Friday, September 30, 2016

Chromosomal Selection

The genetic grand transformation is one of the big changes or revolutions in how an alien civilization is set up and what it is like to live in the civilization. The headline item on that, here on Earth, is changes in human beings. Science fiction has been written about it, it has become popular in the on-line press, and every scientific advance is coupled with hundreds of opinions about what it all means.

It is not likely that genetic grand transformation on any alien planet will start with the aliens modifying themselves. There are too many other simpler things, which would bring benefit to the society, which would be done first. The sum of all these things might make the eventual improvement of the aliens’ own gene pool easier to be accepted.

On any alien world, they would have been doing genetic modification, in an inefficient way, since the hunting grand transformation or at least the agricultural grand transformation, which are the first two of these transformations that shock the civilization into a new phase. Husbandry of animals, to make obtaining animal food much easier, started in one of these two, and to become a keeper of formerly wild animals, some selection has to be made. Animals of a particular species may vary in their acceptance of being corralled or penned, or in the case of tamed animals, their willingness to give up their former style of lives for a more certain food supply. The selection of adaptable animals is an act of genetic modification. There may be some non-genetic, experience factor in their adaptability, but there is also a genetic component.

Sowing seeds doesn’t necessarily involve any alien modification of natural genetic codes, but the next step of agriculture, where seeds are selected from desirable plants and then sown, as for a tree rather than something like a grain, does. Any act of selection of either the animal or plant on the basis of some desirable characteristic is an act of genetic manipulation, albeit rather clumsy.

This process of selecting improved or altered characteristics in animal and plant species simply goes on and on, becoming more organized, as the alien civilization progresses through its development. Selection becomes augmented by the creation of the variations over which the selection can be made. Two animals, each one with some desired characteristics and some less desired characteristics, can be mated, and the offspring sorted out to find one or more with more of the total set of desired characteristics than either one of the parent. Two plants can be cross-pollinated to attempt to accomplish the same goal: the collection together of multiple desirable characteristics. This is a slow and painstaking process. If the animals have a multi-year growth period before the characteristics can be reliably noted, then the cycle time for improvements is paced by this and must be slow. The same holds for those plants with an annual or longer growth cycle.

Because of the uncertainty of the mixing of the genetic codes from two individuals of the same species, there might be many generations of the species before the desired improvements are obtained. And even then, the process may be inefficient in another way as well, the improved animal or plant might not breed true, and the characteristics are not reliably transmitted to subsequent generations. For some plants, particularly trees, this problem can be solved by grafting from the successful product onto rootstock of some hardy species or variety, and then as long as propagation goes by grafting, the characteristics can be maintained. Reverting to propagation by seed would undermine this methodology, however.

Another drastic inefficiency in manual cross-breeding is that the desired genes may not be included with the offspring or with multiple offspring. Sexual mixing is a lottery, and sometimes the chromosome that has the gene that controls the desired characteristic is selected and sometimes not. With plant breeding, it is often fairly easy to grow hundreds of copies of one pairing, and then hope that at least one of them carries the desired characteristics. However, with plants that take years to get to production, the time needed to maintain all these possible copies is large and the investment large.

Perhaps one of the first steps in the genetic grand transformation on planets which have largely finished their industrial grand transformation would be to make the breeding of plants and animals more efficient. One step, even before the genetic map of a species was known and translated into characteristics, would be to make the combination process more efficient. A species with, say, eight pairs of chromosomes, would have two to the sixteenth possible combinations from two chosen parents. This is about 65 thousand combinations, which is much too large for any reasonable field trials. However, it is not necessary. Simply splitting the pairs in each parent and combining them into four descendants allows for the selection of two traits, assuming they are not recessive. Then the same process can be used again and again. To save time, four groups of chromosomes could be used.

Thus, simple separation of chromosomes and their return to a state that allows a growing plant to be started would provide a quick step up in the speed of, and rate of return on genetic selection. Any alien civilization which had passed through the later stages of its industrial revolution, which includes automation of processes, would be able to produce machinery to automate this process.

Thus, the development of improved varieties seems to be likely to be the first major, civilization-wide, step in the genetic grand transformation. At this point in the common path forward of technology, and therefore of any alien civilization, as per technological determinism, the alien civilization will still be growing their own foodstuffs in ways still recognizable as related to evolved growth. Once chromosomal selection is common, the way is paved for two other advances: the interpretation of specific genes, which allows chromosomal selection to be made even more efficient, and the alteration of chromosomes to modify individual genes. This latter step is the one that is most tricky, but the former one, if done earlier than the latter one, will facilitate it and make it much quicker to bring to success. Gene interpretation is something that will fall into place reasonably quickly, if the alien world is like Earth in that there is great genetic similarity between different organisms.

Sunday, September 25, 2016

Life Around Hot Stars

This is not about really hot stars, the O’s and B’s and A’s as everyone knows that their lifetimes are too short to provide enough duration for life to originate and evolve. However, there seems to be a common misconception about F’s and G’s, and it affects the origination of life.

When you hear someone talking facetiously about life on Earth, they often say we have five billion years left before the sun turns into a red giant and engulfs the planet. Unfortunately, F’s and G’s vary their output a lot over their lifetimes, and that affects this number in two major ways. As an example of the variation, consider the sun, which has been modeled much more than any other star. The sun started out at zero power, but very quickly ramped up to about 70% of current output. From there to 100% of current output took about 4.5 billion years, and projections are that the output will go to about 200% of current output, after about another 5.5 billion years. This is when it leaves the main sequence and begins its evolution into a red giant, for the first time.

There is no need to worry about red giants such as the sun and other main sequence stars will become, as their lifetimes are much too short for a planet to originate life around them, even if the planet happened to be at the right orbital radius and had all the other correct conditions for life to originate. The red giant phase is followed by a collapse back to a much smaller phase, again moving the liquid water zone (LWZ) around.

The evolution of F’s and G’s appears to be fairly well understood, even if there is little data available. The changes all happen in the inner onion layers of these stars, being the hydrogen-burning core, the radiative transport layer, and the convective layer about that. The sizes of these layers change as the amount of unburned hydrogen changes, as it fuses into helium. These different sizes affect the output, and there is only one way it goes: hotter.

The liquid water zone starts in closer to the star, and moves out as the star grows hotter. The length of time a particular planetary radius stays within the LWZ might be thought of as the time during which life can evolve, and so it needs to be perhaps 4 to 5 billion years. This would be wrong. The LWZ is usually calculated as the bare rocky planet temperature, but atmospheres change this, if they possess greenhouse gases. Back when life was trying to evolve on Earth, 4 billion years ago, the Earth was not in the bare planet LWZ, but it was in the greenhouse LWZ. The planet would have been too cold for liquid water, if it had had, say, an atmosphere of pure nitrogen, which is not a greenhouse gas. However, back then the atmosphere had methane and carbon dioxide, and these raised the surface temperature, allowing liquid water to exist and the origination of life to begin.

The other end is less promising. As the output of a star increases, it will make the planet hotter, and this includes the atmosphere as well. A hotter atmosphere escapes more readily, so the devastation begins with the atmosphere becoming thinner and thinner as time progresses. Greenhouse gases make the temperature hotter on the surface, and as the star’s output increases, in order to keep the temperature in the liquid water range for as long as possible, it would be best to eliminate them, and go to an atmosphere with no greenhouse gases. Whether that can happen is uncertain, as it depends on what life exists. Carbon dioxide is produced by volcanic eruptions, photosynthesis, and fire or combustion of any sort of carbon-containing materials. It is a potent greenhouse gas, and only a small amount would be enough to shorten the time the planet dwells in the LWZ. Even if there are no greenhouse gases present in the atmosphere, the increased output of the star would be enough to move the bare planet LWZ out past the planetary orbit. For our own G2 star, we have about a half billion years left, which is not much compared to the five billion years that the sun will stay on the main sequence.

What this means is that our G2 star is pretty much near the top of the heap for stars that can originate life. A five billion year duration in the LWZ, aided by as much greenhouse gas effect as possible during the early cooler initiation of this period, means that if life, from the first membrane to a starship launch, takes four and a half billion, we just fit in. Maybe a G1 or G0 could also, with even less slack time. By the time a F9 is reached just about the G0, there may be none at all. So, for convenience in calculating the population of stars that could originate life, G’s and K’s are about the only good choices.

