Okay - I think - need to make a distinction between a settlement - which could be temporary - like a science research station, a hotel, retirement home etc - and a colony.
For a settlement - then the Moon - or orbiting Earth. And before long - as in a few decades - I think will have settlements orbiting Mars also - if we can crack the issues of zero gravity (probably with artificial gravity) and cosmic radiation.
But they will be expensive places to build and maintain, like research stations in Antarctica and more so.
Research stations like this one in Antarctica
- but anywhere in space is a far more hostile place to build than Antarctica.
They won't be places that anyone goes to live permanently as a home unless they are multi-billionaires.
I think many Americans at least have idea of space settlement as rather more like this
But - it just can't work like that.
That's just because of physics - they have to be designed to withstand ten tons per square meter outwards pressure and to withstand day night cycles of heat - will have few or no windows - and need to be covered by 4.5 tons per square meter of cosmic radiation shielding. And surrounded by vacuum and need to use complex machinery to create oxygen and to regulate the atmosphere and make sure poisonous gases do not build up. And extract water from ice.
That can't help but be hugely more expensive than your average home on Earth - and require far more on going maintenance. And probably the whole thing has to be replaced every few decades as it's not easy to do more than minor repairs for something like that in the harsh conditions of space.
The first space settlements are bound to be complex heavy things like this
(unity module for the ISS photographed by space shuttle)
Greenhouses if build have to be spherical or hemispherical and made of very strong material able to withstand at least some tons per square meter of outwards pressure.
So - you aren't going to be building homes in these places with bricks and mortar, or log cabins, or such like. Inside of any shelter you create - you need to have complex high tech stuff like this going on to keep the humans alive,
For these types of habitat, then the best place for first settlements is close to Earth because there is so much to go wrong. The ISS only gave limited experience - has no artificial gravity or cosmic radiation shielding and relies on supplies from Earth every few months.
I think we should not send anyone as far as Mars orbit until we have had experience of living at least as long in space, without supply from Earth, closer to Earth first. And - I think for first long term stays in space - should be no further away than the Moon - at furthest - perhaps the L2 position on far side of the Moon (which has been suggested several times as a good place to conduct a telerobitic mission to the Moon - and I think myself is an excellent precursor for an interplantary telerobotic mission e.g. to Mars).
Otherwise I think the chance of an Apollo 13 type disaster, at distance of, say, Mars or Venus - is just too high to contemplate.
As for colonies though - people living permanently in space - that depends on making it far easier to make homes in space.
Only way I can see that happening is to have big habitats - if they can be made low maintenance - large enough to contain thousands of settlers who can then build homes inside them.
So - if on the Moon or planets - big domed cities.
Those could work - but only if we can live long term in low gravity and stay health - which nobody knows. If they have to spin for artificial gravity - then it's probably easier to build them in free space.
Also - there's a major issue on the Moon of constant micro-meteorites hitting the dome - so would need to have repair -and able to deal with larger impacts - and remember that every time it is penetrated - you have up to ten tons per square meter outwards pressure. And still have to shield the settlements within the dome.
And covering an entire domed city on the Moon with cosmic radation shielding would be an engineering challenge - and also mean you have to use mirrors to divert sunlight inside of the dome - it then becomes much like a space colony.
In case of Venus - then can have tensegrity spheres floating in the upper atmosphere.
I think in many ways this is the easiest from an engineering point of view, with same pressure inside and out, and natural cosmic radiation shielding, and far less mass needed per colonist - which in early stages could be shipped from Earth.
And can get much of the material from the atmosphere itself - 90% of a tree is derived from water and CO2 - so you could get much of the construction material for new habitats just by growing trees using the CO2, nitrogen and water from the Venus atmosphere.
Why are we thinking about a Mars colony when a Venus colony would be more technically feasible? It seems that radiation shielded floating colonies could be assembled on Venus, with plastic film and aluminum wire bags, filled with breathable air.
And other possibility - Stanford Torus or O'Neil cylinders.
But is hard to see any of those being built unless there is benefit to Earth immediately to offset the huge costs, which would be into the hundreds of billions or trillions of dollars..
Original idea for Stanford Torus was to build solar satellites, needing ten thousand people in space to do it. But - not sure we need that any more. Might be as easy to build them using mainly telerobots - and automated mining equipment - with just a few people in space to supervise them - especially if we can use extensive use of 3D printers - and maybe send up electronics from Earth.
