What could restrain post-singularity societies from spreading across the Galaxy?

Question

Imagine a world in which technology we would probably call "technological singularity" is possible and already happened on few places of the galaxy. By the singularity I do not mean that anything is possible, but rather that original biological species transform themselves into extremely highly intelligent computer programs with big amount of control of their environment, and they completely transcend their biological nature. The post-singularity societies might rebuild planets to giant computers or even create Matrioshka brains, since the main scarce resources are computer time and memory. It would be relatively easy for such civilization to send spaceships that would transform all solar systems in our galaxy into computers and utilize them. It would be even easy for a small splinter faction inside such civilization, unless the "official forces" actively prevent it. The motivation is simply a lot of resources and freedom to gain.

My question is: Are there plausible reasons that would prevent it and keep the civilizations bound to their home star systems?

If there is such, the reason should be strong and valid for all such civilizations. If nine out of ten civilizations decide not to spread, and one does, the galaxy will still be transformed.

Answer 1

Very good question. Nothing can prevent a patient post-singularity civilization to spread all over the galaxy. Milky Way is around 100K LY across, so even at a slow 10% speed of light spreading (to allow rebuild/refuel spaceship at each new planet reached), most of the Galaxy should be visited in mere 1 million years. Compared with 4 billion years from the emergence of life to the present, one million years is nothing. So it should already have happened. Even at mere 1% of the speed of light, it takes a mere 10 million years.

This is the real problem. Where is everybody? Fermi paradox.

Even if most post-singularity "persons" were interested only in local entertainment, one out of million will be curious enough to leave the "hive". And will have enough resources to learn, travel, spread, and multiply. In few million years, a new race of "space explorers" would evolve, with curiosity and itch to take over the galaxy, even if they don't need the resources. Just do it for the heck of it. If it is possible to do it, someone will do it, given enough time. Why not?

So there must be something preventing civilization like ours successfully transforming into the post-singularity phase. And that unknown danger is something we should worry about.

There are plenty of planets compatible with life, old enough for life to emerge. Plenty of time to evolve all the way to Technological Singularity. Plenty of time for such singularity civilization to settle all over the galaxy. Time is not a problem - something else is.

Most likely, advanced civilization (like ours) commit suicide before reaching singularity either by grey goo, green goo, or ecological catastrophe. (which is also one of possible answers to Fermi Paradox). After singularity, there is nothing to stop them.

Few very good reasons to get out of your solar system:

• In about 500-800 million years, our Sun will start growing to be a red giant, making Earth uninhabitable.
• And even before that, some random asteroid or other calamity can damage our planet. The Yellowstone super-volcano erupts every some 600 KY. Asteroids able to extinguish dinosaurs may struck every 60 MY or so.
• Even if you are able to defend your civilization from attack of another advanced civilization, basic strategy is "defense in depth", and you need sentry outposts far away from home planet, give advanced warning to have time for mobilization of the necessary resources.
• Even if that another civilization is not inherently trying to eliminate "ours", you still need to have a defense in depth to have time to convey to them information that you exist and think. It is about 200 MY between ants and us. Imagine how hard would be to persuade younger partner (us like ants) some more advanced civilization to notice us and care enough to not extinguish our suns. The only answer is "defense in depth".

For self-preservation, even post-singularity civilizations need to settle around other suns.

Only reason to NOT settle around other suns (and eventually settle all over galaxy) is that some event prevented civilization to reach such advanced stage to be able to do it. And that should worry us.

@Peter LeFanu Lumsdaine answer has plausible suggestion of early singularity civilization imposing non-proliferation on any other later singularity civilizations.

But even such "protector of wilderness" civilization would still be required to spread all over Galaxy and impose rules on other civilizations by "missionaries" and "park rangers". And it just escalates "defense in depth" over neighboring galaxies - because by this you voluntary limit your resources to just small part of your galaxy, and other competing civilizations from other galaxies might have more resources.

Compared to that, @Mike Nichols answer requires that every of the hundreds/thousands of civilizations reaching singularity will apply similar self-limits and will stop any spreading. That is just not plausible - even worse, that is naive. Why would any civilization take such risk on behavior of hundreds of unknown competitors? Why take chances, if you have resources to enforce the rules?