There are two numbers that could easily be calculated from this conclusion. One is the number of stars that might be have originated life all the way up to an alien civilization, no matter if it is still there or has left or gone extinct. Another is the number of stars that could originate life. They differ in the way they treat time. The second one is just the number of G and K stars in the galactic disk, which is about 11.5% by current counts of all stars in the disk, which is of the order of 10 billion. The result might be 1.1 billion, but that is too precise for the quality of data that is available, so 1 billion is a good rough estimate. The first one only looks at stars older than 4 or 5 billion years, which reduces the number by about half, if the rate of star-making has been approximately constant over the life of the Milky Way. In other words, about half of the G and K stars were formed in the last 5 billion years, and they haven’t had time yet to generate an alien civilization. This gets the number of stars that could potentially have hosted an alien civilization in the Milky Way down to a half billion.

Saturday, September 24, 2016

Life Around Cool Stars

Can life originate around a red dwarf? A few elementary observations have been pointed out already. There is a liquid water zone around red dwarfs, and if an Earth-sized planet were located within it, that would be a good start. An origin planet, one that originates life but not necessarily an alien civilization, has to have certain requirements. In one sense, a red dwarf is a easier home for life in that the lifetime of a red dwarf is immense, greater that the age of the universe, and therefore there is no bother about having to maintain the liquid water zone requirement with some combination of greenhouse gases during a long enough period to get life started. Earth’s star started out too cold for us, and Earth stayed warm enough due to a combination of planetary heat and greenhouse effects during the first part of its life. This isn’t necessary on a red dwarf’s planet.

If the opposite is the case, that planetary formation heat boots the planet out of the liquid water zone for the first billion or two years of its existence, it wouldn’t be a problem as the star-generated liquid water zone is going to be available for a lot longer than that. What is possibly a problem in this case is the amount of water that is going to be held onto in the atmosphere. If the heating is not too extreme, the usual mesosphere effect might limit the loss of water molecules into space, and when the planet cools enough to have condensed water, it might have enough for the necessary liquid ocean.

A different problem entirely is the other planet problem. If there are gas giants in the system, located at more distant orbits, they will affect the eccentricity of the target planet. With the ratio between the orbital periods high, the target planet will see almost the same gravitational pull over many of its orbits, and eccentricity can mount and the argument of periapsis (the direction of the furthest point of the orbit) can vary to exaggerate the effect. This means that eccentricity can get large, and then grow smaller again, and so on. How would this affect the origination of life?

This is a question of the rate of change of conditions on the planet and how that compares with what is needed to provide an environment for life to originate and evolve, first chemically and then biologically. Later, the question becomes a comparison of this rate of change of environmental conditions and the rate at which some primitive form of life might adapt to it, once life already has been originated and the question is whether it can survive for long. Perhaps the use of the term origin planet should not be devoted to planets where chemical evolution goes on for a while and then everything dissolves back into chaos, but only for planets where biological cells have come into existence.

Mercury is our hometown example of a planet whose eccentricity varies greatly, from zero up to 0.40, as a result of the gravitational influence of Jupiter and Saturn. The same type of planetary dynamics could affect a planet around a red dwarf. High levels of eccentricity denote extreme levels of seasonality on the planet. This does not cast it out of the liquid water zone, which is, possibly vaguely, defined as an orbital range where liquid water can exist during part of the orbit. Unless there was only a small amount of water on the planet, it should not all freeze during the short winter that such a planet would have. However, if life origination occurs as in the organic oceans theory, an ice cover would freeze the upper depths of the water ocean where the meniscus was and where the first membranes formed. Would that doom a continuation of chemical evolution?

If the organics froze at different temperatures than the water did, there might be disruptive motions at the surface which would certainly disrupt a membrane, held together only by intermolecular forces. So, here is an obstacle to life formation around a red dwarf star.

If there are no other planets, especially large ones, around this star, tidal effects would eliminate the eccentricity, circularizing the orbit, and so this extreme seasonality would not exist and the planet would not have this obstacle to the origination of life. The initial planetary heat obstacle is mitigated by the long lifetime of this class of star, but that raises its own problems. As the planet’s orbit becomes circularized, it is also likely to become phase-locked, such as our moon, at a 1:1 ratio of rotation period to orbital period, or like Mercury, at a 3:2 ratio. This slowing of rotation does not only affect the crust, but also the mantle and core. And when the core stops rotating, there is no magnetic dynamo effect to produce a magnetic shell to protect the planet’s surface from charged high-energy solar wind particles.

In this situation, there is only the atmosphere to absorb the high-energy particles, and the upper reaches of the atmosphere will be stripped. Over time the atmosphere would be thinned. Red dwarfs do not have either the quantity nor the temperature to produce as much solar wind as a G2 star, but they do produce some, and thus the numerical question needs to be asked: Can the atmosphere stay heavy enough for long enough to allow this planetary heating period to pass and still have sufficient atmosphere to let life originate and evolve? Solar wind might preferentially break up water molecules in the upper atmosphere into hydrogen and hydroxyl ions, and then the hydrogen would escape from the atmosphere, essentially depleting the water supply.

Climate on a phase-locked planet would be very different that what it is on a rapidly rotating one. With concentrated solar heating on one area, either permanently or for a good fraction of the planetary year, there would be strong convection winds generated. These winds should extend both to the surface and up into the troposphere in a toroidal fashion, although topography, if it exists, might disrupt this. Strong persistent winds over an ocean surface creates great waves, and if an organic ocean existed above a liquid ocean, it might be totally broken up by waves which were deep enough to involve both the upper organic layer and the lower deep water layer. This would mean no meniscus and no origination of life, by the theory used here. There might be some craters where wind played a lesser role and origination could take place. Remember, however, that evolution, both chemical and biological, is proportional to the numbers of potential candidates for mutation, and if only a crater of them existed, life origination might need tens of billions of years instead of only a couple of billion.

This would mean that even though red dwarfs, formed near the beginning of the Milky Way, might be in the process of originating life in a crater on some phase-locked planet in the liquid water zone, the atmosphere might be lost before the process completed. Life origination involves a complex system of very diverse elements, and figuring out just how it might happen around a red dwarf star, when we have only Earth as an example, is extremely taxing mentally.

Thursday, September 22, 2016

Where are the Black Holes Hiding?

Black holes were thought to have been ruled out as candidates for the dark matter present in the galaxy by the use of some interesting techniques for searching for them, such as micro-lensing. This means looking for the bending of light rays from distant sources as they pass such an object. There were none found in the multiple searches.

The searches were concentrated on the supposed location of the dark matter, which was in a halo around the Milky Way. Some measurements of the velocity of stars around the center of the galaxy were use to estimate the total mass of the galaxy and its distribution with distance; in other words, how much is in the disk and how much in the bulge and how much in the halo. Unfortunately, the measurements made indicated that the dark matter was in the halo, so that’s where the searches were conducted. Exactly why there are so few black holes in the halo should be an interesting topic for another time.

Recent results on the velocity of the stars around the center of galaxies in general, not just ours, showed that the velocity curves are proportional to the visible mass. This means that the invisible mass is proportional, in location and amount, to the visible mass. Measurements of distant galaxies can not be three-dimensional, but two-dimensional, so to be precise, the invisible mass is proportional, in distance from the center of the galaxy and the amount, to the visible mass.

The post on black holes being prevalent in the galactic disk of the Milky Way, and by inference, in other galaxies with disks, seems to have been prescient, as they serve to explain this result. Black holes, and their less-massive cousins, neutron stars, are mostly invisible to ordinary astronomical observations. A search for them using gravitational lensing, concentrating on the disk of our galaxy, would help in confirming their prevalence and their contribution to the missing mass. Where should they be searched for?

Black holes form from large stars which undergo supernova explosions, leaving a large part of their mass behind. At this time in our galaxy, large stars occupy the entire disk, meaning the entire vertical column as well. This is because they form from large clouds of gas, which have that vertical distribution. While the large stars are alive and illuminating, they should follow the same distribution. However, because they are more massive than smaller stars, interacting with these smaller stars will change the vertical distribution, much like heavier molecules and multimolecular particles drift downward in the mesosphere. This, of course, is fortunate for life on Earth, as it reduces the loss of water into space from the atmosphere, and helps keep enough here for us to fill our pools.

As a black hole ages, it interacts more and more with other objects in the disk, and since a large majority of them are smaller stars, it will exchange energy, both kinetic and vertical potential energy. This might be thought of as a kind of equipartition of energy, and has the result that the black holes drift downward over time toward the medial plane of the galaxy. Now, the medial plane of the galaxy is not necessarily a plane, but a curved surface, as interaction with dwarf galaxies in orbit around the Milky Way distort it. Yet, the basic idea holds, in that black holes should over time form a tighter distribution than their original large stars, or smaller stars. This is where they should be searched for.