Anyway - you need some such motivation as that for the colony to offset the costs of building it - even wealthy billionaires couldn't build a Stanford Torus or a domed city or a floating Venus "Cloud nine" with their own money.
Mars surface I see as not a good place to go at all at present. Because humans on the surface would contaminate the planet with Earth microbes - and so destroy or confuse the very thing we are interested to find there - life that evolved independently from Earth - especially with the recent discoveries of possible habitats for present day life on Mars (not yet confirmed but most think it likely that we will confirm them in near future - espepcially the warm seasonal flows which have no other explanation to date other than some form of seasonal liquid, probably salty - seeps of water).
As for terraforming Mars - that is a multi-millennium long project - and not at all sure to succeed - so should be no hurry to start on it - who knows what will be the wishes of our descendants several hundred generations into the future - and on Earth it took millions of years. At any rate no benefit to us just now.
But telerobotic exploration of Mars from orbit - that we could do - as a settlement.
Mars orbit could also be a good place to start a Stanford Torus type colony. The motivation there might be mining Deimos for water some of which could be exported to LEO to offset costs of the colony.
There is the whole question of whether we need to colonize space at all. I don't think we do as you can tell from my other answers here
I think if done without forethought, regulation and care there are many things that could go wrong that would harm both Earth and the future colonists (if any)
Some places in the solar system are extremely sensitive - especially places where life could survive and reproduce - that includes Mars. We can't just let humans colonize those places just as they wish - that would have harmful repercussions on all the other people on Earth who want to study those places in their pristine state. Just as we have quarantine regulations and other rules on the Earth - we need those in space also..
Ownership claims in space could lead to warfare between colonies or between them and Earth - this is addressed to some extent by the Outer Space Treaty not permitting ownership of solar system.
But it's still a major issue - because space colonies are so fragile that just throwing rocks at each other at spacecraft velocities would kill everyone.
Then economically - there are such huge profits to be made in space potentially - that you could end up with individuals or companies in space that earn more per year than even the richest nations on the Earth.
The 2030 "Bill Gates" might have wealth in the trillions - and depending on who he is and what business practices he engages in - could topple governments and change the entire world to his wishes.
The resulting economic imbalances and dependencies which could be just as bad (like the 1973 oil crisis leading to long term debts and poverty for entire countries).
So - some sort of benefit sharing needs to be built in to make sure that the Earth remains safe in the future - beyond the initial stages when indeed space miners may need all the help they can get - to further in the future when they could be too economically powerful for anyone's good.
So - I think that right now we should focus on finding out about the solar system and exploration - and doing things in space that benefit the Earth.
And should keep firmly to the principles of peaceful co-operative exploration of space for benefit of all of humanity - as outlined in the Outer Space Treaty.
Settlements can then arise naturally out of that. And as for long term colonies, people having babies in space and raising families there etc - I think we don't need to hurry that along. Because there are many issues to be addressed and thought through before that is a sensible and safe thing to do, and we can work those out in the course of exploration and settlement.
But - I think good to work on closed system habitats and artificial gravity - and the exploration and settlement would help with colonization if we ever decide we want to do it. But right now - nowhere in space is anywhere as hospitable as deserts on Earth - so - not a good place to colonize .
Right now anywhere in space is very expensive and only suitable for multi-billionaires able to spend billions of dollars a year to maintain their expensive lifestyle in space. And for that matter, at current state of technology - need to be extreme sport enthusiasts who don't mind risking their life, similar to base jumpers. Elon Musk fits the profile perfectly, but I don't think many others do - and - I think myself he would not be permitted to set up a colony on Mars when they start to work through the details of planetary protection issues.
Settlement though - well humans will help greatly with telepresence. Even at distance of the Moon - for a large complex task it could be an overall cost saving to have humans on the spot on the ground or in L2 to control the equipment - at least at present levels of technology.
It's a huge benefit in Mars or Venus orbit once that becomes practical - entire Curiosity mission probably done in a day from Mars orbit - though autonomous robotics is also improving rapidly - so probably would need to re-evaluate it all a couple of decades from now.
But at present anyway - for science value - then humans on the ground on Mars could be a major nuisance not a help - if it turns out that they would introduce Earth life to Mars as seems reasonably likely from the most recent research in the last few years about Mars and extremophiles.
As for O'Neil cylinders - the problem with those is that they need so much atmosphere as you have to fill much of the interior of the cylinder - and if it is as thick as an Earth atmosphere - that's an extra ten tons per square meter and those tons including hard to source materials such as nitrogen.
