Monday, June 29, 2015

What Makes a Great Filter?

There are a lot of collections of Great Filter possibilities.  Many clever ideas have been expressed.  Not too much has been written about the Great Filter process, however.  This blog post is an attempt to contribute to that lack.

One of the usual arguments for a Great Filter candidate is that it took a lot of time for some particular transition to take place and therefore it is unlikely to happen and therefore it might be the Great Filter everyone is looking for.  Let’s explore this concept a bit further.  Suppose you have a planet in some state, along the presumed pathway from just rock and stuff to star-travelling lifeforms.  Someone seizes on some definition of a state, State 1, and a later state, State 2, deemed to be the next one, and notices there was a lot of time between them.  A Great Filter?  Perhaps this is just a lack of knowledge of what the intermediate states were.  If our science knew fifteen steps between the State 1 and State 2, maybe State 1a, State 1b, and so on, there would be less time between states.  The declarer of a Great State concept would have to pick one transition, say State 1g to State 1h, and show that was difficult or required unusual conditions or took almost all of the time formerly allotted to the State 1 to State 2 transition.
Thus, is ignorance of the details of a pathway sufficient to call something a possible Great Filter?  Hardly.  The point of the Great Filter is that many worlds wind up with the predecessor state, here State 1g, and very, very few wind up in the successor state, here State 1h.  Lack of knowledge does not translate into knowledge very easily.  Because two states are easy to describe does not mean they are particularly interesting stopping points unless we knew the details of the processes that led to each of them, and that followed from each of them.

Another argument for a Great Filter is the number of unique conditions that must simultaneously happen.  If we know the transition from State 3 to State 4, ignoring the just-discussed problems of deciding on just what those states are, we have the problem of showing that the unique conditions are really rare.  Suppose that the transition from State 3 to State 4 requires five things to be around in the neighborhood where the first exemplar of State 4 arises.  In other words, detailed knowledge of how the transition works means that each of five conditions, like temperature, pH, lack of wind, or whatever, or constituents, like Fe, Vitamin A, H2SO4, or whatever, or environmental changes that drive the biological  change, like drought, disappearance of cloud cover, dissolved oxygen, or whatever, or something else other than a condition, constituent or environmental change was necessary and rare.  If we don’t have detailed knowledge of the transition there is no way to get a count.  Guessing might be done in the absence of knowledge, and we will have a potential Great Filter, but some other guess might produce others and we have no Small Filter to filter out the guessed Great Filter ideas. 

For a promotion from Great Filter guess to Great Filter candidate, there would also have to be accompanying knowledge that the five, to keep with the number in the example, conditions, constituents, changes or whatever else were actually rare.  If the arguments on why something should be a Great Filter candidate depend on what we have here on Earth, we would need the rarity to be the case in space and time, in other words, while looking over the whole planet and over the whole transition time.  If these five conditions keep arising over and over, or during one shorter period all over the planet, even though it might seem to be a difficult transition, it is actually easy.   

If instead, the arguments are made that our planet is what is unique, we have at this point even less data upon which to base an argument for a Great Filter candidate.  This raises the question as to whether the concept of a Great Filter is anything more than an indication that in a string of probabilities relating to the prevalence of life, it could be true that one could be very, very small, as opposed to many of them being pretty small.  What actual benefit does the concept of the Great Filter provide?  We do not have any data to decide where the steps are, what the requirements are for each, what the statistics of the prevalence of the required conditions are, or anything else. 

There is one exception.  If a Great Filter concept relates to something we already know about or can figure out in short order, we can evaluate it and see if it is actually likely to be a Great Filter candidate.  If we are able to figure out if the concept would stop a planet from giving rise to interstellar tourists, then we can narrow down the candidates list.  Of course, there could be two or many Great Filters, but none quite as decisive as if there was only one.

This means that reasonable Great Filter candidates can come from anthropology rather than the era of the synthesis of various stages of life.  We can look at a lot of anthropology, as we are living through some, and we have records to varying degrees of failed societies, ones which might have headed off to become the originator of stellar voyagers, but which instead collapsed or dissipated away.  We might also seek Great Filter candidates from our own history, which has a fuzzy boundary with anthropology.  Here we have a chance of collecting the data needed for evaluation.

We might also use our knowledge of science and technology, limited as it is, to look for Great Filter concepts arising from these arenas.  Is there some unique invention or discovery which was done by pure chance and which made a great difference in how history developed? 

One last point is that the synthesis of life is a vital and interesting scientific question, and why it is not being pursued with great vigor and huge blocks of funding, with crowds of grad students competing to participate?   Science gets a lot of funding, but why does it go into understanding physics particles rather than our own ancestry?

Sunday, June 28, 2015

The Happy Life Great Filter

A number of people have written about the Great Filter, which is supposed to be the stumbling block between non-life and exploring the stars.  [If you want to know who, google it; references are a bit passé]  It is a term coined to answer something called the Fermi paradox, which wonders why there aren’t any aliens around now.  If you’ve got a Great Filter, all those myriad planets never manage to send out spaceships to explore Earth and other places in the galaxy. 

The writers like to organize their thoughts into some common possibilities, ranging from it being hard for any self-replicating stuff to form at the very beginning, through some evolutionary stages, some of which are deemed harder than others, up to the launch of the ships, which might be a very difficult thing.  We sure don’t know how to do it, but we keep learning things, so maybe it will be possible some year in the future.  Maybe it’s too costly, or space is a bad place to even travel through or something else might happen when we start to travel to other stars.  This is the final phase of the proposed natural sequence of life, and if, for example, space is pretty hostile to spaceships for reasons we don’t know yet, that could be the Great Filter that has prevented any alien people from coming here to greet us.

Some of the writers about the Great Filter say that if it lies behind us, and we have somehow been the lucky planet to get through, and that this is a relief, because we don’t have the Great Filter in front of us, which could be a catastrophic event, like the first ship always blowing up and contaminating the atmosphere of the launching planet, eradicating life.  Actually, this is not a real listed possibility, but it captures the idea. 

I think of the Great Filter being in front of us, and it being a Happy Life.  As we get more and more control of things on the planet, we can expect that people will have happy lives, meaning, adequate food, water, beverages, clothing, homes and hotels, shows to watch, places to exercise, friends to have dinner with, good medical care, music, and so on.  Make your own list.  The point is that, once we get a bit farther down in history, it will be a pretty nice planet to live on.  Right now there are problems that a lot of people suffer from, arising from us not knowing how to match population to resource availability, a bit of ignorance about sustainability, lack of interest in recycling, and so on.  But these will get solved as we go forward into what will become history.  When we have a good life, why are we going to go build a ship to go to some other solar system?  Wouldn’t it be easier to forget about that stuff and watch the latest media release?

If everybody has a great life, and we have some preparations in hand for tsunamis and hurricanes, tornadoes and earthquakes, volcanoes and sinkholes, asteroids and plagues, and anything else that might disturb us, what is the point of blasting off for unknown parts?  We might even forget to reproduce and so the population would decline, and maybe even disappear.  Those of us who lived in the Happy Life time, which might go on for ever, meaning millennia after millennia, would have little reason to worry about anything except what is on the menu tomorrow or which cocktail you wanted to have after dinner. 

So a plausible Great Filter is just success at figuring out how to solve life’s problems, which is what we are doing with a lot of gusto.  Once we get a bit further into solving the local problems, we may lose interest in distant ones that might be happening in outer space.  If someone was interested in outer space, they could play a video game with good virtual reality or watch a multisensory media presentation showing some simulated people doing some simulated things on some simulated distant planet, with or without aliens present.  It might even be that we could have a very advanced version of Netflix, where the system creates a media presentation in response to an individual’s requests and tailors it to his interests.  Satisfaction of all needs eliminates all needs, and eliminates specifically the need to bother oneself about other planets.

Perhaps every culture that gets to be intelligent finds that intelligence, after a few millennia, manages to put together an environment that cares for all the individuals present on the planet, nurtures them, and entertains them so well that they would never even think of wanting to go exploring somewhere in the real world, like a planet that would take years to get to.  Nor would they care about building some robotic thing to go out and do it.  Why not simulate an exo-planet rather than go visit it?