The distribution of black holes is nowhere near as dense as, for example, in a swarm of them that might comprise the central mass object in the galaxy. Yet black holes in a swarm do not interact and do not collide, as their numerical densities are too low and their interaction cross-sections too small. We see no large gamma ray bursts from the center of the galaxy that would be the indicators of black hole collisions. Nor do we even see any binary black holes spiraling in to self-destruction, such as might be formed by a close encounter between black holes in such a swarm. So it is even less likely that there would be any such signature of a high population of black holes in the disk, even in the thinner disk occupied by older black holes. In other words, black holes are innocuous neighbors. In order to account for the missing mass in a galaxy, there might have to be more mass in black holes and neutron stars than in visible stars, but this still would not provide any obvious signatures. Younger galaxies should have less of a black hole count in their disks, and older ones more, and this is something that could be examined, if someone could figure out how to detect black holes in the disks of distant galaxies.

Galactic perils that might face an alien civilization include stellar encounters, where the approach of one star toward the solar system of another might disturb planetary orbits. The extreme case of this is where they strip the solar system of one or more planets, but the less extreme case can be just as disturbing to an alien civilization. If the stellar encounter results in the change of a planetary orbit, even one of the outermost, over time that change will have an effect on the orbit of the planet upon which they reside, perhaps moving it out of the liquid water zone, making it more eccentric, or causing some other perturbation of orbital or planetary parameters. This would require the alien civilization to respond, if they desired to preserve their civilization.

The rate at which solar systems are disrupted by stellar encounters in the Milky Way, especially in the further out spirals, is not large, and if it were increased by an order of magnitude, to account for large numbers of massive black holes and neutron stars, it would still not eliminate the possibility of alien civilizations. It does imply that they have another interesting observational challenge. It is very simple to measure the proper motion of all the stars in our vicinity, so we can see which ones will come close and when the point of closest approach would be. As noted elsewhere, this might be a peril for the alien civilization but it could also be an opportunity, in that interstellar travel would never be easier than when another solar system flies by the point of closest approach. But in the case of black holes and neutron stars, the location of them is not easy, nor would be the determination of their proper motion and thereby the point and time of closest approach. Alien civilizations would have to figure out astronomical equipment able to perform this search and measurement, if they were to properly plan for their long-term future. On Earth, we haven’t really put much attention into this, but perhaps, once the realization of the prevalence of black holes in the galactic disk sinks in, we will.

Sunday, September 18, 2016

Where Are All the Black Holes?

In a previous post it was noted that there seems to be a lot of undiscovered black holes around. If you go back and figure out how many O and heavier B class stars there were, all of which produce black holes when they die, it turns out there should be numbers comparable with the number of stars in the galaxy. Is it remotely possible that the Milky Way is holding, say, ten billion black holes with masses ten or more times that of the sun?

Everyone seems to already know about the discovery of missing mass in galaxies, and how stars out in the disk are rotating faster than they should, if all the mass in the galaxy was in visible stars. They act as if something else is pulling on them gravitationally, but no matter how carefully stars are counted up, they don’t match what is needed. So the problem of missing mass came up and has been around for the most part of a century. No solution yet.

Having ten billion black holes with ten solar masses each would be a good start toward filling that gap, but there doesn’t seem to be any way to see most of these. A few have been noticed because they are binary with something else, and that makes some X-rays or some gravitational waves, and these are detectable and traced to being a likely black hole. But, is it possible that such a huge number of them might be present here in our own galaxy?

Throwing in another ten percent of the current population of stars isn’t going to change the fact that stars in the disk are widely separated and don’t have close encounters very frequently. If the black hole population is distributed like the stellar population, and why wouldn’t it be, the black holes are just spread out here and there doing nothing at all, not emitting any radiation or interacting with anything. They are too small to occlude anything. They likely blew away their planets when they went supernova to form the black hole. If they did have planets, in anything but very close in orbits, no one would notice as they do not radiate. The planets would have cooled down from whatever heating the supernova explosion gave them.

In a phrase, they are very quiet and tidy neighbors. What difference would it make to an alien civilization to realize that there were many black holes spread all over the galaxy? Sending out an interstellar probe to another star would mean there is a chance of the probe passing near an undetected black hole and being deflected, but the chance of this happening is negligible.

A black hole would make a fine target for a gravitational slingshot velocity assist, except that all the stars, and presumably black holes, in the vicinity are going around the same speed in orbit around the galactic center. This velocity is nowhere near fractional light speed, even if there was some geometry that could take advantage of it. So, velocity augmentation is likely a dead end.

If there was some gas around it, and it were possible to put a satellite there and direct some of the gas into the event horizon, there would be a source of X-rays. What could an alien civilization do with this? A galactic equivalent of a GPS satellite system? Granted that black holes are small, there might be a bit more precision available from this than with simple star-tracking, but stellar navigation is likely to be excellent using only star locations. Once measurements are made of all the proper motion of the largest and brightest stars in a neighborhood, traveling around that area can be done with elementary sighting apparatus.

Communication would not be a good idea, either, as the information carried by a system like this would be so small as to be useless. Material deposited on one side of a black hole would be only visible from receivers in that direction, so the idea of a beacon with signaling doesn’t work either. In short, there doesn’t seem to be any benefit that an alien civilization would have for discovering a black hole near them, and perhaps going out to it and establishing an orbiting station there, any more than there would be if they did this around some O class star with no planets.

One possible exception comes from the fact that about half the stars in the galaxy are binaries or higher multiples, and therefore it might be that significant numbers of black hole binaries exist. Black hole binaries have been successfully modeled, and it turns out they generate huge amounts of energy as the binary black holes come closer after having lost angular momentum and energy to gravitational waves. We just barely know how to detect gravitational waves, but could an alien civilization be able to develop some unimaginable-to-us apparatus to absorb the energy of the two black holes, for a few million years as they grow slowly closer together?

Everyone talks about how fusion energy is the source of everything in the universe, as it is the source of energy for every star that exists. While this is true, it is also true that gravitational attraction is what makes fusion energy generation possible, and the amount of gravitational energy in a binary black hole is so much more than the energy an alien civilization needs to operate that, if there is any way to tap it, it would provide the energy source they need. If fusion fails, does going out twenty light years to the nearest black hole binary and capturing its energy make even the slightest amount of sense? Is there any way this amount of energy could be beamed back to the home planet, to avoid the difficulties involved with capturing it, converting it, storing it in some materials, shipping the materials through immense distances, and then doing the opposite to make it available? If beaming were possible over a distance like twenty light years, this would eliminate the delays involved in moving matter around in the galaxy.

So, for now, a substantial black hole population appears to be useless, with some very remote chance that a power source could be developed from them. This clearly appears to be a very interesting topic to delve into.

Saturday, September 17, 2016

Swarms of Black Holes

Black holes are almost the worst thing to try to observe, as they intrinsically give off no radiation at all. No particles and no photons. Nothing to see. The only way they are noticed is when they disturb something else, like a planet, a cloud, a star, another black hole, and either disrupt it, merge with it, or fling it somewhere where it can be noticed.

This being the case, exactly how would someone distinguish between a large black hole, if such things exist, and a cluster or swarm of smaller ones? One justification for this being a reasonable question, physics-wise, is that black holes are really, really small. They are the size of neutron stars, or small planets. If you have a bunch of them, how do they ever find each other in order to merge with one another to make a giant black hole? The collision cross-section is so small they would just fly around for longer than the age of the universe and the age of the next universe and lots longer than that, provided they had some kinetic energy of the order of the stars that formed them.

Maybe you might imagine that they grow by collecting gas. What happens to the gas nearby when a bit of it falls into the black hole? Out of the envelope of the black hole comes radiation, particulate and photonic, connected to the absorption process, just like a solar wind. So, the gas blows away, and what is left to fall into the black hole? There is also something called angular momentum that keeps the dust from falling inward, just as with a planetary disk and the galactic disk. It makes the gas spin around the black hole. So, building up a massive black hole with millions of solar masses is a difficult process.

How about swarms of black holes? Small black holes get made in the supernova process all the time. A star with a mass greater than about ten solar masses is going to collapse inwards after it uses up its hydrogen and then helium and then other elements in the fusion process, and suddenly there is no heat being generated inside to maintain the internal pressure. Collapse, and you have a neutron star, which finally gets big enough to generate a space-time envelope capturing all photons and matter inside it. A black hole. There should be lots and lots of these. Large stars, maybe about .05% of the total population, can undergo this transformation, and they only live twenty million years or so. If they are .05% now, and they live 1/500th of the age of the galaxy, there should have been 25% of the current stellar population passing through the black hole transition over the life of the galaxy. That is one lot of black holes.