See also: Motivations for interstellar colonizations

Answer 2

If your beings have completely transcended all biological forms and are now incredibly powerful computers, why would they want to go to other systems? They don't need any more space, or energy, or materials. They are self-sufficient computers. There is no biological urge to reproduce or procreate. There is nothing to explore that they can't simply observe with telescopes and compute with their awesome minds. Yeah, they could turn the rest of the universe into machines like themselves, but what's the point? I think the best reason for the universe to not be consumed by uber-entities is that there is simply no good reason to them to do so.

Answer 3

Are there plausible reasons that would prevent it and keep the civilizations bound to their home star systems?

Reason 1
Space is huge. Most humans, because of the way we are taught, don't properly perceive the size of space. If you have ever seen the earth and the sun depicted on the same page, you are seeing an exaggeration of the size of earth or the distance between earth and the sun. To properly represent our solar system with the sun the size of a grapefruit, Pluto would be a microscopic peiece of dust some 30 yards off in the distance. That we picture pluto in our diagrams on the same page as the sun, or even as a 3d model is a tribute to our distorted sense of space. So number 1 reason...space is HUGE! and we are badly incapable of envisioning how huge it truly is in our heads

It would be relatively easy for such civilization to send spaceships that would transform all solar systems in our galaxy into computers and utilize them.

I also think you are badly interpreting the size of the galaxy with this statement...even at light speed, these systems are far enough apart that it takes decades and millennium to travel between the two. Remember the light from the stars you are seeing is a distant vision into the past state of these stars. At light speed, it's a good 120'000 years to travel from one end of the system to the other, and we are talking of upwards of 300 billion stars in simply the milky way alone (billion being another concept that no human can rightly visualize). Lets say you drew the entire milky-way on a 10 meter by 10 meter map...our solar system will not be visible to the human eye on this map. And the milky way is a surprisingly small galaxy in the grand scheme of things.

Reason 2 - different planets in different area's of the galaxy likely have a much different composition and bring with it a series of unexpected and near lethal challenges. In forming, the milky way likely has a compositional change from the center to the edges not unlike the solar system has. Who's to say rock worlds are even feasible in the inner bands of the milky-way? What challenges will each new system bring, and will it even be worth the invested resources to 'colonize' the new systems?

Reason 3 - Interstellar travel might be far more complex than what we think. The Sun generates an amazing magnetic field that prevents solar winds from reaching it...these solar winds can hold protons flying at 99.99999999% the speed of light, striking objects with the force of a 70 mph baseball on an atomic scale. We get to see occasional glimpses of this as these protons will occasionally send neutrons flying at us at incredible speeds. This might make interstellar travel a much more arduous task than what it might seem currently. Who knows what effect dark matter may hold for interstellar travelers

Reason 4 - why? I know that's a bit abstract, but in the end...why? What does anything truly have to gain by doing this? Is it that dies with the most toys syndrome? Is freedom of infinite expansion until the universe fades really meaningful? A philosophers dream question - but what if the reason another intelligent life form has never visited us is simply because a higher intelligence ultimately realizes the never will be an answer to the question 'why?'

Reason 5 - eventual destruction. Suns die and are reborn, no planet is forever. The milky way is going to collide with the Andromeda galaxy eventually. And whatever that mass becomes will collide with another galaxy eventually. No matter what you colonize, it's going to change, it's going to be destroyed, and it's going to start anew.

added:

Reason 6 - Time distortion. It might not have been so many billions of years passing at different points of the galaxy and there may be places that have seen only hundred of millions of years next to ours. A bit more theoretical, but at what speed must something be moving in order to be frozen in time?

added again:

Reason 7 - Threat of splintering. In human history, games, and story lines there are many examples of the colonized turning upon those that created the colonies. The US vs Great Britain is the obvious example on Earth, but there are several fantasy story lines of Mars colonists revolting from Earth rule. There are also fictional story lines of entire races that revolted from their creators (Yor Singularity in Galactic Civ). With communication difficulties over large distances, what is to say newly colonized worlds do not try to conqueror those that colonized them? How does a singularity mitigate the risk of it's extended colonies becoming the primary threat of it's own existence?

Answer 4

Mike Nichols’ answer suggests “lack of motivation”, or (differently viewed) “change of morality” as a possible reason. His version of the scenario seems a little bit of a stretch to me, since (as comments on the answer point out) it would require that all post-singularity civilisations would undergo this evolution of morality, with not a single dissenting exception.

A variation of this seems perhaps more plausible. If one post-singularity culture — perhaps the first, or perhaps just a sufficiently powerful early one — happens to have the right set of ethics, they could set up and impose a moratorium on others, preventing anyone from spreading very far (while also choosing not to spread themselves). It could be because they particularly value diversity, or solitude, or some kind of wilderness conservationism ethic — any number of reasons.