So there is no need to fear a Great Filter in our future, as it may just be a Happy Life coming for all present.  Is there any reason to wish that the Happy Life does not come, or that it is not so fulfilling that other goals are forgotten and ignored?  This is a philosophical question, and perhaps intelligent alien civilizations have all dealt with it, and answered it in such a way that they are content if the entire population is living the Happy Life and not playing space explorer.  Simulation is so much cheaper than actually going out there and returning some data.  Perhaps we should discuss the philosophy part again, in connection with the memes that might be the only antidote to the Happy Life.  Another blog post on the horizon…

Roadblocks to Asymptotic Technology

Asymptotic technology is what you have when you finish science and have explored technology to its creative boundaries.  Maybe it would take a civilization a millennium to do so, maybe a factor of ten from this depending on all the circumstantial details of the civilization.  The point is that science is the same for all civilizations, and that anything that can be figured out will be figured out, if science and engineering progress is maintained.  Doing experiments or observations or theoretical calculations or other science development work takes time, but the details of the work are a function not of the civilization, but of the scientific questions.  For example, learning to separate transplutonics requires some effort, some thinking, some equipment, some materials, but these requirements don’t depend on the civilization that is learning this.  One civilization might have sharper people than another, or be more forthcoming with the money for the equipment, or be more prone to making mistakes, and many other factors could serve to determine the exact amount of effort and other items that this example of learning might take.  So perhaps there is a factor of ten up or down in the time it takes a civilization to do this and to come up with their knowledge of transplutonics separation.  But there is not a factor of a thousand up or down.  The science has a great influence on the time, not the civilization.  The amount of knowledge necessary to put together theories and specific data, such as ionization potentials for each element, is dependent on the world of science, not the world of the scientists to the orders of magnitude we are discussing.

Of course, the civilization could decide to stop doing science, to delay studying transplutonics or some other example for a while, or there could be a social breakdown taking a century to recover or many other things could happen to change the date when the civilization finishes its scientific work.  The society could exterminate itself, and the time to finish science could be indeterminate, as it doesn’t happen.  But under the assumption that the society continues at an advanced technology level, the time needed to finish their science and engineering work is pretty small, compared to other times, such as the lifetime of a star. 

Furthermore, the science that civilization A finds will be just exactly the same as civilization B finds.  Exactly.  Of course there could be errors made by civilization A, but we are discussing asymptotic technology, after the errors have been reduced to a tiny amount.  So, after a time of the order of millennia, asymptotic technology gets wrapped up by a civilization that chooses to and doesn’t wreck its own social infrastructure too many times. 

Is it possible that a civilization might not get there, and it instead reaches some plateau where it stays until it expires?  Could it lose some of its technology and decline in capability?   This blog post discusses how this might happen, and what might cause it. 

The alternative for a civilization that deliberately stops along the way to asymptotic technology is that it may regress, gradually losing its knowledge and the capability to use it.  It would seem that stability at a plateau is much less likely, as if the society which is in stasis undergoes some transition, they could jump back on the track to asymptotic technology.  On the other hand, if the factors which are preventing technology from advancing grow a little stronger, some more technology could be abandoned or lost.  So perhaps it is reasonable to conclude that a civilization would have to make a collective decision to stop technological development at some fixed point in some fashion and then work to preserve what had been done so far.  They could alternatively choose to maintain only a subset of it.  Yet even with a collective decision, there would still have to be scientists charged with preserving what was not proscribed, and they would be around if that collective decision was abandoned after a century or some short time, and able to start the process of science and technology development again.  If the number of scientists or the quality of their training declined, then the residual technology available to the society would decline, leaving the plateau in the other direction.

So, a little bit of thinking about what a society attempting to stay on a plateau would have to do indicates that the plateau is unstable, and easy to depart from.  Having a peak and a decline would seem more likely.

So, a better way to frame the question about reaching asymptotic technology is to ask what might cause a society to reach a peak of scientific and engineering knowledge and then start losing it.  Perhaps the loss would be slow, as measured in millennia, or fast, as measured in centuries.  We leave aside how to measure the amount of scientific knowledge the society has, as our understanding of what the ultimate of science is remains unclear. 

To build up science and engineering, the civilization needs thinking beings, access to observational data, equipment of a large number of types, funding to pay for all the work and materials, and some places to do so.  It needs a way for those involved in science and engineering to have their work checked and validated, and then gradually improved upon.   This means a mass of other scientists and engineers.  There are other things it needs.  In order to have no holes in science, there has to be permission granted by society, in terms of hard control or in terms of funding, to study anything.  Scientists and engineers are embedded in the civilization, and if the civilization has, for example, memes which prohibit the asking of certain questions, for example examining the nature of the sun god, then for as long as these memes hold sway, science cannot reach its ultimate level.  In this example, knowledge about the sun and all the things that it feeds into would be unavailable.     

If for some reason, thinking beings continue to decline in number, the rate at which science will progress must drop and then pass below a critical threshold.  If all the beings are thinking, but their population declines, or if only some subset is capable of thinking at a scientific frontier level and the population of this subset declines, science will peak and decline.

If there are restrictions on observations and experiments, science will work around it but holes will be left in the body of scientific knowledge and engineering know-how.  The size of the holes will determine the damage this does, and just as a plateau was unstable, these holes may grow or shrink with time as the decades and centuries pass.  Funding may be a problem, and if the society does not become sufficiently productive, more expensive experiments and observations will not be possible.  So, if for any reason the economy contracts, science can peak and decline, as the trained population diminishes, or the things which they can do is further restricted by the need to use the products of the society elsewhere.

Thus, there are two roadblocks to the achievement of asymptotic technology that are easy to see, and other ones appear to be unstable and not likely to be a conclusive obstacle, or else turn into one of the two main ones.  The first is the loss of creatures able to think clearly.  The second is the loss of productivity of society.  Either of these will result in a scientific peak and then a decline, and if they are both avoided, asymptotic technology should be achieved, without holes in it, as limitation memes are likely to be eroded with time.

This implies that any alien civilization with star-faring capability will have the same technology.  Perhaps star-faring will be possible at the 90% level of technology, but since interstellar travel is likely to take centuries, unless faster than light travel is feasible, the remaining technology will be just about wrapped up by the time they reach their destination.  

Friday, June 26, 2015

Interstellar Communication

With distances between possible habitable planets or even between resource-rich planets used for stopovers or as some other type of outpost being of the order of tens of light years, communication between planets in different solar systems is of a very different character than communication within a solar system.  In a local environment like a solar system, travel times are a few hours at most, and may be only minutes for close-in planets.  In this environment, communication back and forth is little different than communication via certain media on a single planet.  For us, it would be like getting emails.  But with, say, 20 years between messages, communication like this is absurd and therefore, only a few special types of situations would involve it.

One situation that has already been discussed is exploration and colonization.  The least expensive way to get initial close-in information about a potentially useful exo-planet is to do a high-speed fly-by.  Then the fuel needed to decelerate the probe is not needed, and this drops the weight and size requirements considerably.  But unless the probe can communicate back to the sending planet, and transmit quite a lot of data, the probe would have to decelerate and return home with its collected information.  No fly-by means a lot more expense, including design work, testing, equipping and so on.  So it would be important to see if communication between different star systems is possible, and if it is, is it possible at a data rate high enough to be useful.

A consequent question is how big and massive a communications package would have to be.  For an sufficiently intelligent autonomous probe, there would be no need to make a receiver on the probe, only a transmitter to send the collected data back to the originating planet, and perhaps some status signals to let them know that things are going as planned and that there is no need to send a replacement.  If the equipment, including pointing control, antennas or integral transmitters, signal generators, power supplies and fuel, and anything else an advanced civilization would build into the system, is more massive than the burden involved in deceleration and return of the probe, then communication is not necessarily a good option.  It does cut down the time, as a probe that decelerates starting half-way through its voyage will have a longer travel time than one which accelerates all the way there or which cruises for the second half of the voyage, and getting the message back by speed-of-light communications is much faster than having the probe make the return voyage home.  The difference in time is measured in centuries. 

It is hard to make analogies between Earth’s situation and that of an advanced civilization, past the asymptotic technology transition.  Nevertheless, here we have grown accustomed to waiting years for an interplanetary probe to reach its destination and communicate back pictures and scientific measurements of the planet.  The Pluto probe, New Horizons, has a nine-year flight trajectory.  Perhaps an advanced civilization, with probably markedly greater longevity, could tolerate a 400 year probe return with no repercussions.  Such a civilization should be completely stable, so questions of whether an organization to manage the probe or even a nation might exist at the return time of the probe are not relevant.  If the civilization is one with an expansion meme, there might be some pressure to take the fastest solution, but the launch would likely be after a long period of stability, and so social pressure for anything may be almost non-existent and the best solution for the probe design, measured in reliability, data capture capability, total mass, consumption of resources, or whatever matters, should be the basis for the choice of design.  In other words, nothing much changes in the society so there is no hunger for faster change.

