I think we should explore, not colonize. And the best emissaries may be robots to start with.
There are many warnings about the dangers of von Neumann probes. I think it can be done safely. But with great care.
Instead of a "general purpose" machine of science fiction able to make almost anything, the safest thing is to, e.g., design it so it is a reasonably simple machine, and just makes exact copies of itself, no evolution, and with reasonably tightly conditioned responses to situations - with fair amount of autonomy but also reasonably predictable.
After experience with those you might be able to tackle the much more difficult problem of a self replicator able to behave differently in different situations in a more fluid way. And as for evolving self replicators - I think that would be a total No No unless you really had a very clear idea of what you are doing, some advanced understanding we don't have yet.
But - self replicating human explorers of the galaxy are equally scary I think :). Not often said. But by the time they are a thousand light years away - we have no idea what they are doing - could be making von Neumann machines, cyborgs, could be creating new species, could be doing things that are unbelievably stupid according to us but that make sense to them, could be that they are "de-evolving" to creatures with intelligence of a child but vast powers.
We wouldn't know until a thousand years later - by which time there could be almost anything headed our way from the colony. Say, a cloud of von neumann machines designed to turn all star systems into dyson spheres demolishing any planets in the process - someone thought that was a cool idea or it arose out of a von Neumann machine programmed to evolve and solve a problem and that was its solution.
Could be nanobe sized machines, trillions of them, traveling at close to the speed of light, so gets to us before we even know about them, dig into the Oort cloud and make copies of themselves ready for the next step whatever it is, cryptic with technology way advanced ahead of us by many centuries, designed to hide and destroy themselves imperceptibly if discovered so that even when you examine the comets they have burrowed into they just seem like meteoritic dust (say), until suddenly when there are enough of them, they all come to life and do whatever they do next.
Just an example.
Or could be an army of cyborgs, or could be any of the "Alien monsters" of science fiction - only slightly evolved beyond us.
That's my preferred explanation of the Fermi paradox - that sensible ETIs are just as careful about self replicating copies of themselves as they are about Von Neumann machines. And that we will be too when the time comes.
So then - maybe eventually they do colonize the galaxy but if so in subtle careful ways to avoid these problems so probably also with low populations over the entire galaxy.
Or whatever their solution is, if they did it, it clearly is an approach that leads to minimal modification of the galaxy and a hard to detect presence because when we look at the galaxy in our telescopes - as far as we can see it seems totally unmodified and in its natural state. And we may make the same decision also when the time comes.
Where it is no problem to explore the galaxy if you don't colonize. If there were a few million ETI individuals or families or small settlements that tour the galaxy - even if, say, they have immensely long lives of millions of years and touring the galaxy is something every ETI does as a youngster of one or two million years - and there are millions of these ETIs exploring the galaxy right now - so long as they don't colonize and replicate anywhere but return home when finished - they would leave almost no trace of their presence and the nearest would be likely to be light years away.
Leaving a colony of humans somewhere with interstellar travel and colonization capabilities, without forethought about what the implications would be, might be considered as similar to launching an unregulated von Neumann machine, or setting off a nuclear explosion in a crowded city, something that sensible ETIs just would never do. Unthinkable. Because you can see what the potential consequences would be.
I think in the future that may well become unthinkable to almost any advanced ETI. And those that don't think that way, are so reckless, they destroy themselves long before they can be a nuisance to the galaxy - at least - destroy their space faring capabilities, and keep destroying them every time they try to colonize in space - until they become more forward looking.
Because the first space colonies will be unbelievably delicate and easily destroyed. Because if you have space colonies, you have the technology to propel things at tens of kilometers per second. Even an accident at that velocity would totally destroy most ideas for space colonies with a direct hit right away. And deliberate warfare would end up with everyone dead.
So - we need to move forward in some way to a future where we don't do things like that. Otherwise we will never explore the galaxy. And if we are as far seeing as that - then I think we will also choose to explore the galaxy robotically - or if we send humans at all - as explorers that wouldn't think of setting up new colonies until we have thoroughly worked out a way to do that that avoids these issues of unrestricted replication of humans and whatever entities they might create.
