now, and very many of them were hitting planets and satellites. One might assume it was a sort of random process, and try to figure out the decay time of the rate. If it was short enough, an alien planet might become free of asteroid impacts early on, and easily proceed to evolve all manner of life. If it was long, meaning the cleaning process to remove asteroids did not work very quickly, asteroid collisions would be spaced out so that impacts, not being common initially, did their work for a long time.

Where the asteroids are, and what type of orbits they occupy, makes a great deal of difference in this cleaning process. If there were only a few large asteroids, and they occupied stable orbits in reference to a couple of shepherding gas giants, there would be no collisions, just like we do not expect Mars to hit Earth any time soon. The only problem is that this doesn’t work as well with tiny bodies like asteroids, as there is likely to have to be some dissipative forces to move planets into stable orbits, relative to the gas giants. Asteroids are too small to have enough of these, as they would go as a second power or higher of the mass of the asteroid. Thus asteroids just keep the orbits they were born with, unless they do a gravitational slingshot with a giant planet. They may be in the vicinity of a stable orbit relative to the shepherding gas giants, but not as close as a rocky planet or something larger.

The sweeping clean of orbital areas should be proportional to the cross section of impact, and a gas giant has hundreds of times the cross section for collision that a small planet would. Thus, those orbits which intersect the gas giant’s orbits are likely to get swept clean early on, but not the orbits which intersect the small planet’s orbit. The orbits from which a gravitational slingshot can happen are those which will be swept clean early, so the later periods of a solar system would be when asteroids were concentrated in the areas where there were minor planets, which are the ones where life can form.

Let’s do some numbers on asteroid collisions. First, suppose there was an asteroid in an orbit similar to Earth’s, fairly circular, in the same stable notch caused by the gas giants. That notch might be of the order of a quarter of the distance from the mean orbital radius of Earth to that of Mars. The cross section of Earth compared to the cross-section of the notch, assuming it is circular is of the order of ten to the seventh. If the difference in periods is about ten percent, this implies the cleaning of Earth’s co-orbital vicinity is short compared to the age of the solar system. But for asteroids not in co-orbit with the Earth, another factor, comparable to the radius of the Earth and the radius of its orbit, about a million, comes into play. This makes the cleaning time much longer than the age of the solar system, and implies that for some solar system like our own, with an Earth-sized alien planet at something like the radius of Earth from its star, asteroids will be coming for the whole lifetime of the solar system.

As soon as an alien civilization became expert at astronomy, it would realize this peril existed. Probably there would be geological evidence of the same thing. Thus, asteroid defense would be considered. Is it feasible that an alien civilization could prevent an asteroid from hitting their planet?

Destroying a larger asteroid is probably impossible, but fracturing one into two pieces might work for some of them. However, the destruction operation is likely to involve large amounts of explosive, which means that the resulting course of the pieces is uncertain. This would therefore have to be done far away from the planet to allow the pieces to go far wide of the alien planet. Other asteroids, larger ones, might be impossible to fracture. Diverting them would be possible, if their orbits were sufficiently precisely determined.

Before any destruction or diversion can happen, the asteroids would all have to be located and tracked. Those with the possibility of crossing the orbital radius of the alien planet would have to be tracked more precisely. Could the alien planet find the resources to do this? If the number of asteroids was in the millions and their orbits ranged over the whole solar system, they might not.

The other defense, a backstop to anything else, is to make self-sufficient outposts on other planets or satellites so that if there was a large collision with an asteroid, it would not spell complete extinction of the alien species. This raises the question of whether in a typical solar system, if a very competent and dedicated alien species could figure a way to sustain life on at least one other planet or moon in the absence of support from the home planet. Would doing that leave any signatures that could be detected from Earth with a sufficiently large telescope or other observing devices?

Saturday, December 9, 2017

Alpha Pair Strategies in Alien Civilizations

Many animals here on Earth use alpha pair strategies to control reproduction in times and locations where scarcity prevails. Primates, canines, birds, and others have been observed using it, and there are probably many others as well. In short, the strategy involves the formation of a group of one species, usually incorporating both sexes, which hunt or forage together. There is an accepted strategy for selecting an alpha pair, who are the dominant animals of the group. They get the first food and are the only ones or the preferred ones to breed. Others in the group may serve as assistants, or protectors or nurturers of the alpha pair’s children. There may be a second tier, the betas, who get some of the privileges that the alphas get.

