# Destiny of humanity and complex life on the Earth

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My premise is this, there are basically three ultimate destinies for humanity and complex life on the Earth.

1. We stay here and ride out the Earth and become extinct along with everything else when a natural disaster of some sort wipes out life on the Earth.

2. Humans colonize the solar system by Terra forming other planets and eventually go to the stars and do the same thing there. We would travel via very fast (near C)space craft to other stars with suitable planets, we might take some complex life with us.

3. We colonize the solar system through orbiting colonies and bypass planets altogether. Using these huge colony ships similar to O'Neil cylinders we can spread out slowly and occupy the Galaxy in a few hundred thousands years. again we would take much of Earth's complex life with us. Stars with large populations of asteroid like bodies would be preferred. Tau Ceti is an example of this type of star.

If complex life is as rare as some think then we could be thought of as spreading complex life around the galaxy.

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My premise is this, there are basically three ultimate destinies for humanity and complex life on the Earth.

Only three??? I'm pretty certain that there are more options.

1. We stay here and ride out the Earth and become extinct along with everything else when a natural disaster of some sort wipes out life on the Earth.

I don't like the look of this option I hope I'm not alive if humanity ultimately chooses this path.

2. Humans colonize the solar system by Terra forming other planets and eventually go to the stars and do the same thing there. We would travel via very fast (near C)space craft to other stars with suitable planets, we might take some complex life with us.

Terraforming planets in our solar system would be easy enough, but I'm not sure how feasible it would be on another star system, especially since the colonists won't be able to take a lot of things with them. The third option though:

3. We colonize the solar system through orbiting colonies and bypass planets altogether. Using these huge colony ships similar to O'Neil cylinders we can spread out slowly and occupy the Galaxy in a few hundred thousands years. again we would take much of Earth's complex life with us. Stars with large populations of asteroid like bodies would be preferred. Tau Ceti is an example of this type of star.

Seems to be the most plausible of them all, assuming we don't wipe ourselves out first (or revert back to the dark ages). This is certainly doable within the next couple of centuries. Although, I will dispute your prediction about colonizing the galaxy in a few hundred thousand years, I would place it at a few million years.

If complex life is as rare as some think then we could be thought of as spreading complex life around the galaxy.

I don't think complex life is rare. And all of the proponents of this idea (e.g. the Rare Earth Hypothesis) seem to be employing the infamous argumentum ad ignorantiam. Of course, if you mean a technological species, then that might be much more rare (or very rare that we would find such a species that is as far down the road as we are).

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Only three??? I'm pretty certain that there are more options.

I'd like to entertain more if you can think of them.

I don't like the look of this option I hope I'm not alive if humanity ultimately chooses this path.

Life on the Earth will indeed eventually become extinct no matter what we do. If nothing else the sun will brighten to the point that complex life will become impossible. this will probably happen in a couple hundred million years for sure, some say much sooner.

Terraforming planets in our solar system would be easy enough, but I'm not sure how feasible it would be on another star system, especially since the colonists won't be able to take a lot of things with them. The third option though:

Actually Terra forming even Mars will take as much time as colonizing the galaxy, a couple hundred thousand years anyway.

Seems to be the most plausible of them all, assuming we don't wipe ourselves out first (or revert back to the dark ages). This is certainly doable within the next couple of centuries. Although, I will dispute your prediction about colonizing the galaxy in a few hundred thousand years, I would place it at a few million years.

Some studies have been done that show if you could send out a colony ship every few hundred years as you go to each star. Say two ships from the Earth to two near by stars then 500 years later two ships from each of these stars and so on it wouldn't be but a few hundred thousand years before we could be around every suitable star in the galaxy.

I don't think complex life is rare. And all of the proponents of this idea (e.g. the Rare Earth Hypothesis) seem to be employing the infamous argumentum ad ignorantiam. Of course, if you mean a technological species, then that might be much more rare (or very rare that we would find such a species that is as far down the road as we are).

I waver back and forth on this issue, some of the arguments for rare complex life are quite compelling but it assumes that complex life every where has to have the same conditions we do and you cannot draw a curve from one data point. We don't even know if what we think of as life is even the most common life in the universe, we might be a rare fluke and silicon life is everywhere else.