The Stanford Toruses require much less atmosphere so easier to build and use less resources.
Venus floating cloud colonies far easier to build than either of those - the easiest to bulid of all the ideas for large colonies in space. But of course not nearly as easy to build as a colony on the Earth in a desert here.
You could build a huge domed city in a desert on the Earth - and it would cost far less, and be far easier to maintain - than any colony you could build anywhere in space - because Earth is so close to optimal habitable conditions for humans already even in a desert. And dome doesn't even need to withstand tons per square meter outwards pressure. A geodesic dome, lightweight construction - would work just fine and be very strong, withstand any storms and natural disasters - and easier to maintain than anything you can build in space - for instance - you can work on it without using spacesuits or telerobots, just breathing the air as you work.
Like this proposal to build a dome over Vermont in 1979 Could Encasing Cities in Giant Domes Be an Energy Solution for Our Future?
Or again, you could build a "Cloud nine" tensegrity sphere floating in the Earth's atmosphere just by the lifting power from the heat inside. It's far easier to build a conventional city than one of those - but the idea is practical (stronger than you would think because of the tensegrity construction) and easier to build than a Stanford Torus or the equivalent "Cloud Nine" on Venus.
Similarly also - a city floating on the sea.
All of those are far far easier to build than any space colony - I would imagine at least an order of magnitude easier to build for the same number of colonists - but harder to build than a more conventional Earth colony. And plenty of space to build them here also - in the deserts or floating on the sea.
So bearing that in mind, clearly you need some other reason for building a colony in space, not just as a place to live.
And is no credible disaster on the Earth in less than a few hundred million years that would be worth going into space to avoid, those also are easier avoided by evacuating the impact zone (in case of asteroid impact), and in very wort, most improbable case - building underground or under sea shelters where people can shelter during the moment of impact itself. But - chances we need to do that are tiny - we will probably have evolved to another species before hit by something as big as that.
When enthusiasts talk about going into space to avoid asteroid impacts - I think perhaps they forget about the Spaceguard survey.
By 2020 NASA has been tasked with completing a spaceguard survey of 90% of potential impactors of 140 meters or more - so chance that a 10 km asteroid is lurking undetected by then will be tiny.
And surely eventually will have even more refined surveys. Long before there's a reasonable chance of getting hit by a giant asteroid (most likely to happen some hundreds of thousands of generations into the future) - if we continue as a technological civilization - we will probably have thousands of years of warning to prepare or to deflect it.
If we continue as a technological space faring species for a few more centuries, I think it will no longer be a problem for us, we'll be able to deflect it or do something or other about it with the technology we have available then.
I can see larger scale settlement, verging on colonies, happening naturally though - for - e.g. making solar panels - or mining Deimos - as natural outgrowth of space mining and technology focused on benefiting the Earth.
Robert Walker's answer to Are the moons of Mars, Phobos and Deimos, also suitable for off-world colonization?
Probably a few thousand people rather than millions or billions.- if there are things that are worth doing that do need thousands of people living in space.
For millions or billions of people to live in space - you would need some major game changing technology - such as nanoscale 3D printers and self replicating machines perhaps.
And - I'm not myself entirely sure that's a future to look forward to - as so many people in space - each with immense power - with self replicating machines even enough power for an individual to start off an individual project to change the structure of all the solar systems in the entire galaxy - doesn't seem a very safe future to me.
I think that will need a lot of care or regulation, or a change in the way humans behave before it is safe for us or the galaxy. Without that then would probably just destroy itself - at least all the space colonies - hopefully before anyone sets off a premature self replicating "change the galaxy" project.
See also Robert Walker's answer to If we actually find a habitable planet with liquid water, how long will it be until people start living there?
Robert Walker's answer to If we knew that Earth would be destroyed in 50 years, could humanity work together to build enough space planes and space stations to save the entire human race?
Robert Walker's answer to Is it really likely future space colonies would try to gain "independence?"
For a settlement - then the Moon - or orbiting Earth. And before long - as in a few decades - I think will have settlements orbiting Mars also - if we can crack the issues of zero gravity (probably with artificial gravity) and cosmic radiation.
But they will be expensive places to build and maintain, like research stations in Antarctica and more so.
Research stations like this one in Antarctica
They won't be places that anyone goes to live permanently as a home unless they are multi-billionaires.