This is not the same as territorial domination, but it may co-exist with it. With territorial domination, a pair, or a single sex of a pair, may take actions to exclude others of the same sex and species from hunting or foraging within an area controlled by the alpha. With the hunting region divided into territories, some animals of the species will get none, which is the equivalent of them not achieving alpha status and having reduced chances for breeding. The alpha pair strategy and territorial domination achieve the same goal over the long term: animals who can achieve dominance feed better and breed more. Successive generations will emphasize the traits involved in the competition, rather than traits necessarily concerned with survival in the environment.

Alien civilizations face the threat of idiocracy, or some other type of dysgenics, once they pass the industrial revolution and affluence takes hold. With a negative correlation between reproduction rate and any positive attribute, the average of that attribute will decline with time. The period between when affluence hits at least part of the population and the time when genetics is taken control of after the genetics grand transformation is when the population is vulnerable to this effect. It may be that no response is given, even that no notice of the problem exists in some particular alien civilization, or it may be that they debate what strategy should be followed to abate it.

The only government reproduction policy that has been effected here on Earth is the one-child policy by China. For the period 1979 until 2015, only one child was allowed for many women, and forcible involuntary contraception implantation or sterilization was used to enforce the rule. There were numbers of exceptions, allowing typically two children, in cases where a child was handicapped, or even if the first child was female. This policy had debatable results, as reproduction rate was already declining before the policy, and it has declined in some other areas which did not have such a policy. Most likely, it exaggerated an already strong trend toward lower reproduction rates. This type of policy is ostensibly neutral toward dysgenics, in that it allows the same dysgenic effects to occur as would occur without them, but perhaps reduces their effects by disallowing large families.

To control this problem, an alien planet might have a similar policy. But can alternatives exist? Is it possible that an alien population might be descended from pre-intelligent animals that employed the alpha pair strategy? Humankind’s exact ancestors are long extinct, but related animals, the higher primates, have strategies of this kind, or something similar, such as the bonobo’s alpha female strategy. When and why might it be lost, and would the same transition necessarily occur in alien populations on similar planets?

Reproduction rates on the gene or chromosome level are determined by two factors, survival of the individual carrying those genes to reproductive maturity, and then reproduction of the individual. The transition to a different reproductive strategy might occur with the transition from an individual hunter-gatherer culture to a clan hunting culture. Hunting large prey which requires the cooperation of a group of hunters means that there must be some tendency toward equality of activity or sharing of the rewards of the hunt. This sociological trend is referred to as the ‘big man’ strategy of food-sharing, in which status, and therefore leadership, is given to the person who arranges for others to eat. This means that survival to a degree is now decoupled from individual capabilities, and these capabilities are sorted out for reproduction in a different way. Individual hunters reproduced because they were good at hunting and therefore found mates. This might be correlated with strength or balance or tool-using ability. Group hunters all share in the spoils of the hunt, and leadership of the group is given to the individual who organizes the hunt the best. These qualities are mostly mental, although obviously good physical characteristics are needed. Thus, intelligence is supported if there is a breeding strategy that rewards the hunt leaders.

If the group is large enough, it cannot reproduce sufficiently if an alpha pair strategy is followed. Population will decline and hunting of large prey will become more difficult with a smaller group. However, if there is a multilevel hierarchy, and reproductive rights only go to the alpha and betas, then reproduction might be adequate to maintain the population of the group and allow it to continue to preserve itself and its strategy. This policy is vulnerable to the departure of the non-selected, either in pairs or in groups, in a schism of the group. Polygyny or polyandry would tend to make the formation of the schism less likely, as would the provision of food from successful hunting. If hunting is difficult, staying for the food might outweigh leaving for reproduction opportunities.

From what limited pre-historical resources we have, it appears that humankind shifted to a monogamy strategy early on, and did not follow any type of alpha pair strategy. This left them vulnerable to dysgenics unless there was not a negative correlation with capability, but positive. The positive correlation solves the problem completely. So the question to ask about is what leads to a negative correlation of productive capability with reproduction? To see if any of these strategies might be profitably used by an alien civilization requires some more thinking about the timing and causes behind the changes in human society.

Saturday, November 25, 2017

Crustal Fragments as Asteroids

Consider a solar system with a planet or dwarf planet somewhat smaller than Mars. If it is large enough, when it forms there will be a great amount of heat generated, meaning there will be separations of elements and compounds, and ore mixtures as well, in the core and crust of the planet. The largest glob will likely be an iron and nickel mixture, which would form the core of the planet. If it stays warm enough for long enough, compounds not very soluble in this metal will separate out, and assuming they are lighter in density, will rise to the crust. The crust will have all the interesting materials in it. The core will be fairly homogeneous, but the crust will have different ores separated out, provided the elements to make these up were there in the beginning.