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Life on the Earth will indeed eventually become extinct no matter what we do. If nothing else the sun will brighten to the point that complex life will become impossible. this will probably happen in a couple hundred million years for sure, some say much sooner.

Well, yeah, I knew that! Although, most estimates give around a billion years or so: http://www.newscientist.com/article/mg14219191.900.html

Actually Terra forming even Mars will take as much time as colonizing the galaxy, a couple hundred thousand years anyway.

Estimates vary, ranging from a few decades to hundreds of thousands of years. I'm not sure which of them to believe, but I'm pretty certain (my opinion only) that we could do it in less than a 1000. After all, we've managed to change the face of our own planet in less than a century, and we have the potential to do a lot more to it in a very short amount of time. Whether this is a good thing or a bad thing remains to be seen...

Some studies have been done that show if you could send out a colony ship every few hundred years as you go to each star. Say two ships from the Earth to two near by stars then 500 years later two ships from each of these stars and so on it wouldn't be but a few hundred thousand years before we could be around every suitable star in the galaxy.

See, that's the problem. It assumes that every society that leaves Earth will either make it or decide to continue the colonization of the galaxy once they settle down. It is not a good idea to send out only 2 ships anyways because both of them could get destroyed. And if they land on a system that is remarkably resource poor or metal poor then there will not be much in the way of interstellar colonization from that society. And that's not even the tip of the iceberg (e.g. cultural, political, economic, technological etc could come into play).

Just think of what happened to some Polynesian societies; not every one of them (in fact, most of them) decided to embark on a colonization journey once they settled down, and some of them couldn't even if they wanted to because the islands were too resource poor. It took a full 4000 years (even though they could have presumably done it in a couple of centuries given their seafaring skills) to colonize the Pacific. And on top of that, the Pacific Ocean is not quite as big as an entire galaxy (and the engineering challenges, energy and resources necessary to overcome is much greater for colonizing a galaxy than an ocean).

For the Earth in general, we still haven't been able to accomplish the task after 50,000 years, when we left Africa, as Antarctica still remains uninhabited.

I waver back and forth on this issue, some of the arguments for rare complex life are quite compelling but it assumes that complex life every where has to have the same conditions we do and you cannot draw a curve from one data point. We don't even know if what we think of as life is even the most common life in the universe, we might be a rare fluke and silicon life is everywhere else.

That's true. Which is why I'm not a fan of the rare Earth hypothesis at all.

Edited by I_Pwn_Crackpots
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Considering the Milky Way is approximately 100,000 light years in diameter, we'd need near lightspeed or faster-than-light travel to colonize the entire galaxy in 120,000 years.

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There was an article in Scientific American about 12 years ago by a couple of NASA scientists on travel between stars. There are definite limits to speed. We cannot go faster than light, based on current theory. If we want to travel at a high fraction of light speed, we will fail. We need to carry enough reaction mass to decelerate from our top speed. The NASA guys suggested that, in about 1000 years, we should be able to construct starships able to travel at 0.1 to 0.2c.

Based on this, and a few other numbers, it is possible to calculate how long it will take to colonise the entire galaxy. Population growth, it turns out, is not much of a limit. Humanity can reproduce faster than we can spread. The main limit is speed of starships.

Depending on the assumptions in your calculations, the galaxy can be colonised in a time varying between 500,000 years and 10 million.

For example : If we assume an advanced culture that can carry frozen embryos, which will be thawed and developed by long lived computers/robots, and a speed of 0.2 c, then the first starships can get to the far side of the galaxy in 350,000 years, assuming they can follow a direct route. If the world is dominated by colonisation fanatics sending out vast numbers of ships, and the star born descendents follow this fanaticism, then total colonisation in less than 500,000 years is theoretically possible.

This is, of course, unlikely. The real total colonisation time is likely to be far greater.

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Well, yeah, I knew that! Although, most estimates give around a billion years or so: http://www.newscientist.com/article/mg14219191.900.html

There are more than one school of thought on this, some think the sun will warm up faster than others and I thin the 1 billion mark is for all life, complex life will die out much sooner.