I think many Americans at least have idea of space settlement as rather more like this
But - it just can't work like that.
That's just because of physics - they have to be designed to withstand ten tons per square meter outwards pressure and to withstand day night cycles of heat - will have few or no windows - and need to be covered by 4.5 tons per square meter of cosmic radiation shielding. And surrounded by vacuum and need to use complex machinery to create oxygen and to regulate the atmosphere and make sure poisonous gases do not build up. And extract water from ice.
That can't help but be hugely more expensive than your average home on Earth - and require far more on going maintenance. And probably the whole thing has to be replaced every few decades as it's not easy to do more than minor repairs for something like that in the harsh conditions of space.
The first space settlements are bound to be complex heavy things like this
Greenhouses if build have to be spherical or hemispherical and made of very strong material able to withstand at least some tons per square meter of outwards pressure.
So - you aren't going to be building homes in these places with bricks and mortar, or log cabins, or such like. Inside of any shelter you create - you need to have complex high tech stuff like this going on to keep the humans alive,
NEED TO BUILD CLOSE TO HOME TO START WITH
For these types of habitat, then the best place for first settlements is close to Earth because there is so much to go wrong. The ISS only gave limited experience - has no artificial gravity or cosmic radiation shielding and relies on supplies from Earth every few months.
I think we should not send anyone as far as Mars orbit until we have had experience of living at least as long in space, without supply from Earth, closer to Earth first. And - I think for first long term stays in space - should be no further away than the Moon - at furthest - perhaps the L2 position on far side of the Moon (which has been suggested several times as a good place to conduct a telerobitic mission to the Moon - and I think myself is an excellent precursor for an interplantary telerobotic mission e.g. to Mars).
Otherwise I think the chance of an Apollo 13 type disaster, at distance of, say, Mars or Venus - is just too high to contemplate.
COLONIES NEED EASY PLACES TO BUILD HOUSES - INSIDE HUGE HABITATS MOST LIKELY
As for colonies though - people living permanently in space - that depends on making it far easier to make homes in space.
Only way I can see that happening is to have big habitats - if they can be made low maintenance - large enough to contain thousands of settlers who can then build homes inside them.
So - if on the Moon or planets - big domed cities.
Those could work - but only if we can live long term in low gravity and stay health - which nobody knows. If they have to spin for artificial gravity - then it's probably easier to build them in free space.
Also - there's a major issue on the Moon of constant micro-meteorites hitting the dome - so would need to have repair -and able to deal with larger impacts - and remember that every time it is penetrated - you have up to ten tons per square meter outwards pressure. And still have to shield the settlements within the dome.
And covering an entire domed city on the Moon with cosmic radation shielding would be an engineering challenge - and also mean you have to use mirrors to divert sunlight inside of the dome - it then becomes much like a space colony.
In case of Venus - then can have tensegrity spheres floating in the upper atmosphere.
I think in many ways this is the easiest from an engineering point of view, with same pressure inside and out, and natural cosmic radiation shielding, and far less mass needed per colonist - which in early stages could be shipped from Earth.
And can get much of the material from the atmosphere itself - 90% of a tree is derived from water and CO2 - so you could get much of the construction material for new habitats just by growing trees using the CO2, nitrogen and water from the Venus atmosphere.
And other possibility - Stanford Torus or O'Neil cylinders.
But is hard to see any of those being built unless there is benefit to Earth immediately to offset the huge costs, which would be into the hundreds of billions or trillions of dollars..
Original idea for Stanford Torus was to build solar satellites, needing ten thousand people in space to do it. But - not sure we need that any more. Might be as easy to build them using mainly telerobots - and automated mining equipment - with just a few people in space to supervise them - especially if we can use extensive use of 3D printers - and maybe send up electronics from Earth.
Anyway - you need some such motivation as that for the colony to offset the costs of building it - even wealthy billionaires couldn't build a Stanford Torus or a domed city or a floating Venus "Cloud nine" with their own money.
NOT MARS SURFACE - THOUGH MARS ORBIT OKAY
Mars surface I see as not a good place to go at all at present. Because humans on the surface would contaminate the planet with Earth microbes - and so destroy or confuse the very thing we are interested to find there - life that evolved independently from Earth - especially with the recent discoveries of possible habitats for present day life on Mars (not yet confirmed but most think it likely that we will confirm them in near future - espepcially the warm seasonal flows which have no other explanation to date other than some form of seasonal liquid, probably salty - seeps of water).