Thus, small planets deep in the solar system, where dust would collect, would be treasure-troves of minerals, some of which might be very important to an alien civilization which had passed the point of being able to travel throughout their solar system.

As far as mining of inner, metallic planets goes, they do not need to be very small for mining to take place. Having no atmosphere may make it easier or harder to do mining, and that is not clear now. But smaller planets, with no atmosphere, would be vulnerable to the rain of smaller asteroids that happens in the early days of a solar system. Many of these would simply pulverize the surface. Those which came in on a grazing trajectory, if the size and speed were right, might chip off some piece of the crust and transfer enough momentum to it so that it escaped the gravitational pull of the small planet. This is a crustal fragment.

A larger planet could conceivably give rise to a crustal fragment asteroid as well, but via spallation rather than a grazing impact. If a large asteroid were to impact a larger inner planet, the shock wave from the impact would travel through the planet, arriving at the opposite point from the impact point. Perhaps it could have enough energy to blast some material past escape velocity, and possibly some of this material might still be intact, that is, some chunks of crust go flying into solar orbit.

Mining asteroids is thought to be a possibly profitable venture, in the sense that the retrieved material is worth more than the cost of retrieving it. For a crustal fragment asteroid, the materials might be much more valuable than an asteroid which simply has the average material of the solar system at some radius. There could be a hundred times more valuable ore on a crustal fragment asteroid than on a usual one. What would be important if finding which was which. This might require visits by some small robotic ship.

Suppose there was an asteroid, formed from one of the crustal fragmentation processes, which was of the order of a hundred kilometers in size. If it were explored, and there were sources of rich uranium ore in the asteroid, it might be able to form a self-sufficient colony of aliens there. Using the uranium as an energy source, the only energy source, could enough energy be generated to provide a habitable environment, where every other material had to be mined from somewhere on the asteroid and transformed into useful materials? If this is possible, a temporary colony could be established, either independent or part of some multiplanetary organization. How long could alien civilization last on the asteroid? Until the uranium ore was depleted so much that it could no longer supply the energy needed to power the entire asteroid and all its necessary activities, of mining, transporting, refining, manufacturing, and all the multiple activities needed to provide a habitable environment.

How likely is it that there would be one or more of these crustal fragment asteroids in an average solar system? We don't know what average is yet. We don't know what asteroids are in our own solar system, so the data is pretty sparse. At best, we can indicate it might be possible.

What might be the orbital characteristics of a crustal fragment asteroid? Ones which are formed from the grazing impact process would have something less than the orbital radius of the incoming asteroid, the one which hits the small planet. That could have been in orbit similar to the planet which was hit, meaning the resulting asteroid would also. However, in the early days of the formation of a solar system, some asteroids might be shot into orbits out of the planetary plane or even retrograde. This happens because of the interaction of the major planets with the small bodies co-inhabiting the solar system. It should be quite rare, but possible.

The spallation situation might serve to give the spallation fragments a higher speed that the incoming asteroid, if the shock wave was focussed sufficiently. Is it possible that it could be given solar escape velocity, and leave the solar system? Is it possible that later interactions with large planets could slingshot it out of the solar system? The later is certainly possible, and the former, maybe. Either way there is a process by which a crustal fragment asteroid could become an interstellar rogue. Since the crustal fragment asteroid is formed in such as way that its orbital parameters could be unusual, this is not too hard to imagine.

This means that for an alien solar system, there might be rogue crustal fragment asteroids passing through it, laden with massive amounts of uranium for energy and other crustal materials for manufacturing. Could an alien civilization, able to travel around its own solar system and very famiiar with mining asteroids, manage to get to such as asteroid before it passed through their system, and establish either a robotic colony or one comprised of some very brave colonist aliens? Only if they had prepared such spaceships in advance, so they could simply concentrate on getting their ship there and down on the surface in the months that the asteroid was present in their solar system.

They might be able to make small adjustments in its trajectory from solar system to solar system. If there were a sufficient number of this type of rogue asteroid passing through their solar system, it would mean that we should not be looking for some giant saucer-shaped ship for visiting aliens, but instead a large rock.

Friday, November 24, 2017

Rich Clouds, Poor Clouds

It seems that normal stars do not produce the amounts of heavier elements, those higher in atomic number than iron, that are observed in the galaxy. Some other source is indicated. One theory involves a collision between two neutron stars. This might be effected by starting with a binary with two neutron stars. In a binary with only one neutron star, it eats up the atmosphere of the other star. But a neutron star has no atmosphere similar to a normal sequence star, so one cannot strip mass from another. They have little to do but radiate energy and eventually collide, leading to another type of explosion.