Estimates vary, ranging from a few decades to hundreds of thousands of years. I'm not sure which of them to believe, but I'm pretty certain (my opinion only) that we could do it in less than a 1000. After all, we've managed to change the face of our own planet in less than a century, and we have the potential to do a lot more to it in a very short amount of time. Whether this is a good thing or a bad thing remains to be seen...

Mars may or may not be a harder nut to crack, no way to know anyway you look at it but mars too will become uninhabitable at about the same time the earth does.

See, that's the problem. It assumes that every society that leaves Earth will either make it or decide to continue the colonization of the galaxy once they settle down. It is not a good idea to send out only 2 ships anyways because both of them could get destroyed. And if they land on a system that is remarkably resource poor or metal poor then there will not be much in the way of interstellar colonization from that society. And that's not even the tip of the iceberg (e.g. cultural, political, economic, technological etc could come into play).

I was just using 2 colony ships as an example, The Earth could produce thousands of them as could each colony. Or a colony could fail but i am not talking about colonizing planets, I am talking about orbiting colonies that exist independent of planets, possibly torus shaped rotating to produce artificial gravity with it's own ecosystem inside, miles across.

Just think of what happened to some Polynesian societies; not every one of them (in fact, most of them) decided to embark on a colonization journey once they settled down, and some of them couldn't even if they wanted to because the islands were too resource poor. It took a full 4000 years (even though they could have presumably done it in a couple of centuries given their seafaring skills) to colonize the Pacific. And on top of that, the Pacific Ocean is not quite as big as an entire galaxy (and the engineering challenges, energy and resources necessary to overcome is much greater for colonizing a galaxy than an ocean).

I don't think its a fair comparison, the Polynesians did a very good job with very slow speeds and no way of knowing where they were going or what they would find when they got there. a self contained orbiting colony could traverse the distance between stars slowly in a few hundred years. make copies of it's self from asteroid like material and then go on. Each stop could produce hundreds of colonies, some would leave some would stay awhile. Some stops wouldn't produce anything and the ships would go on.

For the Earth in general, we still haven't been able to accomplish the task after 50,000 years, when we left Africa, as Antarctica still remains uninhabited.

Don't you think that Antarctica has little or no bearing on what we are talking about? Primitives didn't have the technology to survive there and we don't want to live in a place so bare and stark.

That's true. Which is why I'm not a fan of the rare Earth hypothesis at all.

A couple more data points and we'll know.

Considering the Milky Way is approximately 100,000 light years in diameter, we'd need near lightspeed or faster-than-light travel to colonize the entire galaxy in 120,000 years.

I didn't say a 120,000 years I said a few hundred thousand years and if we colonized via artificial colony worlds the number could increase exponentially until the expanding front of human colonization was a wave encompassing hundreds of stars a day. Even if it took a million years it would still be in the blink of an eye geologically speaking. I gave an example of one colony sending out two self contained colonies and then each of those two sending out two to make four, take that out 500 hundred times and see how many colonies you would have. then think of each colony sending out hundreds of other colonies each time as well as each colony moving on after the easily obtained resources of a star system are used up. You get a wave front of colonization that is astounding to say the least. Since no planets are needed even stars with no planets or stars that are unsuitable for planets could be used. If during the travel of a colony they pass a world that is suitable for complex life but has no such life we could leave some there. this of course assumes complex life is rare. If complex life is common then we would probably avoid planetary systems with complex life to avoid competition with any possible intelligent natives.

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There are more than one school of thought on this, some think the sun will warm up faster than others and I thin the 1 billion mark is for all life, complex life will die out much sooner.

Not that much sooner. We have at least half a billion years before we truly have to worry about the Earth becoming too hot for us complex life forms.

Mars may or may not be a harder nut to crack, no way to know anyway you look at it but mars too will become uninhabitable at about the same time the earth does.