We haven't encountered these problems in such an extreme way on the Earth because the whole Earth as soon as it got highly technological was already interconnected, to such an extent that there is no chance at all that one of the countries is more than a few years ahead of any of the others. And so far no possibility of creating self replicators. And if some strange philosophy develops, or viewpoint or approach, the whole world learns about it.
But space colonies could easily be thousands of years ahead of each other. And strange ideas - but not only that - even beings that are independently evolved, and machines, and machine / biology hybrids, and all sorts of things could evolve and they could be hazards to ourselves, to each other and to any other extra-terrestrials out there.
Either we are the first ETIs in our galaxy to have the potential to colonize it - if so it is up to us to find out what to do and to set a good example for the future. And that would suggest we take extreme care because we have no-one else to learn to and tell us what the pitfalls are (except possibly in other galaxies).
Or else - there are other ETIs here already, if so it would be an extraordinary coincidence if they evolved the same time as us, so they would be likely to be a millions, or more likely billions of years old civilization. If so hopefully we detect them eventually and learn from them what to do and what works and what doesn't or is dangerous to do.
If unsure, robots are safest, I mean simple ones, not able to evolve especially, and with limited autonomy. They can be programmed to self destruct. They can go into dormancy for millions of years - if they find an uninteresting solar system say, just leave a few sentinels and go to sleep. They can be programmed safely to visit every star in the galaxy. They can be sterilized so that they don't bring Earth microbes to ET planets.
Safest way to make them would be - non evolving, not "all purpose" machines but perhaps e.g. only designed to be able to reproduce using nickel iron meteorites + silicon, water - some simple machines that let them take the ingredients from a few meteorites to build copies. Only want one or two per solar system. And - each one can create, say, ten copies, but there is a maximum number of generations, say ten. So no chance that through flawed copying they "evolve" anyway. If the copy is not perfect, it destroys itself.
Then - also make them depend on an external signal, something they can't create themselves, and that any ETI can't either, if you can. If they don't get this signal (perhaps based on trapdoor prime ciphers??) say every century or whatever, for an interstellar spaceship (or every year for machines within a system) then they go to sleep or destroy themselves.
If ETIs try to reprogram them, they self destruct. So no other creatures can take them over and make them into unrestricted evolving self replicators.
Something like that. Details to be worked out. But if completely safe, then you could just send out one of these probes into our asteroid belt. It makes ten copies that it sends to the ten nearest stars. Those on arrival make ten more (and start broadcasting findings back to Earth). Those make ten more again and so on. Before long all the nearest stars have them and eventually entire galaxy does. But this process of replication comes to a complete halt after ten generations by which time every star in the galaxy has one of those machines in its system.
Then when they encounter an interesting system, say one with habitable planets, they make more spaceships to explore those systems and tell us what is there.
I'd see that as a possible first phase, done with great care and forethought about possible consequences, so this is just a very preliminary draft idea.
Whether humans colonize or settle or explore - that's a decision for much later once we have a much better understanding of our galaxy and also, hopefully, have managed to develop a little beyond those potentially self destructive approaches to exploration of the galaxy. How exactly that happens remains to be discovered.
And in our solar system - if the first space colonies are based around settlement and exploration - like the ones in Antarctica - I think that is the way ahead. Not push for colonization no matter what. But let it happen naturally where colonies are needed for some purpose. Because we don't need to do a backup of the Earth - that's in some of my other answers here, there are no dangers that would not be better solved by having your backups on Earth not for the next few tens or probably hundreds of million years anyway.
So there is no great rush. Our Earth, no matter what happens in the next few million years (timescale over which new mammal species evolve - so that is a huge future timescale), surely will remain the most habitable place in the solar system for humans.
As we explore the rest of our solar system, our galaxy also, this remains the place where humans are able to breath the air, and feel at home. So we have to look after our Earth. And as we explore, keep that as a priority, to look after Earth and protect it from disasters self induced or things like asteroids our beautiful blue planet. Then we will have a stable basis and confidence, and no need to be rushed; we can then afford to make sensible decisions as we explore the galaxy.
See also: Robert Walker's answer to Are we technologically close to a feasible "von Neumann probe" for exploration?