This makes sense, as higher elements are formed by neutrons being added to lower elements’ nuclei, and a neutron star is nothing but neutrons. An explosion would lead to the rapid formation of elements, but the spectrum would be quite different from that of a stellar interior, where elements are kept in equilibrium by a very different set of processes.

One question this theory raises is how well a binary can survive a supernova explosion of one of the two stars involved. Perhaps a well-separated binary could survive it, with only a orbital change, perhaps from near circular to an orbit with large eccentricity. Would the first supernova strip off part of the atmosphere of its binary companion, reducing the amount of fuel for it to burn, and thereby hastening the second supernova? This theory of binary neutron stars raises many intriguing questions.

Binary stars do form fairly frequently, so it would make sense that some of them would have two stars which could both evolve into neutron stars. It’s not exactly clear what would happen if one of the stars became a black hole, just barely. Perhaps the same type of collision would also add to the heavier elements.

A fairly obvious question arising from this is: Are clouds uniform in the production of double neutron star binaries? Are clouds which are larger or smaller, more or less dense, more or less turbulent,more or less spherical, hotter or colder, dustier or more gaseous, more likely to produce these special binaries? There are many parameters by which clouds can be described, and it would seem some of these would affect the production of predecessor stars to neutron stars, and binaries to boot. If these factors do play a role in the relative density of these binaries, then around the galaxy there would be, sometime into the lifetime of the galaxy, clouds which are rich in heavier elements and clouds which are poor in heavier elements.

If the technology development of an intelligent species requires the presence, on the planet, of a certain amount of heavier elements, this means that some clouds in the Milky Way are more prone to civilizations which can eventually travel to other stars, and other clouds are too deficient to allow any intelligent species to climb high enough in technology to do this.

Clouds are much larger than solar systems or intersolar distances, so this means the galaxy might be like a large continent, part of which was habitable with rain and rivers and vegetation, while other large areas were barren deserts. Similarly, it would mean that travel within one’s original cloud might be much easier than from one heavy-element-rich cloud to another. Huge distances would have to be traveled, in comparison to the typical interstellar ones. Just to provide some food for thought, suppose the distance between good planets was 100 light years in a rich cloud, and the distance to another rich cloud might be 10,000 light years. While it might be reasonable to travel the first, the second might be simply too far. Thus, the galaxy would be necessarily divided into pieces which cannot communicate between one another.

The heavier element distribution is an additional galactic distribution factor on top of the diversity that already is known to exist, with different major components such as the bulge and the disk, and the variations known to exist in the disk with the rotating spiral density waves and the gulfs between them. Cloud density variations are huge to begin with, and with this latest theory on the peculiar ways in which heavier elements are formed, there is yet another factor contributing to the geography of the galaxy.

It should be possible for an advanced alien civilization to map out the distribution of heavier elements in the galaxy, using large wide spectrum photon collectors. They would therefore know, before they made any decision as to seeding other planets or doing anything else interstellar, just how much territory they could operate in. They might find out that they are in an extreme situation themselves.

If the density distribution of heavier elements is very peaked, in other words, the processes that make heavier elements, such as the proposed neutron star collisions, are quite rare, and there are only a few pockets within the galaxy where there are higher densities of these elements, then they might find that there is no hope to seed the galaxy. Basically they might find they were in one pocket, that there were no other similar solar systems within that pocket, and the nearest other pocket was on the opposite side of the galaxy, much too far to travel to under any circumstances at all.

This distribution may be yet another surprise awaiting Earth scientists as they explore the galaxy. Right now in our history we are just beginning to understand the galactic environment that we live in, and the question that has caught our fancy is the possibility of life originating on other planets. For this we search for some attributes which might be signatures of life. But it could very well turn out in a few years or decades that we realize that we are indeed located in a very unique corner of the galaxy and are the only ones alive and civilized at this time. The galaxy is too harsh a place for life to evolve and develop a technological civilization except in only a tiny fraction of the existing solar systems.

Another implication of this is that heavier elements might take billions of years to accumulate, so that if we had come into existence five billion years later, the galaxy might have many more alien civilizations, traveling from one star system to another or at least communicating between one another. It is too bad we can’t wait around for all the excitement to begin.

Sunday, November 5, 2017

Rogue Asteroids

In current news, it was reported that Earth astronomers have detected their first interstellar asteroid within the solar system. Temporarily named A/2017 U1, its size has not been determined, simply its trajectory. It traveled in from the north of the ecliptic, passed by the sun within Mercury’s orbit where the orbit was bent back toward the north, and on its way out of the solar system it passed within 25 million kilometers of Earth. This latter fact allowed it to be detected by our sky survey instruments, which are looking for near-Earth asteroids.