Mars is the most Earth-Like planet in the solar system. That's why I don't think it will take that long to terraform. It's the same with Titan. But if you are referring to Venus, that will probably take thousands of years to properly terraform as it has little to no water present. And then, I'm not sure about the challenges of terraforming gas giants, but I'm pretty certain it's near impossible to do that.

I was just using 2 colony ships as an example, The Earth could produce thousands of them as could each colony. Or a colony could fail but i am not talking about colonizing planets, I am talking about orbiting colonies that exist independent of planets, possibly torus shaped rotating to produce artificial gravity with it's own ecosystem inside, miles across.

It doesn't really matter, because they will need to be around star systems to sustain themselves. Whether or not they land on planets is up the colonists. But, a planet does offer important advantages that colony ships can't provide, such as safety from radiation/space objects, gravity, living space, a stable biosphere, etc.

I don't think its a fair comparison, the Polynesians did a very good job with very slow speeds and no way of knowing where they were going or what they would find when they got there. a self contained orbiting colony could traverse the distance between stars slowly in a few hundred years. make copies of it's self from asteroid like material and then go on. Each stop could produce hundreds of colonies, some would leave some would stay awhile. Some stops wouldn't produce anything and the ships would go on.

I do. We may know where the stars are at, but we are pretty much in the same position as the Austronesians were when they left for the Pacific islands. We also don't know where to go, and before we decide on a star system we would have to send probes to gather information. Or just accept the risks and go to that star system anyway. At the very least, this doubles the time necessary to actually go out and make stable colonies on those star systems, even if we launch the probes ahead of time.

And there is only so much we can carry on our ships before it becomes impossible to accelerate and decelerate it at a significant fraction of the speed of light. So, it is not likely that you can create hundreds of colonies from just one ship, unless you reduce the speed that it can travel (in which case it will take much longer to colonize the entire galaxy...). Maybe two or three colonies, but not hundreds, and they all would have to stay in the same star system (unless the next one is very close, say 1-2 light years away).

After decades, or hundreds of years of traveling across space, I'm pretty certain that most societies will settle down for an indefinite period of time before they too decide to embark on a colonization trip (IF their star systems have the proper materials and resources). Or not at all, depending on the society. When they first land, there will be no industry and food and water will be the most important things.

This is just the tip of the iceberg. I compared it to the Polynesian colonization of the Pacific because it will be mostly like that, just a bunch of star hopping, and whether or not our hypothetical colonists will get a quality star system will be left to pure chance. IF they get a good star system then they could continue the colonization process, IF they decide to also invest in the resources necessary. If not, then that's one less colony that will be able to help conquer the galaxy. It was the same for the Polynesians, if the island was large and had lots of useful resources then they could develop relatively advanced societies (and then could afford to build their own canoes to continue the colonization process).

Don't you think that Antarctica has little or no bearing on what we are talking about? Primitives didn't have the technology to survive there and we don't want to live in a place so bare and stark.

You missed the point. My point is that after 50,000 years, we still haven't been able to colonize a significant fraction of the Earth, despite modern technology. Antarctica was just pulled out as an example. Other examples include the Sahara Desert and vast areas of Siberia. In fact, we as a species only occupy less than 20% of the total surface area of our own planet despite having more than 50,000 years to do the job. In some cases, it's easier to get to the moon than it is to reach certain areas of our own planet.

At the same time, there are regions of the galaxy that would be completely unsuitable for human colonization, such as the galactic core or nebulas, or freezing ice worlds like Pluto. So, in that sense, Antarctica is relevant because it shows that we are not able to fully colonize our own planet, let alone the entire galaxy which will have environments far hazardous than that of Antarctica.

If we have great difficulty occupying our own planet completely, what makes any of us think that we could colonize the entire galaxy in a few hundred thousand years?

Given 5 million years, though, then we as a species (or our successors) might occupy a significant fraction of our galaxy. A few hundred thousand years is a bit of a stretch and very, very unlikely.

A couple more data points and we'll know.

I'm patient . I'm pretty certain we will know the answer to that question far, far sooner than we will colonize the galaxy, or reach the next star system on our own.

If complex life is common then we would probably avoid planetary systems with complex life to avoid competition with any possible intelligent natives.