Of course, in some sense this would still be colonisation. They would have to distribute some representatives of themselves or their tech around the galaxy to enforce the “peace”. But the spreading they did could be much, much less obtrusive than any kind of full colonisation/expansion. Imagine them preserving most of the galaxy the way we preserve wilderness areas in national parks. There’s just enough ranger presence that if you try to build up too much yourself, they’ll notice you, come along, tell you the rules, and impress you with their power to (if necessary) enforce them. But most of the time, the presence is so distant and non-interventionist that you still are, to all intents and purposes, in a genuine empty wilderness.

Answer 5

Are there plausible reasons that would prevent it and keep the civilizations bound to their home star systems?

Maybe you are asking the wrong question. Other answers have mentioned the Fermi Paradox. That paradox comes from a different question. Where is everybody? Your question makes an assumption that you might not have realized. You assume that if they aren't "here" they must still be at "home".

That isn't necessarily true. I'm going to making the assumption that you meant the question to be Given a technological singularity that would let a civilization spread across the galaxy, where is everybody?

One thing to keep in mind, is that a singularity, by definition, is incomprehensible to us. The singularity uses super-human AIs to do things we literally cannot. A singularity is going to be more than just mind uploading. If, as you say, they've 'completely transcend their biological nature', perhaps that's why they haven't colonized the galaxy.

In other words, the singularity causes them to leave and go somewhere else.

Maybe they've ascended. Like the Ancients in Stargate, or the Q. They've lost their biological and corporeal nature and live in the quantum foam. They aren't going around and colonizing the galaxy for resources because mundane things like matter, anti-matter, and energy are below them. They don't even consider those things resources anymore. They've moved beyond that.

Maybe the singularity occurs because they discover higher dimensional math. Instead of colonizing the galaxy, they are colonizing their home system an infinite amount of times in parallel universes.

Answer 6

I imagine most posters here will be familiar with the works of Iain M Banks, and his series of novels about 'The Culture', and the civilisation(s) he describes - extended post-singularity, post scarcity societies, where sentient beings co-exist with highly evolved AI (such that the AI has been almost transcended to become pure I).

Several of the books address the issue of 'Why'/'Why not', morality, and motivation. The title 'Excession', particularly.

en.wikipedia.org/wiki/The_Culture

www.iain-banks.net/sciencefiction

I regret I do not have sufficient rep to post this as a comment, rather than an answer. I don't feel it fulfils the criteria for an answer, but wanted to contribute.

Answer 7

I just finished reading Charles Stross' Accelerando (like, thirty minutes ago), and he does a great job exploring why post-singularity Matrioshka-brain civilizations might not tend to leave their home star.

The scale of the book doesn't begin to touch what happens when the sun goes out, but his central premise (spoilers!) is that wide-scale conversion of "dumb" to "thinking" mass only begins in earnest once a significant portion of the population exists in mind-uploaded, rather than physical form: it's to solve a population crunch, not just for the raw computing power.

By the time the solar system has been mostly computerized, with human or human-like intelligences doing their thing in cyberspace, proximity to the densest resources -- computer time and memory, as you mentioned, but especially one you didn't, bandwidth -- is most highly desired, and humanity as a whole is too unwieldy to move en masse. Even a wormhole-sized network connection isn't enough to squeeze the population through.

These intelligent hunks of computerized matter cluster around their primary energy source, and, being able to simulate a whole host of realities, lose the adventurous spark (and most of the advantages) of going out to find new worlds.

For plot purposes, the nail is driven into the coffin when the course of human cognitive augmentation turns them into something else entirely, and these ruthlessly efficient, market-driven nonhuman superintelligences succeed, then cannibalize their originators as a huge leap up on the food chain, and by then are stuck where they are for good.

It's a good read.

Answer 8

Even if technically possible, space travel is expensive.

In a post-singularity society, energy and mass can be highly efficiently used to generate their best approximation of computronium -- specialized states of matter that compute highly efficiently.

To travel over interstellar distances, you need a lot of energy. Energy that would otherwise be sufficient to generate a rather huge amount of computation. Imagine if our solar system had 10^9 planets like Earth, all fully populated. And in order to send 3 people to a nearby star, we'd have to destroy 10% of them and kill all the people on them.