Even if this number is crazy large, and there is only 10 billion black holes around, that is still a lot. The number of stars in the galaxy is 200 billion or so, and it is hard to figure out how instead of 25% of this there is only 5%, but even if the number of black hole survivors is 10 billion, and they are all around us, it is not hard to see why these heavier objects would not preferentially drift into the center of the bulge and make a swarm. They are so small that a swarm of a million would not produce any visible dual black hole collisions in the history of mankind. The swarm might be concentrated into a tenth of a light year, and perhaps could have excluded other objects, such as heavy stars created nearby and which drifted into the center, by the radiation pressure caused by various absorption events. A heavy star has a huge cross-section, compared to a black hole, and would have received much more momentum after an event than another black hole. Compare the size of Rigel with that of Earth, if you want a picture of this.

Why wouldn’t such a swarm of black holes be detectable by gravitational wave detectors? Huge masses flying around in the gravitational field of the swarm should make some disturbances. After all, the curvature of space-time is at its extreme around a black hole, meaning that there is a spreading disturbance outward from it. The difficulty with this is the wavelength. A black hole traveling across the swarm, a distance of a couple of tenths of a light year, for example, might take a hundred years, meaning the signal is of the order of a billionth of a hertz. Perhaps it interacts with other black holes on the way across and generates signals only a thousandth of a hertz. This is simply not within our detection capability unless we wait centuries. Gravitational wave detectors are good for quick events, like black hole collisions or mergers with stars, or something else fast. What makes things even worse is that the signals from the motion of individual black holes in a swarm are counteracted by the signals from motion of others, so the amplitude of the signal is very low as well. So, detecting a swarm of black holes in the center of the galaxy as opposed to a single massive black hole is probably not going to happen.

Possibly it will be within equipment capabilities to determine the difference between these two scenarios by some other means. It isn’t clear how gas being absorbed by a ten solar mass black hole would give off different radiation in detectable bands that gas being absorbed by a million solar mass black hole, but perhaps there would be some differences. It also isn’t clear how the residual gas surrounding the black hole would be different if it was being cleared by a million solar mass black hole as opposed to being cleared by a hundred thousand individual black holes of ten solar masses each. Perhaps there would be more turbulence if the clearing was being done by a swarm of rapidly moving black holes as opposed to one stationary one in the center. Perhaps the total distance cleared would be more, being the total of the smaller clearing distance plus the mean dispersion radius of the black hole swarm as opposed to the larger clearing distance of the supermassive black hole. Some more complicated computations are necessary.

The implications of this for alien civilization are not clear at all. Would an alien civilization arise in the bulge somewhat near the swarm, or would an alien civilization ever conceive of a reason to travel near to the swarm? Is there any mechanism by which they could extract energy from such a maelstrom? Not obvious at all.

Wednesday, September 14, 2016

Too Far Planets

Suppose we consider as a thought example a planet which was the first to develop intelligent life which ran out of resouces and wanted to preserve its civilization on a planet similar to its own. This type of planet is what we call alpha-habitable, and means a planet with animals and oxygen and soil and plants, one which is just great for colonization and one which is what all science fiction writers envision when they write those great stories about interstellar voyaging.

Unfortunately, it seems they are not all that common in the galaxy. Suppose in our example there is just one alpha-habitable planet in the whole galaxy at the time the first alien civilization starts searching. It is likely on the galactic disk, and an average distance might be thirty-five thousand light years. Suppose the alien civilization is highly motivated to get to this planet. How might they attempt it?

When we on Earth scan the skies for future Earths, we do not look out this distance. Instead, we look out a hundred light years or so. If we think about going there at a fractional iight speed, one percent or ten percent come to mind. This means a trip of a thousand to ten thousand years. An immense time for us, as we only have recorded civilization for a few millennia. If you ask an engineer about constructing something which would last longer than the Roman Empire, in space, with no failures significant enough to doom the voyage, you should expect ridicule. We simply have no experience with this length of time. Stone monuments might last this long, but nothing with moving parts.

An alien civilization, such as in our example, might last a million years before it needed to colonize a new solar system. If you asked an engineer in that civilization about something that had to last a thousand years without significant failures, he might point out some examples. He might refer to textbooks written five hundred thousand years before about building in reliability. This type of trip doesn't appear as ridiculous to the alien civilization's engineer as it does to ours. So, if they were lucky enough to have an alpha-habitable planet located only a hundred light years away, they would certainly think they could get there.

But a planet thirty five thousand light years is another challenge. At the range of speeds likely, this means three hundred and fifty thousand years up to three and a half million years. Now that the travel time approaches or exceeds the maximum duration of the civilization, the question has shifted from the eminently possible to the outlandish and absurd.

Reliability is not the only factor that seems impossible. What about providing enough energy to supply the ship for the length of the trip? There would be no propulsion power needed, as the ship would use the initial part of its propellant coming up to speed and preserve the rest until it was necessary to decelerate upon the approach to the destination planet. It is the hotel load, the power needed to keep the systems in the ship running for that length of time. Perhaps all that is needed is a clock with a switch to turn the systems of the ship back on once the neighborhood of the destination was reached.

What powers the clock? What source of energy can survive tens or hundreds of thousands of years of being radiated in the interstellar void? Nothing chemical would work, as these systems have a shelf life and shelf life is not denominated in units of this size. A nuclear reactor, a bit overpowering for a clock, would suffer from decay as well as the effects of the interstellar radiation. A bank of fuel cells would suffer from erosion for the electrodes, as well as ablation of other components. A radioactive source is going to be irradiated as well, even if something with a very long lifetime was chosen and properly sized.

Robotic solutions simply don't work and so the inevitable conclusion is that something biological is needed. Biological systems are self-repairing, and seem to offer the option of having a reliability higher than robotic systems, but with quite different requirements and design. This alternative might solve the reliability problem, but it is for us a complete unknown.

The energy problem might be solved if there were intermediate stops where energy sources could be tapped. This prevents extreme problems. To have a one-stop trip, instead of a non-stop, the propellant to slow down and stop the ship has to be carried, and also the propellant to re-accelerate the ship. And we all know about the accumulation of mass aboard a rocket ship. Mass does not go up linearly, but because it is necessary to initially accelerate all the fuel on board, even more is needed. Many times the original fuel is needed for a one-stop trip. For a multi-stop trip, the numbers become insane.

What about picking up fuel at each stop? If this was possible, it would relieve the ship of the necessity of carrying multiple times as much fuel as minimally necessary for a non-stop trip. Still, the energy necessary to power that propellant, even if it were scooped up at each stop, is necessary. A huge amount of energy required becomes even more huge.

What about finding stops where the energy needed could be obtained? There are no fueling stations on random planets in the galaxy. Somehow the materials needed to re-constitute the ship’s fuel would have to be gathered, and the various pieces of equipment necessary to turn these materials into fuel have to be carried and maintained for the entire trip, except for the portion from the last fueling stop to the final destination. If something like antimatter was used to keep the weight of the energy system down as low as possible, now, with a fueling stop it is necessary to carry all the equipment needed to convert whatever energy source is available on some planet back into antimatter. Since conversion is not likely to be anything like 100% efficient, even more fuel materials must be collected.

It seems that going this distance is simply beyond the bounds of possibilities. Some planets are simply too far out for even an aspiring civilization to attempt. If, as in our example, there is only one planet and it is that far, they simply must descend to sustainable life, or perhaps make the decision to no longer continue their civilization.

Perhaps a guess toward how far out too far out is would be a thousand light years. A hundred light years would be doable for an advanced alien civilization in possession of sufficient resources and somewhat beyond that as well. This has implications for how fast the galaxy would become occupied, and how fast the existing number of alpha-habitable planets would be exhausted.

Tuesday, September 13, 2016

The Window of Colonization

If an alien civilization wants to do colonization, there is really no substitute for an alpha-habitable world. This has all the things already completed that are necessary for the alien civilization to simply move in and get started resurrecting its culture from scratch. Alpha-habitable means life has started there, and that presumes that the planet is not in the throes of basaltic flooding, or suffering from intense planetesimal bombardment, or has intense stellar radiation cleansing the surface of life. It means the atmosphere is okay. It means gravity is in the right range, and planetary parameters are just fine. The star type is right. Everything is there, except for the aliens. It is like a planet with a red carpet laid out for respected guests to arrive.

But, like any esteemed establishment, you have to get there at the right time. There is a window of opportunity. Getting an idea of how broad that is can be done by examining the progress of life on Earth, our only example.

The planet formed about four gigayears ago, and the first bacterial fossils that can be confirmed come from about three gigayears ago. Some time before that life originated, perhaps first chemical life and then biological life. Part of this gigayear was devoted to the evolution of the first biological cells, and an earlier part was devoted to the reformation of the planet by impact. Still, coming this early is not a good idea, as there is no oxygen before about two and a half gigayears ago. It took this long for photosynthesis to originate and evolve, and then become so prevalent and prolific that it could change the entire atmosphere. It would be possible to migrate after oxygen is established, but the whole land surface is just rocks with maybe some sand. Still not a hospitable planet to move to.