What makes you think we would do that? Unless they possess nuclear weapons or are heavily industrialized, I have an extremely hard time believing that our future colonists would just simply "leave them alone". If anything, if a given planet has a complex biosphere that would make it more likely that we will inhabit it (unless, of course, the planet is completely incompatible with human life, which is very unlikely)

Edited by I_Pwn_Crackpots
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Not that much sooner. We have at least half a billion years before we truly have to worry about the Earth becoming too hot for us complex life forms.

The earth wouldn't have to become very much hotter to significantly curb complex life forms. The upper limit for complex life is somewhere around 50C but that is for some very tough plants, animals need temps lower than that. Most of complex life on earth lives below 40C average.

Mars is the most Earth-Like planet in the solar system. That's why I don't think it will take that long to terraform. It's the same with Titan. But if you are referring to Venus, that will probably take thousands of years to properly terraform as it has little to no water present. And then, I'm not sure about the challenges of terraforming gas giants, but I'm pretty certain it's near impossible to do that.

Terra forming is just a stop gag measure anyway you look at it. Self contained orbiting colony world/ships are the only way to go.

It doesn't really matter, because they will need to be around star systems to sustain themselves. Whether or not they land on planets is up the colonists. But, a planet does offer important advantages that colony ships can't provide, such as safety from radiation/space objects, gravity, living space, a stable biosphere, etc.

No they only need star systems for raw materials, a properly build and maintained colony will provide everything humans need, including an ecology in huge ship spun for artificial gravity. Inside they would be like a valley on the Earth rolled up. They would not be sterile tin cans only to be used to travel in. People would live in them and have no knowledge of or need of planets.

I do. We may know where the stars are at, but we are pretty much in the same position as the Austronesians were when they left for the Pacific islands. We also don't know where to go, and before we decide on a star system we would have to send probes to gather information. Or just accept the risks and go to that star system anyway. At the very least, this doubles the time necessary to actually go out and make stable colonies on those star systems, even if we launch the probes ahead of time.

Star wisp type probes could be sent out ahead of the colony at very near C to report back about what lay ahead. If no suitable material was found in orbit around a star, unlikely that nothing would orbit a star, the colony ship could go one to the next star.

And there is only so much we can carry on our ships before it becomes impossible to accelerate and decelerate it at a significant fraction of the speed of light. So, it is not likely that you can create hundreds of colonies from just one ship, unless you reduce the speed that it can travel (in which case it will take much longer to colonize the entire galaxy...). Maybe two or three colonies, but not hundreds, and they all would have to stay in the same star system (unless the next one is very close, say 1-2 light years away).

Using things like magnetic sails even a large colony/world ship could be sent to another star. using the stellar wind to accelerate and decelerate.

After decades, or hundreds of years of traveling across space, I'm pretty certain that most societies will settle down for an indefinite period of time before they too decide to embark on a colonization trip (IF their star systems have the proper materials and resources). Or not at all, depending on the society. When they first land, there will be no industry and food and water will be the most important things.

They will not land, they will simply go into orbit and start using asteroid/cometary material to build new ships and replace volatiles and other lost compounds. planets are not only not necessary they are not an easy source of materials and be avoided.

You missed the point. My point is that after 50,000 years, we still haven't been able to colonize a significant fraction of the Earth, despite modern technology. Antarctica was just pulled out as an example. Other examples include the Sahara Desert and vast areas of Siberia. In fact, we as a species only occupy less than 20% of the total surface area of our own planet despite having more than 50,000 years to do the job. In some cases, it's easier to get to the moon than it is to reach certain areas of our own planet.

Name a land area that is harder to get to than the moon please. We do not colonize these areas for good solid reasons, we cannot live there, an orbiting colony would be a much better place to live than Antarctica or the Sahara. Most of the Earth surface is not suitable for human needs. Our colony world/ships will be great environments with controlled weather and 100% suitable for humans. since they will be controlled environments no need to worry about finding a place to live among the stars all we need is raw materials.