In the long run, such a probe would result in a larger total "civilization". But with bandwidth restrictions of interstellar communications, those 3 people would be sent off, and would only arrive the equivalent of millions of years later (faster time scale from high clock speed), with the ability to send single bit of data every thousand years (again, scaled based on intelligence of us vs them, and how much they are used to communicating). So even once they are there, they are going to be sending messages back to a really alien society, and there isn't enough bandwidth to discuss what is going on (at the level the civilization is used to), let alone coordinate.

So now you have a society that destroyed 10% of its population, and in exchange has created a colony that can not meaningfully interact back with them.

The upside might be hard to see.

Those 3 colonists arrive in a barren wasteland. Suppose they can manage 0.1% economic and population growth per year until they hit the equivalent of 10^20 people (they are building an economic system from scratch). So it takes them all of 50,000 years to reach the previous point of a civilized star system. At which point they could go and kill off 10% of their society (or prevent them from ever existing) and launch another star wisp.

Repeated, this does colonize the galaxy (10 ly every 50k y times 100k ly is only half a billion years. If the trips take another 50k years, that only doubles things) (so long as your star wisp production per star wisp launch stays detectably greater than 1, the limit is distance: the wave of colonists ends up being limited by the geometry of the milky wa more than anything).

So the capabilities of a post-singularity society might be great, but the other things they can do with those resources is equally great.

And it might be the case that the post-singularity society can manage a greater growth rate locally in whatever they care about (computational efficiency, say) than they could by the (basically linear or quadratic) growth rate you'd gain from galactic colonization.

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Then there is the optimists case.

A sufficiently advanced technology is indistinguishable from nature.

Wrap stars in light-year deep computronium foam, and the surface temperature of the foam is...

Sun outputs e26.5 J/second.

A sphere of radius 2 light years has 50 square light year surface area. The sun emits about 1 degree kelvin over that radius. That is warmer than black body radiation: so a much smaller sphere can be used, which would place such a matryoshka sphere as being in homeostasis with the microwave background radiation. (The real problem is that it might also occlude other stars and thus be noticed)

Move such systems out of the main part of the galaxy (the better to avoid super novas and the like). Wrap starlight around yourself to finish the invisibility job. And now you have invisible, massive civilization that looks a lot like dark matter.

Leave some of the galaxy alone as a preserve.

Noise is waste. Presume an efficient civilization, and you cannot hear them.

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Or, transcend. What if it is easier and more efficient to move computronium into more traditional dark matter than it is to visit another star?

Answer 9

The biggest preventative factor of a civilization such as the one you describe is motivation. If a post-singularity civilization is content with what they have, what their experiences are, etc. then there is no reason for them to seek anything else. They have nothing to drive them from their little bubble.

Other factors could weigh in (lack of faster than light travel coupled with resource limitations, physical limits, risk, even cosmic radiation affecting hard drives), but the civilizations implied by your question would, effectively, have infinite time, which means time to mitigate or even eliminate any external limiting factor. Even political influences could eventually be waited out or gotten around eventually. There would have to be some variety of civilization wide contentment.

Note, this would have to be quite different than stagnation. There would still have to be technological growth and evolution, they would just have to look internally ("I must protect my little slice of heaven) rather than externally ("I want their little slice of heaven). It would also imply a lack of scarcity.

Answer 10

lifespan, social structure, speed of reproduction, or lack of fast travel (even 10x light speed is slow when you're talking interstellar distances).

A hive society could not survive a trip to another star system if they couldn't take enough of a group with them (basically an entire culture, think transplanting bee colonies, this would be similar).
A species that reproduces very slowly, especially if it also depends on larger social groups for its survival, is at an even greater disadvantage, obviously.
A short lived species may not have members that live long enough to make the trip and settle at their new home AND raise a new generation before they die.

A species that reproduces very slowly may not even be interested in expansion, as they may quite likely never feel population pressure, which in most species is the main reason to seek new areas to live in.

Answer 11

Like most things, what would be the driving force to spread across the cosmos, and what are the limiting factors preventing such a thing?

If humanity figured out a way for a 'reasonable' price to travel to the nearest couple star systems in 3-6 months, we would do it just because we could. Humans are curious and get bored easily, so I would think that after a singularity that spreading across the solar system would be are first jump making a ring of settlements around the sun but that would only occupy us for a little while as we get better at it and use space construction techniques to build impressive interstellar ships.

The more of this we have before the singularity the faster and more likely we would be to flee the solar system to explore strange new worlds to seek out new life and new civilizations...