The other situation previously discussed that could make very good use of interstellar communication is that of deterrence.  The timing of this is unlikely, but it could be possible that there are two interstellar civilizations in proximity, and at least one of them is predatory, by which we mean that it would like to eradicate the other and occupy its home world or collection of colonized planets.  The other civilization, either being predatory and in conflict with the first, or non-predatory and wanting to be left alone, might want to depend on deterrence to prevent the first from carrying out the eradication.  It seems that one likely type of weapon for interstellar conflict would be large explosive devices, and the second civilization would want to detect the attack on itself with enough warning so it could do what it could for passive defense, and what it could for active defense, but also counterstrike.  With a counterstrike capability, some deterrence exists. 

Two different situations can be distinguished.  The two civilizations could exist in about the same numbers, meaning worlds occupied and inhabited, or one could be substantially larger than the other.  Remember that there is not likely to be any trade whatsoever between the different worlds with the same origin planet.  The economics are prohibitive for resources transfers, and all the worlds have the same background, and asymptotic technology has penetrated art and anything else that more primitive cultures might trade, so that there is nothing traveling between the worlds with the same origin, those of one civilization entirely, and they are roughly independent.  There may be traditions, but governing a planet from 20 light years away is hard to envision.  

The situation where one civilization is on the edge of the expanding wave of colonized planets of the other, perhaps older, civilization is more intriguing.  The simpler case should be discussed first.

If there is only one planet or solar system each for the two civilizations, deterrence might be done by having surveillance posts somewhere in each other’s solar system, monitoring for the launch of attack vessels in the direction of the other world.  The surveillance posts can be covert, if possible, as destroying them would disable deterrence and allow an attack to proceed with much less warning.  Alternatively, they could be known and built under some agreement.  But agreements can be broken and they could be destroyed.  Thus, there are some unique requirements for a surveillance station.  It should, first and foremost, be designed to provide a warning signal with a very high confidence.  The signal is something that says “Attack” when an attack is detected.  The station needs to be defended or at least its neighborhood monitored for incoming vessels or beamed weapons so that an attack on the station cannot be done without the “Attack” signal being issued with high reliability and high confidence that it will be received.

Since the attacks take decades to conclude, while the explosive devices travel to the other civilization’s planet, there is plenty of time to act.  Similar explosive devices could be launched toward the other civilization’s planet.  This is the essence of what we used to call, during the Cold War here on Earth, Mutual Assured Destruction.  If it works, no one attacks.

To guard against the possibility of a surprise attack being successful on the surveillance monitor station, some things might be done.  One is to have several, each monitoring the others.  Another is to have ‘Peace’ messages send out from each surveillance station to the origin world.  There would have to be sufficient encryption on both the ‘Peace’ message and the ‘Attack’ message that they could not be duplicated, and of course, high degrees of security so that the cryptography could not be compromised.  This also provides a defense against a cloaking attack, where the predatory nation detonates something to make a cloud of absorbing particles on the line of sight from the surveillance station to the origin world.

The requirements for interstellar communication between a surveillance station and its home world are quite different than for that of an expeditionary probe.  A coded message must be sent, perhaps several times a year, only containing a single binary bit of information: ‘Peace’ or ‘Attack’.  The power transmission requirements might be the same, or perhaps of higher power for more assurance with surveillance.  A probe can be done over.  A defense cannot.

The alternative situation described above, where one civilization is outnumbered by the colonized worlds of the other, calls for some discrimination.  Which of the worlds of the larger civilization does the threatened civilization point its deterrent weapons against?  Can it provide surveillance stations on all of them?  Is there some distance limit, so that it monitors those within 40 light years but not the other further ones?  Does it need to provide deterrence against a simultaneous attack by multiple worlds of the larger civilization? 

These two scenarios provide us with some ideas of what the requirements for alien interstellar communication are.  Is it possible, with the limited knowledge of technology we have, that some conclusions can be made about what is feasible for meeting these requirements and what is not?  It remains to be seen, but not in this post.  However, if we knew, we might have a better idea of what to look for in the galaxy as a signature of an advanced civilization and therefore this is an interesting area to explore.  

Thursday, June 25, 2015

Reconnaissance in Star-traveling Alien Civilizations

Reconnaissance is the collecting of information.  This blog is about what an alien civilization, either an expanding one or a contracting or stable one, would want to do.  The focus is on a civilization that has achieved the ability to travel across interstellar distances, and has already reached asymptotic technology, where they can do everything that can be done, in the most effective way.  Recall that the transition happens fast, going from virtually no scientific and technical knowledge beyond some agricultural know-how to having it all, in understandable and organized form, in millennia at the most, an instant in the life of the universe.  Recall also that the scientific theory part of the asymptotic technology transition does not provide data about the universe, only about the laws that govern it.  Reconnaissance is the getting of the data.

For a civilization that has the meme of interstellar dispersion and is either on the verge of their first expedition to another solar system, or has already done it and is going to continue doing it, reconnaissance is mandatory.  Reconnaissance at the earliest stage is simply another name for astronomy of nearby solar systems, and would be done so they can find the one that is best suited for their first or next interstellar voyage.  We can project that a civilization at this stage can build an array of large telescopes in space, isolated from their own planet and other planets in the solar system, operating in the UV to IR range, of sufficient size to look at exo-planets orbiting nearby stars.  Think of the size of each reflector as kilometers and the whole array strung around an orbit the size of Earth’s, which determines the aperture.  With this aperture, and as long to look as they want to, they could possibly determine continent-sized details on the planet.  More importantly, they can do spectroscopic analysis of the atmosphere, learn something about the winds, see if there are oceans, and in general get many other chunks of information. 

With all science already learned, the data can be used to fill in the details of models of planets.  With the star understood well, and the planets to some degree, knowledge of how planets form can be used to fill in more information about the planets.  A consistent picture of each observed planet can be developed, and some good estimates of what is there built up.

One of the interesting chunks of data is about the signatures of life on an exo-planet.  Life as we know it has some chemical signatures that might be detected.  With asymptotic technology passed, meaning science is known, the question of what forms of life are possible should be answered completely.  If there are multiple forms, they might have multiple types of signatures, which can be independently checked.  There might even be some indication of what stage life was in, whether it was simply single celled or whether there were animals walking on any dry surfaces.  Perhaps the signatures for animal life are not sufficiently distinct to be discerned remotely. 

While  telescopic reconnaissance from the home solar system can continue, this much information allows a selection of targets to be found for reconnaissance voyages.  Assuming their meme is directing them toward a future habitat, they would select those planets that most closely match what they require, or which could be altered using the technology they can transport to the exo-planet into something close to what they need.  It would be nice to have a Garden of Eden awaiting their arrival, but the bottom line is that the exo-planet must have resources available to sustain their form of life.  They can build hermetically sealed shelters and vehicles if necessary, but they cannot truck all the materials needed to sustain a civilization in large numbers across interstellar distances.  This is the deciding criteria.  Does it have the resources needed?

Resources include an energy supply and materials needed for every aspect of life.  Any space-faring civilization would need to master at least D-D fusion to power their spaceships, so as long as there is hydrogen around in the atmosphere of some planet in the new solar system or in water or another chemical on the surface of some planet, preferably the one they chose for their possible habitat, they can have fuel for a fusion reactor.  They also need all the minerals needed for life support, for habitat construction, for infrastructure construction, and eventually for a spaceport and a spaceship construction facility.  To find out if there are such minerals available, a closer look is needed. 
Sending a reconnaissance ship out to observe at a closer distance might be sufficient, provided that the knowledge of how planets form is so robust that some better data taken by the ship can decide what the planet is composed of and how accessible the minerals might be.  We don’t know at this point in our scientific trajectory if planets can be easily categorized, and, for example, the crust is predictable from the knowledge of the orbital radius, the observable details of the sun, perhaps some details from other planets in the same solar system, and what can be observed from the planet itself. 