At the same time, there are regions of the galaxy that would be completely unsuitable for human colonization, such as the galactic core or nebulas, or freezing ice worlds like Pluto. So, in that sense, Antarctica is relevant because it shows that we are not able to fully colonize our own planet, let alone the entire galaxy which will have environments far hazardous than that of Antarctica.

We would avoid areas where our ships couldn't protect us and planets are irrelevant. small ice worlds could be broken up for materials.

If we have great difficulty occupying our own planet completely, what makes any of us think that we could colonize the entire galaxy in a few hundred thousand years?

Because we wouldn't be occupying planets!

Given 5 million years, though, then we as a species (or our successors) might occupy a significant fraction of our galaxy. A few hundred thousand years is a bit of a stretch and very, very unlikely.

Even 10 million years is a eye blink in terms of the galaxy, the only other option is to sit and wait for extinction.

I'm patient . I'm pretty certain we will know the answer to that question far, far sooner than we will colonize the galaxy, or reach the next star system on our own.

we need to get things going by pursuing the exploration and exploitation of our solar system now. a simple natural disaster could keep all of it from ever happening. Once we are in space and colonizing the asteroids it will be much more difficult to kill us all and we will take complex Earth life with us, if nothing else for food.

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A few points.

The polynesians took 12,000 years to colonise the Pacific, with the Maori reaching my country only 800 years ago. The reason they took so long was primitive technology, and tiny destinations separated by vast distances. Star travel will not be the same, since we can see our destination. Interestingly, the polynesians grew sweet potato, which is a South American crop. They lived on Easter Island, much closer to South America than to their origin in Asia. They obviously visited South America also.

The Sahara desert is definitely lived in and fully colonised. It is just that its water supply is low meaning a low carrying capacity - thus low population. The reason we do not live in Antarctica is international treaty. Inuits would have no problem living there. Indeed, neither would westerners, though they would be dependent on exploiting natural resources and trading for food.

I agree with Moontanman in that humans will not need planets. And it is probable that most star systems will not have 'habitable' planets. Instead, we will live in massive space habitats, and harvest cometary debris and the like, for resources. Humanity probably will have practical nuclear fusion energy within 100 years. By the time we leave our own star system in about 1000 years, it will be highly developed. With abundant fusion energy, a space habitat of sufficient size and advanced technology just needs to harvest minerals. If our solar system is typical, we can expect massive amounts of these in asteroid belts, Kuiper belts, and in moons.

Time to travel : if the NASA scientists I quoted are correct, our speed will be 0.1 to 0.2c. If we assume 0.1c cruising speed, and 10 years to accelerate to that speed, plus another 10 to decelerate, the time to get to Alpha Centauri will be about 55 years.

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The earth wouldn't have to become very much hotter to significantly curb complex life forms. The upper limit for complex life is somewhere around 50C but that is for some very tough plants, animals need temps lower than that. Most of complex life on earth lives below 40C average.

Well, given that some animals are observed to withstand temperatures that high I'm pretty certain that there would still be a complex biosphere. But how long complex lifeforms will last on Earth will depend on how well the atmosphere will retain heat in the future; right now we are in a cool period, even though the sun is now brighter than it was in the distant past. Of course, after a certain point it won't matter. But I'm a bit reluctant to place the extinction of all life and complex life before half a billion years from now. I guess I will have to do more research in this area to be certain.

Terra forming is just a stop gag measure anyway you look at it. Self contained orbiting colony world/ships are the only way to go.

Why are they the only way to go? Each method has it's own advantages and disadvantages, and it's extremely unlikely that all the colonists will all choose to live on world ships, especially given the extraordinary high maintenance and engineering difficulties they pose.

No they only need star systems for raw materials, a properly build and maintained colony will provide everything humans need, including an ecology in huge ship spun for artificial gravity. Inside they would be like a valley on the Earth rolled up. They would not be sterile tin cans only to be used to travel in. People would live in them and have no knowledge of or need of planets.