As for terraforming Mars - that is a multi-millennium long project - and not at all sure to succeed - so should be no hurry to start on it - who knows what will be the wishes of our descendants several hundred generations into the future - and on Earth it took millions of years. At any rate no benefit to us just now.
But telerobotic exploration of Mars from orbit - that we could do - as a settlement.
Mars orbit could also be a good place to start a Stanford Torus type colony. The motivation there might be mining Deimos for water some of which could be exported to LEO to offset costs of the colony.
There is the whole question of whether we need to colonize space at all. I don't think we do as you can tell from my other answers here
WHY SPACE COLONIZATION MUST BE REGULATED
I think if done without forethought, regulation and care there are many things that could go wrong that would harm both Earth and the future colonists (if any)
SCIENCE ISSUES AND CONTAMINATION
Some places in the solar system are extremely sensitive - especially places where life could survive and reproduce - that includes Mars. We can't just let humans colonize those places just as they wish - that would have harmful repercussions on all the other people on Earth who want to study those places in their pristine state. Just as we have quarantine regulations and other rules on the Earth - we need those in space also..
ECONOMIC AND POLITICAL ISSUES
Ownership claims in space could lead to warfare between colonies or between them and Earth - this is addressed to some extent by the Outer Space Treaty not permitting ownership of solar system.
But it's still a major issue - because space colonies are so fragile that just throwing rocks at each other at spacecraft velocities would kill everyone.
Then economically - there are such huge profits to be made in space potentially - that you could end up with individuals or companies in space that earn more per year than even the richest nations on the Earth.
The 2030 "Bill Gates" might have wealth in the trillions - and depending on who he is and what business practices he engages in - could topple governments and change the entire world to his wishes.
The resulting economic imbalances and dependencies which could be just as bad (like the 1973 oil crisis leading to long term debts and poverty for entire countries).
So - some sort of benefit sharing needs to be built in to make sure that the Earth remains safe in the future - beyond the initial stages when indeed space miners may need all the help they can get - to further in the future when they could be too economically powerful for anyone's good.
FOCUS ON EXPLORATION
So - I think that right now we should focus on finding out about the solar system and exploration - and doing things in space that benefit the Earth.
And should keep firmly to the principles of peaceful co-operative exploration of space for benefit of all of humanity - as outlined in the Outer Space Treaty.
Settlements can then arise naturally out of that. And as for long term colonies, people having babies in space and raising families there etc - I think we don't need to hurry that along. Because there are many issues to be addressed and thought through before that is a sensible and safe thing to do, and we can work those out in the course of exploration and settlement.
But - I think good to work on closed system habitats and artificial gravity - and the exploration and settlement would help with colonization if we ever decide we want to do it. But right now - nowhere in space is anywhere as hospitable as deserts on Earth - so - not a good place to colonize .
LIVING PERMANENTLY IN SPACE - FOR EXTREME SPORTS LOVING BILLIONAIRES ONLY RIGHT NOW
Right now anywhere in space is very expensive and only suitable for multi-billionaires able to spend billions of dollars a year to maintain their expensive lifestyle in space. And for that matter, at current state of technology - need to be extreme sport enthusiasts who don't mind risking their life, similar to base jumpers. Elon Musk fits the profile perfectly, but I don't think many others do - and - I think myself he would not be permitted to set up a colony on Mars when they start to work through the details of planetary protection issues.
SETTLEMENT - IN PLACES WHERE HUMANS "ON THE SPOT" ARE OF VALUE
Settlement though - well humans will help greatly with telepresence. Even at distance of the Moon - for a large complex task it could be an overall cost saving to have humans on the spot on the ground or in L2 to control the equipment - at least at present levels of technology.
It's a huge benefit in Mars or Venus orbit once that becomes practical - entire Curiosity mission probably done in a day from Mars orbit - though autonomous robotics is also improving rapidly - so probably would need to re-evaluate it all a couple of decades from now.
But at present anyway - for science value - then humans on the ground on Mars could be a major nuisance not a help - if it turns out that they would introduce Earth life to Mars as seems reasonably likely from the most recent research in the last few years about Mars and extremophiles.
WHY STANFORD TORUSES ARE BETTER THAN O'NEIL CYLINDERS IN EARLY STAGES
As for O'Neil cylinders - the problem with those is that they need so much atmosphere as you have to fill much of the interior of the cylinder - and if it is as thick as an Earth atmosphere - that's an extra ten tons per square meter and those tons including hard to source materials such as nitrogen.