There is a question of how accurate the information must be to fully inform the model.  Is a fly-by at a few astronomical units sufficient to get whatever is needed, or is it necessary to get closer or perhaps go into an orbit around the planet itself?  Perhaps the type of atmosphere present controls what is necessary.  A planet with a permanent cloud cover would not give off any information about the surface, just the atmospheric layer where the clouds resided, and for this, sending some vehicle under the cloud layer would likely be necessary.  Perhaps having a cloud layer is sufficient to eliminate the planet from consideration, or perhaps it is a good sign that something valuable lies under the clouds. 

Another facet is how much time is needed for observations.  If the planet has seasons, it might be necessary to have a whole year of data collection, to make sure there are not killer storms that occur during one of the seasons, or that the distribution of temperatures is reasonable throughout the year, or that flooding isn’t an issue, or something else.  This would require the surveillance craft to slow down from the travel speed it used to get to the new solar system.  A previous blog post has indicated that a reasonable speed range is 0.1 to 10% of light speed, and that would have the craft across the planetary orbit too quickly.  If deceleration is not needed, the ship is much more efficient, as the fuel needed for deceleration is about what is needed for acceleration alone, and this much more than doubles the ship size. 

The other aspect of efficient reconnaissance involves whether the craft has to be ‘manned’ with aliens or whether it can be fully autonomous.  Having a crew, even a sleeping crew, raises the payload mass greatly, so if the ship can be made autonomous, it would be.  If the culture of the alien civilization was such that the crew needed to be returned, fuel and mass requirements grow to many, many times what they would be for the minimal reconnaissance voyager, a full speed fly-by.  Probably the alien civilization is forced into the same pattern of travel that we might use in interplanetary travel, if we ever accomplish it.  Autonomous reconnaissance robots first, and then, crewed vessels. 

Our planet might be high on any nearby civilization’s selection list as potential habitats.  We have been able to make observations of our solar system only for a very, very short time, so it is not likely that a spaceship would be traveling through on a high speed flyby while we are able to witness it.  It is also not clear that we have thought through how to detect such a reconnaissance vehicle as it sped by, perhaps at an orbital radius like Jupiter’s.  

Interstellar Alien Populations

There are many things that could be discussed under this blog post’s title.  The number of planets with intelligent life on them in the galaxy would make an interesting exercise.  How many planets a single alien civilization could spread to is another.  A third might be how many different species of interstellar aliens there could be in the galaxy, one or many?  But it’s about none of these.

This blog is about how an alien civilization might choose how large a population it wants on a single planet, or moon, or wherever they have aliens.  The first thing to discuss is about choosing the number.  It does no good for some intelligent alien, or group of them, or a master computer, or an artificial intelligence serving as an advisor, or whatever it is that figures things out there, to decide what would be an optimal population if there was no way to achieve it.  There are obviously two sides to the problem.  The existing population might be lower than desired and decreasing or the existing population might be higher than desired and increasing.  Or, it could be at optimal and is being maintained there. 

On their home world, we can assume it was evolution that produced the intelligent life that mastered interstellar travel.  The world probably started with some rock and some water, some atmosphere and some solar radiation, and through one mechanism or another, self-replicating somethings formed once and then started to mutate.  It may have been a simple process or a very unusual combination of events.  Right now we don’t know.   We may find out soon by a lucky guess, or it might take a while, but the details of this are not relevant to the population of evolved aliens, except for one aspect.  In order for evolution to take place, the reproduction rate must exceed the stable maintenance rate.  Thus, for some period from the start of life up to the invention of contraception or some other population control concept by an intelligent species, the growth rate of some organisms must be higher than one, and most likely, for competition of species to occur and a filtering out of the more ‘fit’, most must be.  So growth to the limits of available resources for each species is probably a good assumption, where limits might be imposed by food availability, the existence of predators, the existence of pests or infections, seasonal die-offs, or something else. 

After the development of competent contraception, organisms still using individually controlled biological reproduction might choose individually not to reproduce or to reproduce below the stable maintenance rate, leading to a negative growth rate for population.   If part of the over-riding meme set established in the alien civilization involved population growth, the availability of contraception might have little effect, or if the gene set of the alien population was strongly in favor of reproduction instead of being strongly in favor of the precursors to reproduction, sexual activity, the same result might happen.  So, either there is some social control over reproduction rate or there has to be some meme component which stabilizes population.  However, if it is social control or a meme component, how is the optimal value achieved?  More likely, to be able to choose an optimal population and to achieve and maintain it, reproduction has to be done off-line, so to speak.  So, we can assume that asymptotic technology in the alien civilization has early on mastered artificial gestation, and the society can choose the desired population and achieve it.  Population stabilization is about matching birth and death rates, and death rates in an alien civilization would be reduced, but probably not zeroed out, so births would be necessary.  Right now our technology is too primitive to understand what the limits of longevity might be, so no assessment of birth rates necessary for stabilization of population is possible.  But it is some non-zero number.

What is the basis for choosing a stable population level?  Resources is one possibility.  In a solar system with multiple planets, is each planet running on the resources available on that planet, or is there some interplanetary commerce that fills in gaps in resources on one or more planets?  Since Earth is nowhere near figuring out how to do interplanetary travel efficiently, there is no possible assessment as to which material resources, if any, are worth the costs of transport.  Do we want to ship hydrocarbons from Jupiter to Earth?  It depends on the costs of extracting them from Jupiter’s atmosphere, and then of bringing them down to Earth.  Orbital costs might be a small part of this, as once velocity is achieved near Jupiter, you just wait for a long time and then de-orbit at Earth.  A large ship with a small crew might keep costs down.  However, it is not likely that a substantial fraction of the materials needed for sustenance of a population will come from interplanetary transport.  Perhaps rare ones will, but that still means that some types of resources on the home world or wherever is being contemplated for population control will limit the population level.

Resources available depend on the extraction rate.  There are certain amounts available on the planet, and it would be possible to extract them at a faster or a slower rate.  This would mean a larger or small population could be supported.  But the faster resources are extracted, the sooner the planet’s limits are reached.  This is the nub of the population choice question.

Do the aliens want a billion aliens on the planet for a million years, or a million aliens on the planet for a billion years?  The product is somewhat constant, being the total amount of potentially extractable resource of the single type that is most limiting, and how they use it up is their choice.  Maybe it’s a billion aliens for a thousand years or a million aliens for a million years.  Whatever the limiting resource is, given recycling to the practical limit achievable in asymptotic technology, and not counting ones where interplanetary transport can fill in gaps, some limit exists and the tradeoff between duration of habitation and size of the population has to be made.  The tradeoff can be gradual, for example, a half a billion aliens for a thousand years and then a million aliens for half a million years works just as well as the previous example.  The point to be made is that some basis for choosing the population numbers, as a function of time, needs to be made in order to achieve some goals.  The integral of this curve is assumed near constant.

If the goals, as embodied in the memes and expressed by the civilization’s philosophers, are equivalent to dispersal and survival, the curve for population might be large at the outset, so a generation or two of interstellar exploration and colonization ships could be built and sent out, with checking done that another few worlds have been colonized successfully, and then the world can relax and drop back into a low level of population for survival purposes, in case something happens out in the colonies and they are extinguished.

This population curve is quite different than one for an alien civilization with simply survival as their meme.  Then they could procrastinate, and not build interstellar ships until something was going to go wrong on the home planet, or in the home solar system, and then they would send out interstellar ships to the nearest colonizable world with a seed population.  This might require a ramp-up of population, depending on how production was organized on the planet.  

Thus, if it were possible to envision a population map for a civilization with the dispersion meme, you would see an expanding wave of population, starting with a burst on the home planet, and then dying down behind the wave.  It would look like a three-dimensional equivalent of what you see when you drop a stone in a still pond, except the height of the wave would not diminish as it propagates outward.  The equivalent for a civilization with a survival meme would be reminiscent of a frog jumping from lily pad to lily pad in a pond.  Both are interstellar alien civilizations with equivalent asymptotic technology, but the meme makes all the difference.

Wednesday, June 24, 2015

Interstellar Alien Memes

To remind ourselves, memes are blocks of information in a society that perpetuate themselves, and perhaps also spread.  For example, if you had been taught as a young child, long before the age of reason and before you had any way to critically assess your teaching, to believe a list of things and, in addition, the first one was that every parent or guardian should teach young children they have care of the same list, that would be a meme.   Among societies where there is absolutely no ability to think critically or among partitions of societies where this is true, the example meme can be spread to adults. 