However, something that could certainly prevent that is if we enjoy very long life expediencies and we become a society that is more interested in our pleasures and entertainments, everyone is taken care of and no one needs. If everyone is satisfied they will have very little reason to want to risk their lives on long dangerous journeys with no guarantees of survival or return on investment. Need and ambition are the two driving forces of humanity and if we lose one or both we'll be more like the humans in Wall-E, or similar predicament.

Answer 12

We could restrain the absolute number of post-singularity beings by designing them to require a particular rare element to survive. Each time a being reproduces, that resource is split between it and its offspring. Over generations a point would be reached in which beings did not have enough of the element to reproduce with.

Two caveats:

1. This would only limit the number of beings, not their geographic footprint.
2. Caches of the rare elements could be found in other places in the solar system, or the being could figure out a way to copy/conserve the resource.

I'd love to hear any ideas that could solve the second caveat -- what could serve as the non-replenishable resource?

Answer 13

"Plausible technological singularity" is to me a contradiction in terms. The best my imagination can do with it, without throwing away what I think I know about computers, technology, brains and consciousness, is to imagine that a civilization deludes itself into thinking it makes sense to favor a giant self-sustaining computer/machine system over its own biological existence. The people would need to have dissociated from their embodied experience, or to have deluded themselves that it would persist in a machine, or otherwise that this would be a desirable move. They claim to transcend and incorporate all, but fail to incorporate much actual wisdom, and align with imperialist/industrial conquest ideas. I can imagine that happening, and conclude that the result would be a dangerous AI machine system which probably considered itself superior to other life forms, and would probably behave itself like the Borg, though probably without the powers given to the Borg by Star Trek fantasy technology.

The main things I think would stop such a "singularity" system from expanding out of its own solar system, are practicality issues.

• Travel to other stars requires more technological handwavium.

• I also think that in reality, even if a society decided to die off in favor of such a machine system, I expect that such a system would begin to malfunction without any deluded biologicals to keep it on track with its perverted/wrong ideas about how it makes sense to build such a machine system. Without deluded biologicals, I think the "intelligent" computer system, which I would expect to have been programmed to "evolve" ideas and change its own programming, would sooner or later (probably sooner) get "interested" in logical computations which had less and less to do with the (ultimately illogical) delusions of their biological creators, and tend to do unpredictable odd things rather than trying to win some juvenile galactic conquest to maximize CPU cycles, because that is a fundamentally BS idea.

• The idea of needing a star's (let alone a galaxy's) energy to harness as much power as possible because the singularity has so much to think about, seems very silly to me. I think the matrioshka brain is projection of Robert Bradbury's unconscious knowledge that there really would not be infinite interesting things for a giant AI to calculate about, or that it would be worthwhile to try.

• That is, if you posit that it is possible to build an intelligent evolving computer intelligence, then I would expect it to deduce how silly and pointless the exercise of galactic conquest by itself would be, as well as the idea of manufacturing star-scale computing machines. If it doesn't deduce that, then I'd say it has a fundamental flaw.

However, overall, I'd say it were quite possible to build a flawed machine system that would be programmed to go around replicating itself, and this system might well be programmed to try to take over the galaxy. But I don't think even if all of an entire galaxy were turned into a logical computer system, that it would ever conclude that a singularity transcending a biological species would make any real sense.

Answer 14

If speed of light is a real constraint, then the problem might be isolation.

Leaving your civilization to explore, effectively means you will be cut-off from your civilization.... forever. It would be worse than choosing to use DOS, forever. Singularity civilization will be constantly accelerating, if you get off the train, you will never catch up to it.

You would also be cutoff from communities (Goodbye, SE & wikipedia), help (who's out there doing tech support for DOS users?), family (who choose not to go Amish with you), celebrities & culture. That may be a tough pill to swallow. Especially if biological family (vs. self-chosen family - who will have less interest in coming with you, since divorce and ending of friendship is much more common) continues to break down as it currently is in Western Society.

Answer 15

Civilisation

The answer is, in my view, in your premise - they're civilisations. Unless you presume FTL, separate worlds are really, really separated. Even lightspeed communication between solar systems is going to take years and will likely suffer from terrible bandwidth. The post-singularity AIs are going to stick around their home system because that's where the other AIs are and where they communicate and commerce and interact and whatever else they want.

So while they may colonise a number of nearby star systems as their civilisation grows big enough to 'bud off' new large colonies in different star systems, the pull of remaining within a large, vibrant community will prevent them for spreading rapidly through the galaxy.

Answer 16

I disagree with those who claim that nothing could stop the spread. I could see many possibilities that would prevent it.