The Stanford Toruses require much less atmosphere so easier to build and use less resources.
Venus floating cloud colonies far easier to build than either of those - the easiest to bulid of all the ideas for large colonies in space. But of course not nearly as easy to build as a colony on the Earth in a desert here.
HUGE DOMED CITY IN AN EARTH DESERT - OR "CLOUD NINE" TYPE FLOATING TENSEGRITY SPHERE - FAR EASIER TO BUILD AND MAINTAIN
You could build a huge domed city in a desert on the Earth - and it would cost far less, and be far easier to maintain - than any colony you could build anywhere in space - because Earth is so close to optimal habitable conditions for humans already even in a desert. And dome doesn't even need to withstand tons per square meter outwards pressure. A geodesic dome, lightweight construction - would work just fine and be very strong, withstand any storms and natural disasters - and easier to maintain than anything you can build in space - for instance - you can work on it without using spacesuits or telerobots, just breathing the air as you work.
Like this proposal to build a dome over Vermont in 1979 Could Encasing Cities in Giant Domes Be an Energy Solution for Our Future?
Or again, you could build a "Cloud nine" tensegrity sphere floating in the Earth's atmosphere just by the lifting power from the heat inside. It's far easier to build a conventional city than one of those - but the idea is practical (stronger than you would think because of the tensegrity construction) and easier to build than a Stanford Torus or the equivalent "Cloud Nine" on Venus.
All of those are far far easier to build than any space colony - I would imagine at least an order of magnitude easier to build for the same number of colonists - but harder to build than a more conventional Earth colony. And plenty of space to build them here also - in the deserts or floating on the sea.
So bearing that in mind, clearly you need some other reason for building a colony in space, not just as a place to live.
And is no credible disaster on the Earth in less than a few hundred million years that would be worth going into space to avoid, those also are easier avoided by evacuating the impact zone (in case of asteroid impact), and in very wort, most improbable case - building underground or under sea shelters where people can shelter during the moment of impact itself. But - chances we need to do that are tiny - we will probably have evolved to another species before hit by something as big as that.
SPACEGUARD SURVEY OF POTENTIAL IMPACTORS
When enthusiasts talk about going into space to avoid asteroid impacts - I think perhaps they forget about the Spaceguard survey.
By 2020 NASA has been tasked with completing a spaceguard survey of 90% of potential impactors of 140 meters or more - so chance that a 10 km asteroid is lurking undetected by then will be tiny.
And surely eventually will have even more refined surveys. Long before there's a reasonable chance of getting hit by a giant asteroid (most likely to happen some hundreds of thousands of generations into the future) - if we continue as a technological civilization - we will probably have thousands of years of warning to prepare or to deflect it.
If we continue as a technological space faring species for a few more centuries, I think it will no longer be a problem for us, we'll be able to deflect it or do something or other about it with the technology we have available then.
LARGE SCALE SETTLEMENT
I can see larger scale settlement, verging on colonies, happening naturally though - for - e.g. making solar panels - or mining Deimos - as natural outgrowth of space mining and technology focused on benefiting the Earth.
Robert Walker's answer to Are the moons of Mars, Phobos and Deimos, also suitable for off-world colonization?
Probably a few thousand people rather than millions or billions.- if there are things that are worth doing that do need thousands of people living in space.
FOR BILLIONS OF PEOPLE TO LIVE IN SPACE
For millions or billions of people to live in space - you would need some major game changing technology - such as nanoscale 3D printers and self replicating machines perhaps.
And - I'm not myself entirely sure that's a future to look forward to - as so many people in space - each with immense power - with self replicating machines even enough power for an individual to start off an individual project to change the structure of all the solar systems in the entire galaxy - doesn't seem a very safe future to me.
I think that will need a lot of care or regulation, or a change in the way humans behave before it is safe for us or the galaxy. Without that then would probably just destroy itself - at least all the space colonies - hopefully before anyone sets off a premature self replicating "change the galaxy" project.
See also Robert Walker's answer to If we actually find a habitable planet with liquid water, how long will it be until people start living there?
Robert Walker's answer to If we knew that Earth would be destroyed in 50 years, could humanity work together to build enough space planes and space stations to save the entire human race?
Robert Walker's answer to Is it really likely future space colonies would try to gain "independence?"
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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