Thus, this blog post is going to discuss what self-replicating sets of beliefs an alien civilization might have that would relate to interstellar exploration and colonization.  If an alien civilization does not have such a meme, they might still choose to spread out through the galaxy for rational reasons, such as economics or security.  The point of this discussion is that even if they do not have those rational reasons, they might still spread because of some credos their society holds which are considered fundamental and unquestionable.  A meme that is inculcated in children may well stay with the individual as an adult, and if it is designed well, and the aliens are suited for such things, it may be unbreakable.

The block of beliefs has, as a mandatory item, that it be propagated to pre-rational children, and, as we are discussing interstellar dispersion, that a mission of the civilization is to spread to other worlds, moons, and wherever else is a viable habitat.  The rest of it has to be self-consistent. 

Does there need to be anything else?  If the meme has achieved the level of a fundamental belief that guides the choices the civilization makes, perhaps it is all that is needed.  It could be phrased as “The destiny of our grand civilization is to conquer the stars.” It could be phrased as “The greatest good for the greatest number drives us to seek homes throughout the galaxy,” and who is going to argue against achieving the greatest good for the greatest number?  Even though it is an arbitrary choice, as memes are by definition, it sounds very convincing.  There might have been authors who expounded on either of these two interstellar dispersion memes at great length.  Stories of individuals or groups who did some initial exploration or colonization could be the equivalent of the Iliad or the Bhagavad Gita, in terms of the respect that the society shows them.  The civilization would have elaborated on the meme, and the beliefs would have seeped into all types of other aspects of the civilization.  Holidays could be structured around interstellar dispersal events.  Social rank could be conditioned on involvement with it.  In short, the meme could be the cornerstone upon which the society is founded.

Alternatively, the concept of colonization of the galaxy could be just one part of a whole scheme of things that the society accepts as fundamental truths.  Some could be consistent and symbiotic with interstellar dispersal.  They could value recycling as a fundamental part of their society, as one of the components of the most accepted meme, and since recycling of everything is likely to be mandatory for long interstellar voyages, this is wholly consistent.  But recycling might be elevated to a value in and of itself.  They recycle even in situations of plentitude.  “Never waste what later generations might need.”  “Protect resources as you would protect yourself.” There could be a number of ways in which the concept is expressed. 

Other components of the meme that would be consistent with the concept of interstellar voyaging would be the structuring of society as an enlarged replica of the command structure of a ship.  Inter-creature relationships might be a mirror of the specific type of behaviors need for long flights together: “Treat each other as if you were shipmates.”  This type of elaboration can be continued, but these two examples give enough of the picture. 

Especially on worlds, moons, and other habitats that were colonized, these memes might have even stronger power than on the home world.  It might be that there was less adulation of the meme on the home world, but everywhere else they were accepted as the fundamental precepts of society.  Alternatively, the home world could be the nest where the meme was first started and propagated, and it took deep root there. 

Here on Earth, there has been little written about dispersing to other planets outside the solar system as there was no evidence of how many of them there might be.  There is a reference in the Lotus Sutra from a lecture by Gautama Buddha on how all the stars are foreign worlds with creatures living there, but it does not seem to have become a prominent aspect of the belief system he founded.  Other than that, nothing is apparent.  But in the current century, such worlds have been detected and some elementary knowledge about them is being collected.  We might expect that a civilization developing might have Buddha’s insight and start fantasizing about interstellar voyaging long before the technology for exo-planetary detection was developed, but perhaps more likely, it would only occur when the pace of technology development turns the corner of deducing fundamental laws of nature instead of collecting detailed but incohesive insights.  We used the example of exploring our solar system for inspiration of some fictional accounts, and if an alien civilization lives in a system with multiple planets, the period when they are being explored and perhaps colonized might be the time when the meme of interstellar dispersion gets established.

As we know from studies of the evolution of life on Earth, the timescale of evolution is large compared to the interval of time when an intelligent species starts developing technology and gets to asymptotic technology.  So is the timescale for the formation of planets.  Thus the first civilization in the galaxy to develop asymptotic technology will find nobody else there, and few indications that anybody else is likely to evolve anywhere else.  This might become part of the meme after detection systems that can find the signature of life remotely bring back the knowledge that there isn’t any anywhere else.  This first interstellar alien civilization could incorporate that as part of their meme.  “We are alone in the universe and need to spread in order to preserve life.”  Hard to argue with that. 

Latecomers to the galaxy might also develop the meme for interstellar colonization, but when they do, they may encounter the earlier civilizations.  There may be a clash, and the nature of the clash might depend in detail upon the memes that each civilization uses.  One alternative is that the first to disperse might prevent others from arising, either deliberately or by taking over the world on which they might have evolved.  Again, the details of the meme might control their behavior in these situations.  This is something to be discussed separately. 

As a postscript, it is obvious that other types of civilizations could conceivably arise, for example, one based on machine intelligence and robotics that eliminated its biological antecedents, and these other types of civilizations might have completely different ways of self-organizing and different attitudes toward exploration and colonization of the galaxy.  Again, something to be discussed separately.

Tuesday, June 23, 2015

Brakes on Alien Interstellar Expansion

What might slow down the expansion of an interstellar expansion by an alien civilization that had mastered the ability to travel between solar systems?  A simple calculation shows that if they achieved 10% of the speed of light capability, and it takes about as long to establish a civilization on each new planet as it does to get there, they can diffuse outward at about 5% of the speed of light.  This means that crossing the whole galaxy, about 200000 light years, should take 4 million years.  The age of the galaxy is of the order of 10 billion years, so there has been plenty of time for any civilization with the inclination and ability to diffuse to have finished the job. 

If there is a way to diffuse faster than the speed of light, and a civilization masters it, the argument is only stronger.  But what might go the other direction, and act as a brake on interstellar diffusion?  The most obvious one is travel times.  Suppose the mass/payload ratio gets too high as you increase your speed into the percentages of light speed.   If 1% is a limiting factor of the asymptotic technology, diffusion time is up to 40 million years, and 0.1% gives 400 million years, now a substantial portion of the age of the galaxy.  This would certainly serve as a brake.  If 0.1% is the practical limit, and desirable star systems are about 10 light years apart, it would be 10,000 years for each voyage. 

There are several distinct ways in which this type of diffusion might be done, based on what is included on the ship that makes the transit.  One way is to have an inhabited ship, with a crew or at least a group of passengers always present.  Another way is to have the ship autonomous, and the passengers brought into being or unfrozen after the trip concludes.  Reasons for having a crew include the necessity to respond to accidents, or to evade attacks, or simply because the civilization wants to do things that way.  Let us discuss crewed ships first.

This long travel time means that supplies are needed for an extended period, and the ship’s size must include this.  But then there has to be a large enough engine to propel all these supplies, and enough fuel to power the engine for the whole voyage.  To begin with, an interstellar colonization vessel has to be able to contain a large crew, materials to enable the construction of a habitat on the destination planet, and enough startup supplies to last until sustainability is reached, and then some more for a safety factor.  As travel times build up, the problem of materials might get acute.  It goes without saying that the ship is as closed an ecology as possible, but is 100% possible?  If there is a loss as large as 0.1% per year, due to perhaps mixture on an atomic scale, and separation costing too much, a long voyage like 10,000 years means that 10 times as many materials are needed, compared to the amount in circulation.  This recycling loss is added to the sustainability amount, which also needs to include a factor for recycling loss.  Thus, if asymptotic technology only allows a small fraction of light speed, ships grow and grow in size, meaning it is more of a drain on a planet to build and equip one. 

To do some estimating, assume that asymptotic technology has provided the aliens with a 500 year life span.  It could be 5 years with their type of organisms, or it could be 50,000 years, but to understand some tradeoffs, let’s assume 500 years.  For a trip of 100 years at 10% light speed, a group of aliens could be trained for their mission and accomplish it, all within their lifetime.  The ship is essentially the equivalent of an ocean-going vessel on Earth, able to feed and house a crew, but not much more.  For a trip of 10,000 years at 0.1% light speed, the ship has to become a miniature world, with several generations being born and trained, and then serving as crew for their lifetimes, and then dying.  All the infrastructure needed for multiple generations has to be added to the size and weight of the ship. 

Who exactly builds this ship?  On the home world, a civilization has been around for a long time, and can do the construction, but on a newly acquired world, the civilization has to establish itself and increase its numbers to the large amount needed to sustain the construction phase of the ship.  A much larger ship as needed by lower travel speeds would need not only longer construction time, but also longer civilization growth times, before it had the surplus resources necessary to build the next round of space ships.  Thus, travel speed limitations impose a large delay in diffusing, both in the time needed to arrive, but also in the delays needed to construct the next ships to go out.   