There are many warnings about the dangers of von Neumann probes. I think it can be done safely. But with great care.
Instead of a "general purpose" machine of science fiction able to make almost anything, the safest thing is to, e.g., design it so it is a reasonably simple machine, and just makes exact copies of itself, no evolution, and with reasonably tightly conditioned responses to situations - with fair amount of autonomy but also reasonably predictable.
After experience with those you might be able to tackle the much more difficult problem of a self replicator able to behave differently in different situations in a more fluid way. And as for evolving self replicators - I think that would be a total No No unless you really had a very clear idea of what you are doing, some advanced understanding we don't have yet.
But - self replicating human explorers of the galaxy are equally scary I think :). Not often said. But by the time they are a thousand light years away - we have no idea what they are doing - could be making von Neumann machines, cyborgs, could be creating new species, could be doing things that are unbelievably stupid according to us but that make sense to them, could be that they are "de-evolving" to creatures with intelligence of a child but vast powers.
We wouldn't know until a thousand years later - by which time there could be almost anything headed our way from the colony. Say, a cloud of von neumann machines designed to turn all star systems into dyson spheres demolishing any planets in the process - someone thought that was a cool idea or it arose out of a von Neumann machine programmed to evolve and solve a problem and that was its solution.
Could be nanobe sized machines, trillions of them, traveling at close to the speed of light, so gets to us before we even know about them, dig into the Oort cloud and make copies of themselves ready for the next step whatever it is, cryptic with technology way advanced ahead of us by many centuries, designed to hide and destroy themselves imperceptibly if discovered so that even when you examine the comets they have burrowed into they just seem like meteoritic dust (say), until suddenly when there are enough of them, they all come to life and do whatever they do next.
Just an example.
Or could be an army of cyborgs, or could be any of the "Alien monsters" of science fiction - only slightly evolved beyond us.
That's my preferred explanation of the Fermi paradox - that sensible ETIs are just as careful about self replicating copies of themselves as they are about Von Neumann machines. And that we will be too when the time comes.
So then - maybe eventually they do colonize the galaxy but if so in subtle careful ways to avoid these problems so probably also with low populations over the entire galaxy.
Or whatever their solution is, if they did it, it clearly is an approach that leads to minimal modification of the galaxy and a hard to detect presence because when we look at the galaxy in our telescopes - as far as we can see it seems totally unmodified and in its natural state. And we may make the same decision also when the time comes.
Where it is no problem to explore the galaxy if you don't colonize. If there were a few million ETI individuals or families or small settlements that tour the galaxy - even if, say, they have immensely long lives of millions of years and touring the galaxy is something every ETI does as a youngster of one or two million years - and there are millions of these ETIs exploring the galaxy right now - so long as they don't colonize and replicate anywhere but return home when finished - they would leave almost no trace of their presence and the nearest would be likely to be light years away.
Leaving a colony of humans somewhere with interstellar travel and colonization capabilities, without forethought about what the implications would be, might be considered as similar to launching an unregulated von Neumann machine, or setting off a nuclear explosion in a crowded city, something that sensible ETIs just would never do. Unthinkable. Because you can see what the potential consequences would be.
I think in the future that may well become unthinkable to almost any advanced ETI. And those that don't think that way, are so reckless, they destroy themselves long before they can be a nuisance to the galaxy - at least - destroy their space faring capabilities, and keep destroying them every time they try to colonize in space - until they become more forward looking.
Because the first space colonies will be unbelievably delicate and easily destroyed. Because if you have space colonies, you have the technology to propel things at tens of kilometers per second. Even an accident at that velocity would totally destroy most ideas for space colonies with a direct hit right away. And deliberate warfare would end up with everyone dead.
So - we need to move forward in some way to a future where we don't do things like that. Otherwise we will never explore the galaxy. And if we are as far seeing as that - then I think we will also choose to explore the galaxy robotically - or if we send humans at all - as explorers that wouldn't think of setting up new colonies until we have thoroughly worked out a way to do that that avoids these issues of unrestricted replication of humans and whatever entities they might create.