The size was bounded by maximum 400 m diameter, as otherwise it would be less faint. There is no albedo measurement, so the true size will stay unknown. Let’s throw caution to the wind, and try and understand the implications of this detection. If we say an asteroid with diameter between 300 and 400 meters would have been detected, can this be used to figure out the number which pass through the solar system? The sky survey telescopes can see this object out past 25 million kilometers, but perhaps not detect it initially. Let’s simply suppose that this is the only one of this size which passed through the sphere of detectability of this radius during the last twelve months. Neptune’s orbit is about 180 times this distance, so by looking at cross-sections, we might say that of 32 thousand penetrations of a sphere of this radius, only one would go through the Earth detectability sphere. This means that of the order of 32 thousand asteroids in this size range come through the solar system each year.

If we assume that the size distribution of interstellar asteroids is the same as the asteroids in our solar system, this size range represents about one thirtieth of the total asteroid population with diameters greater than 100 m. So, a little multiplication tells us something like a million asteroids bigger than 100 m shoot through the solar system every year. We’ve seen one.

This number could be off by an order of magnitude or even two. If the sky survey astronomers were really lucky, and this was the only asteroid to come through the detection sphere in a century, then everything would be 100 times too high. But the simplest guess is that this is not the one year when it happens, just that there was not much interest in such objects before, and the detection rate was affected by the attention given to them. Now things are different, and the sky eyes will be looking for the next one.

This asteroid could have been formed similarly to a orphan planet, just condensing out in interstellar space from a small cloud that congealed. Probably it was instead formed in a solar system, and then chucked out in the early days of orbital interaction. There could even be some late time interactions which propel an asteroid from a solar system. We don’t live in any unusual part of the galaxy, just a normal section of a spiral arm, and so it would be reasonable to assume that other solar systems have similar amounts of interstellar object penetration. What would an advanced alien civilization make of this?

One thing they could do would be to use the asteroids as free shipping objects to other solar systems. Put some memorial on an interstellar asteroid, and a million years later it might pass through another solar system. Stars move around a lot, so it might be hard to write something that would be meaningful as to where the memorial was inscribed, but perhaps that problem would be solvable if some dating were possible. Is there anything in the galaxy that tells time?  We can date supernovas and nebulae formed by them by determining the relative speed of the nebula gas, and backtracking the trajectory to find out the date when the supernova exploded. This might be accurate enough to enable some announcement in the memorial as to when the alien civilization inscribed it.

To get the memorial out to an interstellar asteroid requires some high-power propulsion. This asteroid we see is going at about 25 km/sec relative to the sun. For comparison, LEO velocity is 8 km/sec and it is still within Earth’s gravitational well. To comprehend better what launcher requirements are, think of putting a multistage rocket into space outside of the moon’s orbit. The payload of the rocket would have to include a lander, plus control systems able to bring it into orbit near the interstellar asteroid. This would have to be done within a period of a couple of months, between detection and departure of the asteroid. It exceeds our capability significantly, but we haven’t even been launching extraterrestrial rockets for a century yet. It should certainly be within our capability within another century, probably much less.

Digging into an asteroid would provide a radiation shield for anything that the alien civilization wanted to send to another solar system. Digging machines would mean a much larger payload however. It would be good, for such a massive mission, to have as much lead time as possible. However, doing a sky survey requires a telescope that can be oriented and scanned over large sky areas. Using a kilometer sized telescope rules out rapid scans. Thus, the task of landing on an interstellar asteroid and creating something there within the allotted time is certainly technologically challenging.

Could something more significant be done with these opportunistic travelers? Perhaps if there was a rogue planet nearby. If we assume the ratio of planets to asteroids is the same in those early solar systems that were launching asteroids as in our present day solar system, perhaps one millionth as many planets would get launched on interstellar trajectories as asteroids. So, there is some possibility that one will come by. It is also quite possible that the dynamics of planets is such that there is a much lower probability of launching a planet on an interstellar path than an asteroid, so the number might be a billionth instead of a millionth. If this is the situation, we shouldn’t expect a planet anytime soon.

If there was one, and it had an energy source such as large amounts of uranium ore, it might be possible to put a robotic colony on it that would be self-sustaining. It is barely conceivable that such a rogue planet could be used on a seeding mission, especially as there is no way to choose the target solar system or the arrival time. More likely, memorials will be the only thing possible for these star-traipsing asteroids and planets.