The situation gets worse if the maximum travel speed drops another decade, to 0.01% of light speed.  Light speed is 300000 km/sec, and 0.01% of this is 300 km/sec.  For comparison, Earth’s orbital velocity is 30 km/sec, and the sun’s orbital velocity in the galaxy is around 300 km/sec, so if this cannot be achieved, there is no capability of interstellar voyaging.  However, in the most extreme case where the speed limit is 0.01% of light speed, the mass/payload value again takes a large jump, due to recycling losses and generational infrastructure.  It may well be that if asymptotic technology cannot provide 0.1% of light speed, interstellar travel is non-existent.

Engine size controls the acceleration of a ship, and acceleration times burn time provides maximum velocity.  But engine size requirements do not only come from maximum speed.  It is also necessary to make a successful arrival at the destination planet, and this means going into orbit around it.  First, the engine must be able to put the behemoth ship into orbit around the star of the solar system, and then it can gradually work down to where it can transition to planetary orbit.  Once in planetary orbit, it can gradually lower the orbit to wherever the final parking orbit is chosen to be. 

Just to get some numbers, suppose the parking orbit is like the moon’s orbit, and the planet is about the size of Earth.  This provides an orbital velocity of about 1 km/sec, and if the ship has to do the transition in about 10 times the moon’s radius, which is around 300,000 km, to the nearest half an order of magnitude, the ship would have to be able to provide an acceleration of about 1 km/sec in 3,000,000 sec, or essentially 0.3 mm/sec2.  A thousand years is about 30 billion seconds, so this gives a speed of 10,000 km/sec, which is well over 0.1% of light speed.  So having an engine able to maneuver into orbit means that the engine could, if fuel were adequate for 1000 years, get to 0.1% of light speed.  This is another indication that if 0.1% light speed cannot be achieved with asymptotic technology, interstellar diffusion of a civilization is not very likely.

To summarize, there is a very significant tradeoff in cost and time that is controlled by the maximum velocity achievable in an interstellar spaceship, and that if it does not reach 0.1% of light speed, interstellar diffusion is unlikely, and if it does not achieve 1% of light speed, costs go way up to build a slow, multigenerational ship and stock it with enough materials to enable both the transit and the development of sustainable life on the destination planet. 

Under the assumption that the ship is self-propelled, there are three categories.  One is where the ship carries its own propellant and energy source, another where it only carries the energy, and the last where it harvests the energy and propellant as it goes.  A sailing ship is an example of the third and a steamship of the second.  Apollo is an example of the first.  Aircraft are hybrids of the first and second. 

For the first category, if you use your propellant efficiently, you shoot it out in the opposite direction to your destination at light speed, using particles or photons.  To a ballpark estimate, you have to throw out 10% of your total mass to get up to 10% of the speed of light.  The energy you need is proportional to the mass you use for propellant.  Assuming engine mass is proportional to propellant mass flow, the whole ship is roughly proportional in mass and size to the payload mass.  For the second category, collecting propellant has to be done across a larger cross section for a larger ship, but unfortunately, it does not scale up.  Cross-section of a ship goes only as the two-thirds power of the total weight.  This means category two and three ships get harder to design as maximum speed gets lower.  In short, there is no obvious savings of size and cost for slower speeds to compensate for the increase in size and cost caused by making the transition to intergenerational ships, and depending on your choice of propulsion design, it may go the other way.

For autonomous ships, the same arguments may or may not hold.  If there is a transition time when reliability of systems, even using asymptotic technology, degrades, perhaps 1000 years, then instead of multigenerational ships, one would have multiply tandem or self-repairing systems needed.  A multigenerational ship would probably need several times the payload mass of a non-generational one, and a long-term reliable ship might also need several times the payload mass of a short-term reliable one.  Just as the longevity of the individuals of a diffusion alien civilization is not guessable, neither is the period for a transition in reliability requirements.

This means that discussions of interstellar dispersion of an alien species should concentrate on expansion speeds of 0.1% to 10% of the speed of light.  Slower means grave difficulties and faster means some unexpected technology has to be invented.  We all know technology produces surprises all the time, but for the purpose of current-day discussions, this range will serve nicely.

Wednesday, June 17, 2015

Hey, Alien, Are You Guys Predators?

The problem of scary aliens really bugs you.  You are concerned that every alien civilization you stumble over might be planning to take over your home world.  You lie awake at night thinking about whether they are coming tomorrow or not.  So you decide to do something about it.

You go out drinking.  At a local bar in one of your favorite alien worlds, Murt, you sit at the counter and ask the alien next to you, “What do you Murt guys think about being predators?”  The alien turns and looks at you with a smile and says, “That question needs lubrication for a good answer.”  So you grudgingly buy a round of his favorite, and say, “Well?” 

“I think I can answer that, as I’m an average Murt citizen, with the same intelligence and education as all the rest.  We all think the same about that question.  But I have to start with a story.”  First sip break and you wish the stool had a back, because this looked like a long night.  “Right after we figured out technology, about 300,000 years ago, we asked that question.  A bunch of Murt guys got together and volunteered to figure out the answer.  One idea that one of the guys had, and I don’t remember his 12 digit birth order number, was that it would be a lot less boring to be a predator civilization, seeing as how technology had all been figured out and everything was just about as perfect as it could be.  Another one said that it would be a challenge for us Murties, and there weren’t any other ones around.  A third one said that he didn’t have any feelings about eradicating other civilizations as long as it didn’t require a draft.  The fourth one started with an expletive, which I can’t translate because you don’t have the right organ, but then he reminded everyone of Lesson 764, which they had all learned while young.  ‘Lesson 764’, he noted in a stern tone, ‘was about the purpose of a species.’  And he went on about it.”

“’Back before the whole ecosystem was run by the Master Computer, there were species of all different types, all trying to do one thing: Populate.  Lesson 764 noted somebody in the primitive era figured out that there was a big difference between the purpose of an individual of a species and the species itself.’  The others in the group may or may not have remembered that, but they nodded in agreement.  Since we are the only species left, other than ones we made for one reason or another, that probably applies to us.  The Master Computer heard all that of course, and took it from there.  Four guys was enough to get it started, since we all think alike.  Anyway, that’s how Murt started being a predator.”

You have to interrupt and tell him you hadn’t known Murt was a predator, because you never saw anything that looked like something they would use to be a predator, like a spaceship or something like that. 

“I can explain that too, but it will cost you.  By the way, there is a monument to some predatory thing about six blocks from here.  You must have missed it.”  One more round, and he started again.  “Once you have been a predator around locally, and have gotten rid of all the other civilizations in your neighborhood, you take over their worlds.  After that it’s more efficient to let those worlds do the predatory stuff, as they are closer than we are to the next round of places to take over.  Predation is pretty transitory, after all.  Maybe 50,000 years and we had done it all.  Nothing left for us still here on the home world to take over.  It was less boring for a while, but now we are back to living here in a perfect world with everything we need or want.  What a thrill.”

Even you could detect sarcasm in his voice.  Maybe it was time to go home.  If you turned in the other direction and asked the Murtie on the other side the same question, you’d get the same answer.  They do all think alike.  But you wanted to keep talking, and you need another question.

After buying another round, the second Murtie resolved your curiosity.  “Yes, we did run into other predators, but there were more of us.  We eradicated them.  Lost a lot of Murties, but we grew more of them.  That was quick, actually.  All the worlds we have are full of exactly the right number of Murties.”   

Of course, any civilization that had been eradicated wouldn’t have bars and you wouldn’t have visited them.  That probably doesn’t mean anything, though, being just some remembrance of a class you took.  Psychology?

Back home, you aren’t going to sleep any better after these revelations.  You now knew aliens are either predators or prey, and it wasn’t the prey who would be coming around.  

Who Wins in the Galaxy: Attackers or Defenders?

Suppose you envision a contact between two alien civilizations somewhere in our galaxy.  As noted in a previous blog, both should have the same technology development, asymptotic technology.  That means that the weapons, both offensive and defensive, that each could possess would not be different in technology.  One civilization may have more resources, and therefore could have quantitatively more, but they cannot have qualitatively more that the other civilization could possess. 