Cells keep evolving, and we get eukaryotes and multicellular creatures, but all in the oceans. There are animals in the oceans by 600 megayears back, and the first entry onto land starts about 450 megayears back. This was likely some fungus, and it needed to evolve a lot before living on land was common. Eventually it happened, and plants began spreading over the surface. There were the first animals, the predecessors of the dinosaurs, at about 300 megayears back. Insects were there by then as well.

Dinosaurs themselves arrive around 200 megayears ago, meaning there would be meat to eat, if the colonists wanted to do some hunting, and forests and jungles as well. Mammals would be present by 200 megayears ago, but only small ones. Sometime later birds arrive.

Earth may be a special case, as there was a major extinction event, one of many in its history, about 66 megayears ago, which is when the dinosaurs bid Earth goodbye. Since then, mammals have dominated the surface of the planet. On another planet, there might not be such an extinction event, such as might be caused by a major impact or a basaltic flood, meaning that mammals might have to out-evolve the dinosaurs, or perhaps simply continue to co-exist with them. Climate change was undoubtedly happening, as the Earth went through multiple ice ages separated by warm periods when there was no ice at all, even at the poles. This may have had an effect on the competition between mammals and dinosaurs.

We can now see how short a colonization window there is. From the dawn of the Earth, however you define it, maybe 4 gigayears ago, a colonist hopeful would have to wait at least until about 200 megayears ago, which is only five percent of its lifetime. The window closes about now, as within a few hundred more years, humans will possibly have developed their technology enough to have the planet pretty much sewn up. Whether or not an alien civilization would simply displace an existing intelligent species is something to be discussed further.

When we were comparing how many alpha-habitable worlds there are, little account was taken of the length of time in preparation there would be. Out of a thousand worlds that are destined to become alpha-habitable, most would still be in the earlier stages of change, so that they wouldn't be alpha-habitable at all at any snapshot in time. The numbers that are actually alpha-habitable, are less than five percent of the total.

On the other side, if the planet is alpha-habitable, how long does it stay that way? Perhaps life just goes on and on, waiting for some extraterrestial colonist ship to come its way, and it could last this way for a gigayear or more. On the other hand, each year that passes might mean that an animal species starts to use tools and communicate, the two hallmarks of beginning intelligence. It could very well be that instead of talking about the probability that an alpha-habitable planet develops intelligence, the mean time to develop intelligence after the emergence of mammals might be a better way to quantitize this. Perhaps half develop intelligence 200 megayears after mammals emerge, and three-quarters after 300 megayears, and seven-eighths by 400 megayears. This assumes there is no condition on most planets that prevents intelligence from appearing, and although this subject has not been thoroughly explored, none has appeared.

With this way of looking at things, a 200 megayear window is about all that an alien civilization could expect, and they could be unpleasantly surprised on some planets to find it happens after only 100 megayears. With a window this small, the number of alpha-habitable planets, without life, is much smaller, that previously estimated. Instead of a thousand, there might only be fifty or a hundred when the first alien civilization in the galaxy is about to start hunting for a colonization site.

During the million year reign of the alien civilization on its first colonized solar system, there might be one of the hundred or so alpha-habitables that begins the ascent to intelligence and a second alien civilization. Before it uses up the hundred, there might be a fifty percent chance this would happen. The second alien civilization would find almost no worlds for them to colonize, thanks to the first alien civilization's diligent efforts to vacuum the galaxy of potential sites.

While the numbers tossed around here can certainly be altered, it appears that the galaxy is home to former homes of great alien civilization, now inhabited by no one at all, or by a post-golden age civilization that relies on sustainable energy and materials. Few pristine planets for colonization present themselves and those that do would be scooped up early in the possible window for colonization.

If this is the situation, it provides a shifting ground for answering the original question of this blog, where are all the aliens. The answer might just be they are on their home solar systems, some being solo worlds where intelligent life originated and formed civilizations and others being ones which were colonized. All of them are out of resouces and are making due with what solar power they can utilize, along with non-scarce resources. None have the capability any more of doing any more colonization. In this picture, Earth escaped being colonized because its window of colonization opened too late for any nearby civilizations to take advantage of it.

Monday, September 12, 2016

The Milky Way Has Been Vacuumed

It's quite easy to write about colonization of one solar system by aliens from another solar system, but just how possible is it? This question has many aspects, such as how to build a starship to move from solar system to solar system, and would aliens be motivated to do it, and so on. But one which is quite important and has not received too much attention is this: would there be any available planets to colonize?

This question is exactly about how many potential planets there would be, and how many competing alien civilizations looking for one. If there are lots of civilizations and few potential planets, it means that no matter how good the starship design is, it isn't going to happen. That's what the vacuuming is all about. It seems likely there aren't going to be any planets to go to, in the large.

Let's toss some numbers on the table. Suppose there are about 10 to the eighth stars in the galaxy. Suppose about ten percent are in the disk, which is where life can originate, mostly. Suppose about ten percent of the stars are G class or K class, which is where life might originate. Higher classes burn out too early and lower classes are too weak. Suppose about ten percent of these G and K stars have a rocky planet in the liquid water zone, and about one percent of them have a planetesimal impact of the right kind to form the conditions for the origination life. Yes, we are sticking to the organic oceans theory for the origination of life. This means that there are about a thousand planets which originate life.

Let's assume that one of them is the first to give rise to an alien civilization. They live their life, figure out everything good about how to maintain their civilization, mine their whole solar system as far as is economical to do so, and eventually start running out of materials. Let's give them a million years, which is really stretching the limits of materials in one solar system as consumed by a robust alien civilization. They need to move elsewhere if they want to preserve their civilization, and for the purposes of this calculation, we assume they want to.

They use some big telescopes to monitor other planets, and find one, which we have called alpha-habitable, to go to. Alpha-habitable means it has life on it, and this is by far the best type of planet to colonize. They go there, and start all over again. But a million years later they are facing the same problem. So they move again. And again. After a thousand moves they have used up the alpha-habitable planets in the galaxy. If they took about four billion years to evolve to intelligent aliens, this means after another billion years, they have to go to planets that were formed later, and became alpha-habitable during the time they were running around colonizing the original ones. This only gives them about another hundred million years, and the third generation is only ten million, and soon they are at a point where there is simply nothing left.

They have vacuumed the galaxy for every alpha-habitable planet. They have no where to go. What are they going to do for the next five billion years?

While they were busy colonizing and living and exploring and such, some of the other alpha-habitable planets were busy evolving, and some of them would come up with alien civilizations as well. The first one in the galaxy was busy taking care of the alpha-habitable planets by themselves, but the second one, assuming they also think their civilization is worth preserving, is going to get into the running for finding and colonizing alpha-habitable planets. With two of them going at it, they have only a half billion years supply. Evolution doesn't stop on other planets as well. There is going to be a third, and a fourth, and a fifth, and so on. Now the supply of alpha-habitable planets is beginning to look pretty small and maybe they are exhausted as early as a hundred million years after the first colonization in the galaxy, or even sooner.

One of the first realizations in this blog was that all alien civilizations would develop the same technology, and it wouldn't be too long before they had done it all. This means that all the alien civilizations can build the same giant telescopes, and the same computers to analyze the data, and the same propulsion systems to drive a starship, and everything else. They are all facing the same fate and the same prospects. If they want to colonize, they are going to have to do something different.

What are the possibilities? One is to live on beta-habitable planets, which are planets without life, like Mars. Unpleasant, and perhaps impossible to do in a self-sustaining manner. We on Earth like to fantasize about having a Mars colony, but that would be done using resources from Earth. The idea that Mars inhabitants would obtain everything they need from Mars in order to survive for millennia without resupply from Earth has not been analyzed. We are exploring the planet, but we have not done an ore survey, or figured out how to operate in hermetically sealed caverns, or much else. It could be that too much energy is needed, as compared with how much could be obtained there. Or there could be some materials that simply aren't common there, but are necessary for modern technology. Some planets might be beta-habitable in the Milky Way, and alien civilizations would likely be able to find some, but then they have to make a choice about whether that kind of life is worth having.

Another choice is to try and become space nomads, and not bother to try and establish life on the surface or near-surface of any planets, but just to live in space and exploit planets for resources. This might be possible, or not, depending on energy and materials tradeoffs.

There is a simpler and clearer way to consider the original colonization idea. That is to compare the probability that an alpha-habitable planet develops an alien civilization with the ratio of the lifetime of the civilization on one solar system to the time between successive alpha-habitable planets arising. If half of the alpha-planets develop an alien civilization that wants to preserve itself by colonization, and the civilization expires on one solar system faster than a new alpha-habitable planet arises, it is out of luck. Once the initial supply is consumed, there is not enough generation to allow colonization to continue. This comparison of two key numbers may dominate what we observe in our galaxy as far as life goes.