We haven't encountered these problems in such an extreme way on the Earth because the whole Earth as soon as it got highly technological was already interconnected, to such an extent that there is no chance at all that one of the countries is more than a few years ahead of any of the others. And so far no possibility of creating self replicators. And if some strange philosophy develops, or viewpoint or approach, the whole world learns about it.
But space colonies could easily be thousands of years ahead of each other. And strange ideas - but not only that - even beings that are independently evolved, and machines, and machine / biology hybrids, and all sorts of things could evolve and they could be hazards to ourselves, to each other and to any other extra-terrestrials out there.
Either we are the first ETIs in our galaxy to have the potential to colonize it - if so it is up to us to find out what to do and to set a good example for the future. And that would suggest we take extreme care because we have no-one else to learn to and tell us what the pitfalls are (except possibly in other galaxies).
Or else - there are other ETIs here already, if so it would be an extraordinary coincidence if they evolved the same time as us, so they would be likely to be a millions, or more likely billions of years old civilization. If so hopefully we detect them eventually and learn from them what to do and what works and what doesn't or is dangerous to do.
If unsure, robots are safest, I mean simple ones, not able to evolve especially, and with limited autonomy. They can be programmed to self destruct. They can go into dormancy for millions of years - if they find an uninteresting solar system say, just leave a few sentinels and go to sleep. They can be programmed safely to visit every star in the galaxy. They can be sterilized so that they don't bring Earth microbes to ET planets.
Safest way to make them would be - non evolving, not "all purpose" machines but perhaps e.g. only designed to be able to reproduce using nickel iron meteorites + silicon, water - some simple machines that let them take the ingredients from a few meteorites to build copies. Only want one or two per solar system. And - each one can create, say, ten copies, but there is a maximum number of generations, say ten. So no chance that through flawed copying they "evolve" anyway. If the copy is not perfect, it destroys itself.
Then - also make them depend on an external signal, something they can't create themselves, and that any ETI can't either, if you can. If they don't get this signal (perhaps based on trapdoor prime ciphers??) say every century or whatever, for an interstellar spaceship (or every year for machines within a system) then they go to sleep or destroy themselves.
If ETIs try to reprogram them, they self destruct. So no other creatures can take them over and make them into unrestricted evolving self replicators.
Something like that. Details to be worked out. But if completely safe, then you could just send out one of these probes into our asteroid belt. It makes ten copies that it sends to the ten nearest stars. Those on arrival make ten more (and start broadcasting findings back to Earth). Those make ten more again and so on. Before long all the nearest stars have them and eventually entire galaxy does. But this process of replication comes to a complete halt after ten generations by which time every star in the galaxy has one of those machines in its system.
Then when they encounter an interesting system, say one with habitable planets, they make more spaceships to explore those systems and tell us what is there.
I'd see that as a possible first phase, done with great care and forethought about possible consequences, so this is just a very preliminary draft idea.
Whether humans colonize or settle or explore - that's a decision for much later once we have a much better understanding of our galaxy and also, hopefully, have managed to develop a little beyond those potentially self destructive approaches to exploration of the galaxy. How exactly that happens remains to be discovered.
And in our solar system - if the first space colonies are based around settlement and exploration - like the ones in Antarctica - I think that is the way ahead. Not push for colonization no matter what. But let it happen naturally where colonies are needed for some purpose. Because we don't need to do a backup of the Earth - that's in some of my other answers here, there are no dangers that would not be better solved by having your backups on Earth not for the next few tens or probably hundreds of million years anyway.
So there is no great rush. Our Earth, no matter what happens in the next few million years (timescale over which new mammal species evolve - so that is a huge future timescale), surely will remain the most habitable place in the solar system for humans.
As we explore the rest of our solar system, our galaxy also, this remains the place where humans are able to breath the air, and feel at home. So we have to look after our Earth. And as we explore, keep that as a priority, to look after Earth and protect it from disasters self induced or things like asteroids our beautiful blue planet. Then we will have a stable basis and confidence, and no need to be rushed; we can then afford to make sensible decisions as we explore the galaxy.
See also: Robert Walker's answer to Are we technologically close to a feasible "von Neumann probe" for exploration?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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