Let’s also suppose that one of them was a predator, and wanted to boot out the other one from their own home planet, or planets, or world satellite, or moons, or wherever they lived.  Making this supposition is a bit chancy, because the two civilizations would be near identical, as discussed in that very same previous blog.  For the purpose of this blog, let’s assume the first one is a predator for some reason to be determined later, and the other is not.  The first one wants the resources, say the home solar system or systems, of the second.  They want to get rid of the other civilization.  The other civilization will be assumed to have some self-preservation desires, and wants to prevent the first civilization from eradicating it. 

Let’s consider first attacks with explosive devices.  If civilization I amasses enough of them, and can transport them to the home world of civilization II, and then drop them on appropriate points and they go off, civilization II dies off and some time later, civilization I can come and occupy that home world.  That’s the assumed plan of civilization I.  Will it work?  We here on Earth are still pretty close to the caveman era of weaponry, only able to make thermonuclear bombs in the hundred megaton class, but we might assume that civilization I, with a thousand years of more technology, can make them much larger if needed.  If civilization II is living on reasonably small artificial worlds, this might destroy them in a short time, along with civilization II itself.  If civilization II is living on a planet or a moon, on the surface, then these bombs might also do the trick.  If civilization II is living on a planet or a moon, deep under the surface, the bombs would have to be much larger to shatter the infrastructure of civilization II.  Here is the tradeoff: Does making such bombs and transporting them across interstellar space, along with the control equipment, and delivering them precisely have a cost which is more than the planet is worth?  It is hard to see how the bomb cost would not be less than the planet’s worth, as if civilization II is eradiated, civilization I lives there for countless millennia. 

Other means of eradicating civilization II might be tried.  We are familiar with weapons of mass destruction of various kinds other than nuclear bombs, such as lethal contagious viruses.  These would be well understood by the aliens in civilization II, and means of stopping the contagion applied rapidly, as soon as the attack was recognized and the virus diagnosed.  Some sort of cyberattack could be tried, but all of the possible cyberattacks could be just as easily figured out by civilization II and defenses built in to their systems.  It’s hard to imagine what another thousand years of hacking will lead to, but the basic principles of defending a communication and resource transmission architecture should be completely understood, and if the costs of defense are not too great, they could be done.

Mass assault is probably not feasible, as civilization II’s home world will have billions of residents, and being able to drop in enough warriors to kill all of them one by one is likely so expensive that it is not possible.  So, from our caveman perspective, bombs are the thing.

Can civilization II defend itself against such an attack?  First to be considered is the element of surprise.  Can civilization I pull off a surprise attack on civilization II so that civilization II does not know it is going to be attacked until the bombs start detonating? 

Asymptotic technology plays a role here.  Civilization II knows how life originates, and can figure out that there are planets within some radius, maybe a thousand  light years, that could harbor life.  They know the optimal way to build large bombs, how to transport them, how to disguise their approach, and how to detect the approach of the disguised bombs.  They know the exact technology of civilization I and all the possibilities that civilization I might try, because they have the same knowledge.  Both sides can figure out the other’s best strategy.  So, what is the cost of detecting the incoming bombs far enough away so that whatever defensive reaction is best can be done?  Does it sap all the energy of civilization II to protect itself?  Very likely not.  Detection of a swarm of objects coming toward the home planet at a large distance, even if the signatures have been concealed, should be a small cost compared to running the civilization.  Signatures are all those emissions which are detectable, and as we know them, involve electromagnetic emissions from the microwave range up to X-ray.  To reduce those signatures, civilization I will try to make the outer surface of the bombs cold and black, so they neither radiate their own heat signature nor reflect sunlight.  In asymptotic technology, we can expect them to be at the best temperature, that of its background, and completely black.  Civilization II might be watching for transit effects, when one of the bombs obscures the light of a star of the galaxy, so the incoming trajectory would have to be chosen to reduce this possibility.  They would not be large enough to provide gravitational disturbances to other objects in the home solar system of civilization II.  So, detection is possible, but the range is likely to be short, with a warning time of the travel time from nearby, maybe only a few days. 

Given a minimal warning, what options does civilization II have for an active defense?  Active defense involves defeating the attack, as opposed to a passive defense which means absorbing it with reduced damage.  The success of active defense depends on the warning time.  If we assume that the bombs are not braked upon entering the solar system, but are still traveling at interstellar speeds, a fraction of the speed of light, material defense with some sort of projectile is unlikely.  Beam defense with an electromagnetic or particle beam might work, but the difficulty is having enough time for these types of defenses to work.  They involve an integrated effect.  In other words, they do not blow up like an interceptor projectile, but erode the surface of the incoming weapon.  At a good fraction of light speed, there would have to be a tremendous transmitter to make enough erosion of the bombs’ forward surface to destroy it.  Clearly civilization I would make a thick shield there.  Other types of active defenses have similar problems.  So, active defense is not very promising.

Passive defense of some or all of civilization II’s aliens and infrastructure by deep burial is possible.  Shock isolation technology would be at its asymptotic limit, and if the aliens can go deep enough or have a planet with an outer layer that is sufficiently absorbent of shock waves, like sand, they might survive the attack.  However, they would lose communication with anything outside their buried structures, meaning they would be mostly defenseless against any later attacks or an occupation, which might start once the effects of the initial attack abated.  The contest between a buried group of defenders, using only resources obtained from minerals deep within the crust, and a group of occupiers on the surface is an interesting one.  It might come down to growth rates, which would be small for the defenders, having little energy at their disposal, and the occupiers, who have all the resources available on the surface and from the rest of the solar system.  The economic advantage indicates that the defenders would not win over the long run. 

For a first look at the problem of a war between two civilizations with asymptotic technology, it appears that the attackers have the advantage, and are likely to overwhelm the defenders.  This is exactly analogous to our Cold War standoff, and requires us to think of the solution that was found for this threat: deterrence.  If civilization II knew about civilization I, and could build an identical set of attacking weapons, they could threaten civilization I with mutual destruction.  This worked during the Cold War, and perhaps it would work in our current imagined situation. 

In order for deterrence to work, a civilization would need to be able to do two things.  First, they must be able to target their attackers.  In other words, they would need to be able to tell where the home world of civilization I was and be able to send information to their deterrent weapons on where it is and the details they need to attack it.  Second, they must be able to defend their deterrent weapons against being destroyed in the attack of civilization I.  They must also ensure that those weapons are not destroyed shortly after being launched toward civilization I by any devices that civilization I arranges to simultaneously arrive at the home world of civilization II. 

If there are many possibilities for a home world for civilization I, civilization II would have to decide to annihilate all of them for deterrence to work, or to figure out from the attack, during the warning time, which one it was.  For the defense of their deterrent weapons, they would have to have a base for them that was either dependent on concealment for survival, or on being able to survive the attack using passive defense.  With passive defense, digging out is a large problem.  If the weapons are capable of interstellar travel and attack, they would not be particularly small and concealing them or excavating them would be a challenge.  Either way, deterrence is difficult.

There is one saving feature that has not been discussed.  That is reconnaissance.  If civilization II is able to continuously monitor the home worlds of civilization I, they might have much more warning and a much greater ability to deter.  This is a topic worthy of a separate blog.

Asymptotic Technology

In order to attempt to determine some facets of potential alien life on other planets, a particular concept is useful to facilitate discussion.  It is ‘Asymptotic Technology’.  This is the ultimate level of technology. 

It is hard to imagine that technological improvements can go on indefinitely, or that the getting close to the limit will take very long.  The first of these two ideas, that technology itself has fixed limits that cannot be surpassed, comes from the realization that there are natural laws that limit what can be done.  Consider the most obvious of them.  How fast will a spaceship ever be able to go?  Maybe the limit is the speed of light.  Maybe there is some means to surpass it, but that will have a limit as well.  Perhaps the limit comes from the laws of physics, or perhaps it comes from engineering tradeoffs.  Perhaps the limit is different for different particle densities, meaning that intergalactic flight can be faster (or slower) than intragalactic flight.  But whatever the limiting factor is, it is a limit.  The same concept is applicable to all types of technology.  How dense a memory storage device can be made?  Atomic limits should prevail.  How smart an organic brain, per cubic centimeter, can you design?  How efficient a genetic code can be invented, if DNA is not the most efficient?  What energy sources can be tapped for a positive net return of energy?  And so on. 

The point is simply that there are limits, not that we have much of a clue what they will be.  And if there are limits, different alien societies will find the same ones, if they keep pushing their technology.  So, the concept of asymptotic technology is a very valuable and important one for thinking about alien civilizations.  They will all have the same capability in technology.  One might have more resources than another, but technologically, they will be the same, if they have had enough time and have made enough effort to find these limits.