Sunday, September 11, 2016

Aliens Arrive Today!

Are we ready for what might be tomorrow’s headlines about alien arrival here at Earth? To be prepared, we should understand as much as is possible about alien civilization, technology, motivation, and culture, and it doesn’t seem we are doing much in that direction. With such little preparation, things might go badly:

There wasn’t anywhere you could go that didn’t have the news blaring about the alien ship heading for Earth. It suppressed other topics that we used to think were essential to daily life, and rose to the top of the news on every media. An alien ship had been sighted just inside the moon’s orbit, heading toward Earth orbit. It was black in color, and not very warm, so it was hard to detect it, even worse than asteroids of the same size. In three days it would be in orbit, and then probably land shortly afterwards, and no one at all had figured out what to do. No government had an alien department and the United Nations did not either. No advisors or consultants specialized in what to say to these aliens when they arrived, or what to do otherwise. Military types were all about defense and weaponry and they seemed to be the only ones able to respond rapidly, but no one wanted to assume the aliens were malevolent. Military solutions were temporarily off the table. But that left a vacuum.

Someone had the bright idea of collecting together some leaders to have a meeting about what to do, so while the starship sped toward the Earth, a meeting was convened. Speeches were made, and the group came to a reluctant consensus. They needed a spokesman for Earth. Someone had to represent us. Since all the people at the meeting were representatives of some nation or another, it wasn’t likely they would think of anything else, but at least it was a consensus. News people took polls, and the more sane suggestions involved the same thing. Somebody needed to talk to them. The obvious choice was a mild-mannered fellow from a small country who was currently President of the United Nations General Assembly. There were lots of objections to this choice, but there were more objections to anyone else. By the time the starship had entered a polar orbit, he had accepted the role and was ready for the task.

Some others with a bit more foresight had gathered together all the experts on exotic languages into one hall, and even figured out how to have them communicate to one another and to someone else on a telephone line. They huddled together, and were engaged in non-stop discussion of how to approach an alien language, when the starship opened up a commonly used radio channel and said: “Hi”.

At least it was English. The President of the UN was rapidly connected and began his speech, which began by introducing himself and wishing for peace and welcoming the aliens to Earth. It was a nice speech and everyone down here thought he did a fine job as spokesman for the planet. The starship said, “Thanks”. It was clear that there would be no language problems, and the UN President decided to get friendlier and state that he and we all were pleased that the aliens knew one of our languages. There was a bit of a pause, and the starship said that it had been listening to us for about twenty years already, so it knew plenty of our languages, and chose English because it was most common. At this point, Earth people were all relaxing, as they had all been listening to the conversation, almost every single one of them. Now it sounded like the aliens were good guys.

It was time for the spokesman for Earth to step up to bat. He asked them if it was possible to have a meeting between them and us, after a bit of a monologue about that was how we did things. Of course, mostly everybody on Earth had figured out that any aliens who had been listening to us for twenty years would know this, and the President did too, but he had to say it. The alien ship just said, “Sure. Come on up when you’re ready.”

Apparently the aliens had missed the fact that only a small number of people were trained to travel up to low earth orbit, and the UN President was not one of them. They must be able to notice the International Space Station, however, and note it was pretty small and not many transport rockets were heading up to it. The pause after the alien response must have been noticed quickly, because the alien voice added, ‘I don’t have a lander.”

Humans started wondering what kind of low-class alien starship didn’t come with a lander. It seemed like not having a dinghy on a yacht. The UN President hadn’t even considered this possibility, and none of his advisors had either, so he simply temporized and said he would get back to the aliens about that. The alien talking to them was obviously pretty astute, as he figured out the problem right away, and tried to make it easier on us by saying that somebody already up here could fill in if they wanted.

There were four guys on the ISS at the time, and they were pilots and scientists, not a diplomat among them. This was obviously not a great solution, but what else was there? Some NASA people called the President to explain that they didn’t have any way to get over to the alien ship, which was about ten kilometers higher in orbit and in polar orbit as well, meaning a velocity change of thousands of kilometers an hour would be required. What was left? Invite the alien spokesman over to the ISS? Not a great place to visit.

The idea of meeting the aliens died that quickly. It was replaced by the idea of having conversations with the aliens, which is what they would have had anyway if the alien ship had landed on Earth and met with the UN President and his team. So the President’s team quickly, in a matter of twenty minutes, figured out some questions to ask. The President got back on the radio, and the alien voice was still there. It was probably obvious that there wasn’t going to be any meeting, no matter how historic it would have been. Maybe if they had three months to get someone trained both in traveling up to orbit and in diplomacy, it would work. So the first question, probably a bad choice, was about how long the aliens were going to stay here. They said they would be in orbit about ten days. It was so incredibly reassuring to the President’s team, and all the rest of humanity listening in, that the aliens didn’t seem to mind answering questions, and they were pretty clear with their answers. Perhaps human politicians could learn something from them.

Before the human team could ask the really important first question, the alien voice asked for some cheese. Cheddar would be the best, it said, but gouda or swiss would be great as substitutes. This was not what anyone was expecting. There was no video connection to the starship, but if there was, a totally vacant look would be what they saw. The President said that they would work on it, and the alien voice said: “Thanks, gotta go now” and turned off the transmitter.

As luck would have it, there was a rocket ready to go, and the world just kind of decided to replace the satellite payload with thirty kilos of cheddar cheese and send it up to the alien ship. There were several hundred reasons generated why the alien ship would want it, and even more learned discourses on cheddar cheese and its interstellar appeal were posted that anyone would have believed possible. The aliens didn’t open up their channel again, and the UN team of advisors came to the conclusion that the ship was simply waiting for the cheese, which was figured out to be a sign of good intentions, or something like that. Everyone did realize that a spaceship wouldn’t travel for tens of light years or more just for some cheese, no matter how good it was, so humanity was, as a whole, perplexed. They did launch the cheese rocket in two days, however, even without any further communications with the alien ship. It matched orbit as planned, and the ship maneuvered to the cheese satellite, and opened a hatch and dragged it in with some sort of long claw.

Four days later, the starship seemed to be breaking apart. Pieces the size of rocks were coming from it in the direction of Earth and entering the atmosphere. Radio communications were incessantly tried, and finally the alien channel turned on. “Hi” it said. Instead of the important questions that were on the President’s list, he had been advised to ask if the ship was all right. The alien did answer right away, saying “Sure.” Then the President asked if it would be permissible to ask some questions, and the alien ship did say, “Sure, but I only have ten minutes.” So the President started by asking the where the starship had come from, and the alien responded by explaining that he had been mining some asteroids for a while, and before that had come from a solar system in the direction of Centaurus. Why the alien ship had come to Earth was the next question, and that was answered in the alien’s first compliment. “Because Earth is such an excellent planet.” The next question was rather self-serving, but given the limit of ten minutes, the President asked if the aliens could share their technology with humans. Maybe he thought the cheese would be worth it, or maybe he just was expressing the hope of mankind that aliens would give them a free technology short-cut. The answer was apologetic, “Sorry, but I didn’t bring any of that stuff. I’m not going to build anything out here.” Larger pieces fell from the ship and finally the remaining part nose-dived into the atmosphere. It was just about ten minutes.

Humanity never did get to figure out exactly what solar system the alien was referring to, or what it had been mining, or why Earth was excellent, but they did guess that the cheese was for growing microbes, just before the toxins got rid of them.

Friday, September 9, 2016

Post-Scarcity Alien Civilizations

The process by which an alien civilization approaches scarcity can be quite diverse. The aliens could tap all the resources of their solar system. They could reduce their population, early in the history of their civilization, and postpone the onset of scarcity problems, perhaps out to a million years. They would adopt re-cycling techniques and perfect them, changing their mode of living to accommodate them. They would use their scientific knowledge for substitution of materials, minimizing the impact of the first to become scarce ones. But after all that is done, the inevitable scarcity of materials final hits.

One choice is simply to allow the civilization to become extinct. What was once a civilization at the peak of culture, understanding the universe, providing well for its members, becomes zero. Their philosophical understanding may make this an acceptable solution. Another choice is to save enough materials to perform a star flight to the nearest inhabitable world, and start all over again. The population could not move, but the culture could, and the starship could transport the knowledge and the DNA coding from their home planet to the new home planet. This still leaves the question of what the members of the civilization could do once scarcity had become so serious that the civilization could not be sustained.