First, motivation. There needs to be a reason for it to spread. The cost of spreading would have to be outweighed by the advantage of spreading. In a singularity situation, this may not be the case. While the capacity to spread may very well exist, that does not necessarily lead to that capacity being used. According to the Cosmological Principle, the universe is consistent over large scales. Once a machine based intelligence is able to learn everything it can (presuming acquiring new knowledge is a motivator for it) over a 'large scale', there would be very little benefit in spreading further.

Second, fear... of a sort. There are no concrete indications that the limitations to understanding that we have discovered will be able to be overcome by a machine-based intelligence... in fact, there is pretty solid argument that they never could be. I am talking about the fundamental limits on mathematics from being capable of predicting systems with chaotic behavior. A conservative machine-based intelligence which puts avoiding threats to its own continued operation as its primary motivator would be hesitant to extend itself rapidly because it would quickly become incapable of predicting even its own actions. Assuming it has some level of 'acceptable risk', once it realizes this fundamental limitation to its ability to evaluate the consequences of its own actions, it will likely become very conservative.

Third, time management. While machine-based intelligences would seem extremely fast to us, performing actions would still take time. Transfer of information within the organism would still be limited by the speed of light at the very least. This would slow it down the further it spreads itself. As it acquires new things to study, or new regions to gather data from, performing those tasks would take time and transferring the information throughout the system would also take time.

In short, there are fundamental limitations on understanding and information processing that we've discovered and good reason to think that these limitations can not be overcome by a machine intelligence. Many of them could result in an intelligence restricting its own spread.

Answer 17

Perhaps we are simply projecting our own misunderstanding of the universe and our limited goals upon beings beyond our comprehension. Our grasp of the goals and means of action of entities many orders of magnitude beyond us is tenuous at best.

Just like a hunter-gatherer asked about a terrible weapon would imagine a giant or very sharp axe, or a very precise arrow, but could not possibly even conceive of something like a nuclear explosive, so is our imagination limited by our technology and primitive culture.

More appealing destinations. Perhaps a post-singularity society will simply find it easier to travel to parallel dimensions, tap into nearby universes, assault Heaven (or Hell), or Hal only knows what else.

More subtle forms of colonization. Or perhaps they will simply transcend physical form, making the question pointless. Who knows what civilizations might be embedded into what we in our ignorance call the Higgs field, for example. Perhaps the Electroweak breakdown into electromagnetic and weak forces was an epochal and universe-wide civil war.

Answer 18

One of the primary goals of any form of life is that of continuing to exist. Perhaps post-singularity societies (or even pre-singularity) discover some sort of fundamental instability in our universe, and rather than waste time and resources spreading into something that will eventually be lost, they devote all resources to moving into a more stable universe.

I'm sure this has been explored in science fiction already, I just can't remember where I've seen it.

Answer 19

There's been much discussion of the Great Filter already, but I don't think we can logically say the only answer is an impending apocalypse. We can accept that post-singularity (or whatever, really-really-advanced) societies are fragile- they can be whatever-color-goo'd, or destroyed by nuclear holocaust, or computer viruses, or who knows what else. So even if a society does make it to an interstellar-colonization phase, those colonies may themselves die out in time.

We get a model more similar to the spread of disease than the spread of a fire. If a typical colonized solar system doesn't emit more than one group of colonists before it itself ceases to support life, then eventually (over cosmologically-short time periods, even) the interstellar civilization will die out, in much the same way as a virus will eventually die out in a well-kept human city. So we don't require all advanced societies to die out before they colonize other stars- only for interstellar colonization to be reasonably rare (for which there are good arguments) and for societies to die out eventually (good arguments for that, too.)

Which makes the Great Filter idea a bit less terrifying (but not enough that I don't shiver every time they start up the LHC.)

Answer 20

I can't imagine there would be any constraints on such entities, and Paul Davies thinks post-biological sentients will be the the rule, not the exception.

I think it very likely – in fact inevitable – that biological intelligence is only a transitory phenomenon, a fleeting phase in the evolution of the universe. If we ever encounter extraterrestrial intelligence, I believe it is overwhelmingly likely to be post-biological in nature.

How would such entities breed or reproduce?

A copy is just that, like playing chess in a mirror. Better to replicate the process from scratch, find or create a biological species and tweak them to sentience, then let them create their own SI (Synthetic Intellects). In this way you have a brand new SI unique and reflecting its biological progenitors.

We may just be the factory workers, not the finished product