This leads to the second part of the concept. It doesn’t take too long to get to the end of technology development, where a civilization knows everything that there is to know about what it can do with technology.  Obviously there is an immense amount of data about the universe, such as details of all its planets, so knowledge itself is virtually unlimited.  But technological knowledge is not, and there is not all that much of it.  This last point comes from the rate of progress determined here on Earth.  Over a few centuries, we have made great leaps in developing our technology, even though it may still be very primitive compare to asymptotic technology.  This means that the asymptotic limits should be achievable in a matter of millennia, not millions of years.  Millennia are a flash of time in the life of a planet. 

Any civilization that passes through the technology phase and survives for long times afterward, meaning tens, hundreds, or thousands of millennia, is going to have the same technology.  This means that if one civilization were to contact another, they would not be able to trade technology, as both would have the same.  If there was an optimal way to communicate over long interstellar distances, they would both know it, and be using it. 

Technology will also spread to other aspects of society beyond hard science.  It will encompass every part of society.  For example, we will understand how our brains work.  This will lead to an understanding of what makes art impressive, and then we will be able to generate art of whatever kind exists that is maximal in its effect.  So there will be no art to share either.  Both civilizations will have the same capability.

Genetics will be subject to asymptotic technology as well.  We will know how to make organisms do anything we want up to the limits of genetics and biology.  And these limits will be the same for any civilization.  If it is useful to create some type of plant in one civilization, the other will find it useful to do so as well if the environment is the same.  In other words, technology will replace evolution.  Again, one civilization will have nothing to offer to another one that it does not already have. 

In all likelihood, civilizations that come into contact with one another will be in the asymptotic technology stage, and so be almost identical.  Their planets may be different, but if we assume that the aliens live in environments they construct themselves, these will be the same. 

If a civilization in the asymptotic phase were to come into contact with one still in its very short technology exploration phase, the younger one would have absolutely nothing of interest to offer to the older one.  No art, no creatures or plants, no insights about the mind, life itself, or psychology, no inventions, no nothing would be of interest to a society in the asymptotic phase.  There would be virtually no reason whatsoever for any sort of a trade arrangement, even if it turns out that trade over interstellar distances is feasible. 

Thus, benign interstellar contact can be predicted to be virtually nil.  The answer to the Great Filter question posed in an earlier blog is even clearer with this exposition on asymptotic technology.  No advanced civilization has any interest in interstellar communication, trade or tourism.  A society that was in the technology gathering phase might want to speed up its technology development by learning from another older society, but all it does it change the time to reach the asymptotic level.  Whether that is less expensive, considering the costs for interstellar interaction, than simply developing the technology at home, remains to be seen.  Consider also that traveling on a round trip to another civilization’s home only a hundred light years away is likely to take millennia, at least until some faster-than-light technology is developed.  Those millennia might be more than enough to finish off technology exploration at home, so that the return of the explorers with some new technology would be met with the home world already having found it themselves.  All in all, even for the brief length of time that it takes to develop technology, it is likely that interstellar exploration, tourism and commerce are losing propositions and will most likely will never come into existence anywhere in our galaxy.

Sunday, June 7, 2015

Hot Jupiters – A Whodunit

Astronomers who collect exo-planets have noticed there are a lot of hot Jupiters out there among the planets discovered so far.  A hot Jupiter, to get the story going, is a planet around the size of Jupiter orbiting its star at a close distance, well inside the radius of the orbit of our planet Mercury, where things get really hot.  Some say it just a result of the selection process of planetary detection, but, being suspicious by nature, my bet is that somebody did it.  There aren't many clues to go on, but in the best Sherlock Holmes tradition, let’s sleuth out what we can.

Who could have done that?  Well, it’s probably not done by remote control, so that means the likely suspect is the space-faring race that is currently living there or at least colonizing that solar system.  Most likely there is only one such group at any solar system, so there’s not much doubt who did it. 

What’s the motive?  Why would they do that?  Well, what would a space-faring race need?  Three things come to mind immediately.  One is energy.  Another is resources, by which we mean materials of various sorts.  The third is a place to live.  You might get all of them by pushing a Jupiter towards its star.

Lots of people interested in mankind’s future think about where to get energy.  For a few decades, since the discovery that the sun’s energy comes from fusion, there has been the concept that someday mankind would be able to control fusion, other than in hydrogen bombs.  Those who think fusion will not be achievable talk about a modest future, running on solar and wind power, with another few renewables thrown in, after we use up the available fossil fuels.  Solar power is of course derived from fusion.  So is wind power, but it has a more complicated series of transformations before the sun’s photons’ energy gets to the windmill’s turbine.  This concentration on one source of fusion power or another seems to be a bit of monomania.  Gravity is a source of energy as well, but our planet doesn't seem to be using much of it anymore, or at least not so obviously.

When the Earth condensed from the effects of gravity, it got hot, and some of the original heat of condensation is probably still around, although the core‘s temperature is thought to be fission generated.  So geothermal energy might have some gravitational energy in it, but not in any obvious way.  However, moving a planet closer to its star clearly is going to generate a lot of energy.  The star is at the bottom of a deep gravity well.  So, one possible motive for moving a gas giant planet nearer its star might be energy extraction.

Resources can be in various kinds.  One sort is minerals, buried in the rocky core of a planet.  We can dig into our planet very easily, but if there was a tremendous atmosphere on it, stripping off some of it might make mining easier.  If a planet gets close to its star, the atmosphere is going to be affected by the stellar wind, and heated up as well, so some of it might escape by thermal effects.  Bringing it down near its star, and waiting a long, long time, might mean that the rocky core could be eventually mined, perhaps only on the cold side of a tide-locked hot Jupiter, but that could still be a lot of minerals.

Another sort of resources is hydrocarbons.  If you wanted a solar powered hydrocarbon factory to be efficient, you could move the hydrocarbons near to the star.  Jupiter’s atmosphere is full of hydrogen and carbon compounds and other Jupiters might have the same mix.  Solar power is pretty weak near our Jupiter’s orbit, but near Mercury’s orbit it is a lot more potent. 

The third thing a space-faring race might want is a right-sized rocky planet in the habitable zone.  If you have a Jupiter occupying that zone, you need to get rid of it.  Alternatively, your Jupiter, or Jupiters, might not be occupying the habitable zone at all, but nothing else is either.   Maybe you can use the motion of the Jupiter toward the star to bring the planet you like into the right zone. 

It just so happens that the three or four things the space-farers might want to obtain by moving a giant planet in closer to its star are the things we like too.  We have a large part of our (primitive) economy engaged in energy capture and transformation.  Another large part is mining resources out of the ground, and hydrocarbon manufacturing based on fossil fuel inputs is also large.  And developing new housing and entire cities takes up another big chunk of our economy.  So, if the space-farers are just like us, only more advanced, they are probably doing the same things we do on a larger scale.

So we know who it might be, and the motive for doing it, but we don’t know how.  There hasn’t been much theoretical work on the engineering of moving planets around in a foreign solar system, so we can’t cite a series of possibilities.  But it probably is being done as cheaply as possible.  Having a large planet fly by the target Jupiter might, if the orbits were cleverly chosen, gradually push it inward toward the star.  The large planet might be put into the right orbit by using a smaller planet, which in turn is being altered by a yet smaller one, down to where we get to an asteroid, which is probably easy to move around by an advanced race.  They would certainly be able to observe the existing orbits, predict them with as much precision as needed, and predict how they would change as well.  This would be a very cheap way to move a Jupiter.

Thus, the whodunit is over.  We have some ideas on who, why and how.  Details like ‘when’, for processes which might take a million years, are not as important as they are to domestic crime-solvers. 

Some people hunt for alien races by listening for some sort of radio signals.  Perhaps hot Jupiters are a better clue.  So, instead of wondering if there are any alien folks out there in the galaxy, we should examine closely what might be the artifacts of their engineering.  This changes the perspective we might have on aliens in general.  The problem of the Great Filter, as it is called, which prevents aliens from visiting Earth is a vastly different problem if we deduce that many of the nearby stellar systems are inhabited or colonized, or at least have been visited in the past when the engineering of orbits was done.  It may well be that the Great Filter doesn’t exist, and the lack of aliens here is simply a matter of timing.  Perhaps we should watch how the orbit of our own Jupiter is changing over very long periods.