Energy use per capita is one hallmark of an advanced civilization. Fusion plants seem to be the only way to raise this ratio up high and keep it up for millennia and millennia. But fusion plants, no matter how cleverly engineered, need materials, and sooner or later some critical material is going to be unavailable. Seawater extraction can provide some materials, but not all, and presumably, one of the critical materials for a fusion plant is going to run out. If their uranium and thorium resources have not been used up yet, fission power might provide a substitute for another long period, but this will also come to an end. Someday, the lights go out.

This day will probably have been predicted a huge time in advance, and so the alien society would have thought through their response to it. One response is to cease making aliens, i.e. voluntary extinction. But another is to return to relying on their sun’s power, as captured on the planet by photosynthesis, wind and water circulation. Living with a much lower level of energy per capita would be forced upon them. Likewise, materials would be short, and some would be too difficult to obtain under these circumstances. They would have an inventory list of what is available, and what is not.

One large question would be how much science could they preserve. Would there be electricity, coming from some hydroelectric source or some other source ultimately arising from solar flux? Would there be enough metal to make the generators and power lines? Initially, this might be the situation, and then a reduced standard of living could be obtained for some residual population. The lower their choice of population numbers, the longer this intermediate stage could prevail.

Long ago, during the initial phases of the civilization, they would have mastered robotics and genetics, and these would have changed their civilization thoroughly. Robotics would appear to have a higher requirement for materials, and might be lost first, but would it be possible to maintain the genetic transformations and inventions from the past under a reduced-power and limited-materials situation?

Genetics requires some equipment able to read DNA code and to modify it, as well as to gestate organisms. Gestation might be arranged for biologically, but reading DNA code seems to be implacable in its demand for computation. Can high levels of computation be arranged for using only materials which would last the lifetime of the star? We are still beginning to explore this area, so the answer eludes us, but if they could, then they might be able to lose only one of the two revolutionary pillars of their advanced society, robotics, and still rely upon genetics to accomplish whatever was possible with it.

This question lies at the heart of their status. Would they be able to maintain the genetic constitution of their species, or would it descend over millennia to some lower level, whatever level was maintainable using more elementary processes? If genetic manipulation could be maintained, then they could at the least, keep their species near the optimum in all the attributes they chose, such as health, strength, longevity, intelligence, and anything else on their list.

Hand in hand with this would be the maintenance of the creatures and organisms that they had designed for their civilization, such as intellos to perform the work of the society, biological factories to produce many items for their civilization, and means of generating both nutrition and fuel.

This choice, genetics or no genetics, might control whether they could continue to live in large cities. The arcologies that probably would exist at the highest state of their civilization might not be maintainable, without many of the needed resources, but still population could live in cities rather than be forced to be dispersed over the landscape in agricultural occupations. With genetics, they might still continue to make biological organisms able to extract some materials from the oceans or even other sources, ameliorating the scarcity that demolished the earlier level of civilization.

The lifetime of these reduced-level civilizations might be much longer than that of the higher-level ones. One estimate of the possible duration of a higher-level civilization was a million years, if everything was done to prolong it. With reduced-level civilizations, it might be tens or hundreds of times as long. If this is the case, it means that any star-traveler is likely to find civilizations in this situation, rather than the higher-level ones. The ratio might be a hundred to one.

If the Milky Way is able to originate life on many planets, and there are no obstacles permanently blocking the life from eventually evolving and developing into civilizations, this might be the predominant scene on a solo world, an alien civilization with an incredible history but a somewhat commonplace present. If that is the situation, all the easy options for colonization might be taken.

Wednesday, September 7, 2016

Clones of Earth

If there was a planet identical to Earth somewhere out in the galaxy, how similar would life on it have to be? This is simply a thought experiment, so we can assume identical is totally identical. The match does not simply cover the conditions on the planet, but the star that it orbits and other planets as well. Let’s throw in identical experience in the galaxy, such as a lack of nearby supernovas, and the same cosmic ray field.

In this example, Earth gets the same impact from a planetesimal that formed at a Lagrangian point in its own orbit, creating the organic oceans that are necessary for the similarly-named theory of origination of life. Its atmosphere is the same after the impact. In short, everything is the same. Now, life originates here the same way as it supposedly did on our Earth, but what happens after that? This is the simplest test for interstellar convergence, which is a hypothesis that says that evolution proceeds to the optimum in most situations, resulting in similar creatures on similar planets.

Similar creatures do not mean similar in every chemical detail, but similar in function and appearance. At the very least, enantiomers could be different on two different clone Earths. It is also not at all clear how enantiomers divide themselves into groups. Clearly two different molecules which interact would have to be of the proper orientation, so a right-hand version of one could fit against a left-hand version of another, for example; enantiomers which don’t interact could be completely random and all mixed between orientations. Furthermore, the coding for different amino acids could be different, and entirely unrelated to one another. These two variations would not affect either functionality or appearance, but would prevent hybridization between the two clone Earths, no matter how similar evolution worked out.

The question to be asked is: how might evolution not result in the optimum choice for each mutation? Two effects which tend to make optimal choices happen are the large number of possible mutators, being a large number of organisms, either simple, single-celled animals or eukaryotes. If there are huge numbers of them, one of them is going to get the mutation which leads to the next optimum condition, and eventually compete its way to being the dominant and then the sole version of the gene in existence, at least in that type of organism. The other effect is that of time. So many generations of any organism exist that sooner or later the mutation leading to the next simple step up, the optimal one, will be started. Again, after enough time for competition to winnow out the winners, the organism with the best choice of that particular gene emerges.

This process does not come to fruition in the situation where there are two or more genetic changes happening nearly simultaneously. If a non-optimal, but better than the original, mutation happens and begins to multiple, displacing the original version, and then another mutation happens which provides much more improvement in overall fitness, the competition for the first mutation is overwhelmed by the competition for the second. If a third one comes by, also offering a larger improvement, it would also delay any results for the first one. When these big changes are over, if they propagate throughout the numbers of that type of organism, the weaker improvement for the first change might resume, unless for some reason the competition is no longer valid. The one or two large changes have rendered the original change moot, and it no longer has any fitness advantage. If this happened on one clone Earth, and did not happen on another clone Earth, the evolutionary sequence would be different. This change might affect some later stages, as a different mutation might be possible for one sequence and not for another. This means the two planets lifeforms, the bios as we have called it, starts to diverge in a small way. Conceivably, this could happen multiple times or the downstream effect of a few such events might have large consequences.

The mechanism by which genetic divergence is clear. One change happens and before it can become optimal, meaning a suboptimal mutation occurs and disperses, other changes happen which prevent any competition on this locked-in one from occurring. After they concluded, the optimal mutation could arise, but it would not succeed in the fitness competition. The later mutation, which would have liked to take advantage of the optimal form of the first mutation, cannot be expected to occur unless the very rare possibility of a double mutation happens. Since mutations are unlikely occurrences, having two coordinated ones is so unlikely as to never happen.

Genetic divergence can also happen in situations where the number of organisms involved is small. This might arise from a locality effect, in which the planet is divided into a huge number of locations, some small and some large, and the organisms that evolve in each are different. In some particularly small locations, a genetic mutation might be favored, and then built upon with more mutations, leading to an organism which can then break out of this small location and propagate widely. If there are only a small number of organism in the location where this is happening, it might happen on one clone Earth and not another. This is a second mechanism by which some genetic differences between the two planets can occur.

A third, related situation, can happen in large localities, but ones in which change is rapidly happening. If the location is modified somehow in a evolutionarily short period, changes might happen there on one clone Earth and not on another. Some particular mutation occurs on one of the planets, and would have eventually occurred on the other, except that the location changed. This particular mutation wins the fitness competition in the short-lasting location on the planet where it happened, but the location disappeared or changed its conditions so that if the same mutation happened on the second clone Earth, the mutation would not have been successful. Something in the environment had changed so that what was optimal for a period was no longer optimal.

There are undoubtedly many ways in which two identical planets can evolve different sets of organisms with different genetic codes. However, what should be the same is the filling of evolutionary niches. Given enough time, some organism will evolve to take advantage of an energy source or a materials source. On two clone Earths, these organisms might differ genetically either in some minor ways or even some major ways, but the functionality would be the same. If there is some location where photosynthesis would work and produce enough energy for an organism to reproduce and multiply, it ill happen eventually. If there is some organism which can be used for food, something will arise to consume it. If there is some creature which might become the prey of another, it will do so. Thus, science fiction writers who imagine worlds which appear like Earth, even ones where humans could survive environmentally, but with strange crops and strange animals, they are well within the bounds of reality. There might not be any clone Earths, or there could be many, but they would not necessarily have recognizable flora and fauna. Since human digestive systems break down organic materials into basics such as sugars and amino acids, humans might even be able to eat some of the vegetation or the animals there, barring toxic components.

Saturday, September 3, 2016

Combinatorical Templating

Biological evolution seems a bit easier to understand than chemical evolution, which is what happens to create the first biological cell, defined as having some coded genetic information used to make new cells. The basic principle is the same, that a simple change occurs, and then an increase in fitness happens or it doesn’t. When a change happens so fitness increases, the change has to stick.

In the origin of life theory concocted here, called organic oceans, the first thing to form is a membrane of ambiphilic molecules on the meniscus between the organic ocean and the water ocean. If the theory is to be complete, there has to be some pathway from this to a biological cell. A lot of guesswork has to go into finding some simple step that can lead away from this first stopping place.

One simple step is the concatenation of a chain of amino acids attached to a strand of the membrane. These would build up only if energized by something in solution before they reach the attachment point, so the process would be slow. Evolution is a billion year thing, however, so slow is not an objection. If there are chains formed, and they cross-link, there is some structure that might fold over the membrane into something like a tube. This increases the cross-sectional area for more attachment area from a thin layer below the membrane to the size of the tube, which can be much larger. This is certainly a fitness improvement. Random attachment can go on, but there has to be replication as part of this puzzle, so only those attachments which can template themselves or in a group will replicate, and then when the membrane tears into two, these auto-templating ones will be the ones to be present on both pieces, as a form of reproduction.

The big problem with chemical evolution is the transition to biological evolution. Templating is a simple means of replication, but some simple steps have to be found to transform it into coded replication. The current means of tRNA and mRNA, ribosomes and ATP, etc. doesn’t have to spring into being all at once, but what is needed is some simple initial steps that will get the process started.

Here’s the rub. A genetic code has to do two things: it has to replicate itself when the cell it is in reproduces, and it has to generate other things in the meantime. Templating only does the first thing, not the second. So something a little more complicated has to be thought of. Consider group templating. Molecule A is a template for molecule B and molecule B is a template for molecule A. As many molecules can be inserted into this chain as desired, but it still does not break loose of the original set of molecules. Suppose templating to make molecule Z needs two molecules, X and Y. Maybe X and Z together produce Y and Y and Z together make X. Still no progress is expanding generation of molecules beyond what is the starting set.

Suppose Z does need X and Y, but some fourth molecule, W, is needed in combination with Z to make X and in combination with X to produce Y. W and Y make W, so replication of the originals is complete. Now suppose that Z and X make A and Z and Y make B. Now there is production outside of the original set. In other words, there can be schemes for production of other molecules as long as four molecules are present in the original set. So, to fill in the details of such a proposal, there would have to be some way in which two molecules interact in order to produce one molecule, the same or different, and there has to be sufficient participants to produce more than the original numbers, which easily happens with combinatorics. A thousand different schemes can be thought of, with molecules K, L and M working together to produce J, and J alone produces K, and so on and so on. The general idea is simply that with combinatorics, the hurdle of moving with templating beyond some original set of molecules is passed.

Other types of schemes are certainly possible, for example, two-state schemes. Suppose molecule A produces molecule A when it is in one state, but it produces molecule B when in the other state. It could be a state controlled by the torsion on a carbon chain, or polarization caused by some other molecule, or something else entirely, methylation or some other modification. It could be something as intriguing as a molecule being quite long, and folding back on itself in a loop to make one molecule, but staying straight to replicate itself.

Replication undoubtedly needs energy, so there has to be some scheme, involving some other molecule, to activate molecules which will participate in replicate, either of themselves or something different. This is another aspect of what has to go on next to the original membrane.

It doesn’t seem really necessary that the molecules involved be completely detached. As chemical evolution proceeds, perhaps two of them, say A and B, join, and when C, with a frontal length that matches A and B separately, connects to either A or B, the requisite production happens. If there is another molecule, D, which just moves C from A to B, we have the absolutely simplest abstraction of a ribosome. And if it is necessary that molecule E join with C before can do the replication with A and F must join for B, then we have the simplest abstraction of tRNA.

It might be possible to do some simple experiments to find out about what membranes could form in this hypothetical situation, and then to see what is necessary to have concatenation with something like an amino acid. These experimental steps would have to be worked through before any replication experiments were started, but with the knowledge of how to bind the template molecules to some experimental apparatus, replication might be studied in a laboratory setting as well. These would represent the first tiny steps toward understanding the real origination of life processes.

Friday, September 2, 2016

There are no SuperAliens

Mankind has conceived of superbeings for as long as there have been clans and conversation. Once humans learned to talk and then to try and figure out the reasons for whatever they saw, they imputed some happenings to the work of superbeings. The earliest mental use of superbeings was to try and organize the world. Humans learned to conceptualize individuals, such as members of the clan, and then they connected things that happened with individuals which did them. It is only a short step to guessing there are other beings outside the clan that do other things. Animals were anthromorphized and thought to have thoughts and plans just like humans; some animals were thought to have powers beyond their actual abilities.

Humans and animals can hide or choose not to show themselves, so why wouldn’t there be superbeings that do the same thing. Now we get to Apollo, Thor, and a plethora of other humanoid superbeings with powers that humans do not have, or an exaggeration of human powers. These imaginary creatures allow a human to interpret things that happen, such as sunrise and lightning. Castes arise which claim to communicate with the superbeings, which just makes the beliefs in them more robust.

We have progressed beyond this level, but the huge amount of stories, books, videos, cartoons, and other media involving superbeings of various kinds testifies to the continuing attractiveness of such conceptual beings, even if there has to be a temporary suspension of disbelief during the telling of the story. The human brain is very capable of being inconsistent, and while we can understand the impossibility of flying people, that does not prevent large fractions of the people from enjoying Superman comics and movies.

Someone who doesn’t know the impossibility of a flying Superman might think that such a being was possible. Similarly, someone who doesn’t know the impossibility of aliens who have hidden machines at their beck and call to burn holes in walls or transport them anywhere in no time at all or tell them facts they have no ability to perceive or whatever, might think there might be such beings somewhere.

It takes a broad scientific background to appreciate what an alien or a civilization made up of aliens could actually accomplish and what would be beyond their capabilities. Traveling here from some planet a few hundred light years away is possible, just extremely difficult. Newton figured out the basics of this more than four centuries ago, and in that time, only high-energy exceptions have been found. There is a certain amount of energy needed to travel, and the energy requirements grow inversely with the time to do it. Relativity just says that the energy requirements get worse and worse as speed approaches light speed. General relativity says there might be some percentage shortening of path lengths if you have enough energy to make something like a large black hole. Would an alien civilization be able to muster up this level of energy, almost ridiculously large, and then expend it to have a few citizens take a trip to another star? Traveling at a fraction of light speed is certainly energy-expensive enough. Once it is understood that aliens would have a long travel time, the concept of superbeing shrinks in size down to something closer to human.

The same goes for the sending of information. Information has no mass, but it must be carried by something that has mass-energy, so the carrier is limited in speed. That means that aliens visiting us would not be able to call home. Another problem with communicating between stars is the r-squared law. Power density decreases as the square of the distance of communication. This is beaten down somewhat by having an antenna that squeezes the energy into a tiny angle, but antennas have diffraction limits and must be huge to do this. You don’t do it with a cellphone sized gizmo.

Antigravity poses a problem as well, in that the energy requirements are large and unmanageable for anything as small as a starship. This is only a problem for film production, however, as a little genetic manipulation should be able to make aliens who tolerate zero-gravity or simulated gravity well. There is a bit of overlooked difficulty in accelerating to high speed in short times, in that the g-load in a ship trying to do this would be large. It is possible to cushion biological organisms against some g-loading, but not a hundred times normal. The same would hold in deceleration. A ship making the trip from one star to another might have to commit long times for acceleration and deceleration. Sudden turns just don’t work well at high speeds as well.

Another aspect that creators of superalien stories like to give out is advanced intelligence. Intelligence is data processing, and if a huge database is needed, storing it in a neural network is pretty efficient. Maybe aliens could have genetically found ways to make neurons transmit pulses faster, but not that much, and how to make more branches work on some types of neurons, but not much. The human brain has a tremendous capability for data processing, although it is almost never used to its full extent. An alien brain might be better, but not by factors of ten. Data retrieval could be expedited by connecting the alien, via an internal communication device, to some sequential processing system, but then the communication mechanism creates a limitation on mobility outside of the networked area for this system. On an alien home planet, this might be fine and demonstrable, or even on a large ship if the aliens had the resources to build and send one out, but for wandering around far from anything substantial there would only be the biological capability.

For enjoyable stories, superaliens make great characters, but for a civilization like that of the Earth, thinking about preparing for the possibility that there might be some contact, superalien stories might be misleading and actually interfere with any planning for it. There is a great deal that can be figured out about alien potentials, as this blog tries to do, and realism is perhaps one of the most necessary attributes of any such planning.