Well, this does support my position. They are still dependent on star systems no matter what you do. Whether they decide settle down on planets or decide to be nomadic star travelers is moot. Either way, it will take a while before they decide to colonize other worlds. Although if they decide to stay in world ships, then their industrial and technological capabilities would be quite limited (which means that they might not decide to carry on the colonization process )

Star wisp type probes could be sent out ahead of the colony at very near C to report back about what lay ahead. If no suitable material was found in orbit around a star, unlikely that nothing would orbit a star, the colony ship could go one to the next star.

Using things like magnetic sails even a large colony/world ship could be sent to another star. using the stellar wind to accelerate and decelerate.

They will not land, they will simply go into orbit and start using asteroid/cometary material to build new ships and replace volatiles and other lost compounds. planets are not only not necessary they are not an easy source of materials and be avoided.

:confused:

How? You assert all this but you don't provide any basis, or take into the engineering difficulties inherent in this approach.

How would we ever be able to accelerate probes to near light speed. The best we've got so far, solar sails, will at most be able to accelerate an object to .1c at best, if we wanted to send a probe to the Alpha Centauri! And the craft proposed is a small probe. Any other method so far would take a preposterously large amount of fuel, be it nuclear or antimatter.

And you keep making the assertion that they will avoid planets. Why would they? Especially if they have a complex biosphere.

Name a land area that is harder to get to than the moon please.

I didn't only mean just land areas. For example, the bottom of the ocean trench. On the grand scheme of things, I've once heard that we know more about the moon then we do about our own oceans. And if you want a strip of land that is very difficult to inhabit, try looking up the Atacama Desert, as that area has been said to be comparable to walking on Mars (excluding the really low atmospheric pressures, of course).

We do not colonize these areas for good solid reasons, we cannot live there, an orbiting colony would be a much better place to live than Antarctica or the Sahara.

Aren't you contradicting yourself? You just claimed that it is easier to live in space than it is to live in any of the areas that I've just listed, which was precisely my point.

Most of the Earth surface is not suitable for human needs. Our colony world/ships will be great environments with controlled weather and 100% suitable for humans. since they will be controlled environments no need to worry about finding a place to live among the stars all we need is raw materials.

Most of the galaxy isn't either, and yet you claim that interstellar space is better than living on planets . Sure, they would be able to control the habitat inside the ship, but what about all those nasty high velocity asteroids or meteoroids? Or solar storms? Or radiation? Or even human error? Technology can only do so much, world ships aren't the universal panacea to our space colonization woes.

We would avoid areas where our ships couldn't protect us and planets are irrelevant.

Uh huh, sure. Try avoiding a solar flare or a supernova while your at it.

small ice worlds could be broken up for materials.

That would take up quite a bit of energy. The ice on Triton is harder than steel, and that's an ice world that is in our solar system. How would such a tiny ship, who has to devote most of it's resources to maintenance, be able to do that? Of course, you could go nearer to the star and find comets, but then you have all those other hazards to deal with that I listed.

But overall, for a system like that to work, they would, SURPRISE! be confined to the star system , which means that colonization of the galaxy is slowed down even more.

Because we wouldn't be occupying planets!

You keep asserting this, but don't provide any basis. Why wouldn't they? Don't you think that it's a bit unlikely that all colonists that spread out would decide to just simply stay in their world ships, especially if they find a very good Earth-Like planet? What about all the disadvantages of staying on the colony world ship?

Even 10 million years is a eye blink in terms of the galaxy, the only other option is to sit and wait for extinction.

True, but it's a lot longer than a few hundred thousand years. And we are not even sure if it will take that short a time, I've seen estimates run up to 50-100 million years. Even with FTL technology, should it be possible.

we need to get things going by pursuing the exploration and exploitation of our solar system now. a simple natural disaster could keep all of it from ever happening. Once we are in space and colonizing the asteroids it will be much more difficult to kill us all and we will take complex Earth life with us, if nothing else for food.

Don't get me wrong, I totally support space colonization, and I do think it is imperative. But don't think that this is a simple task, or that there is only one way to colonize the galaxy. You may be able to control your environment inside a world ship, but they also have disadvantages (e.g. limits industrial growth, limits population growth, space hazards, etc.). You can't have your cake and eat it too.

I do think that we as a species will eventually go out to colonize the galaxy, but I'm not holding my breath. It is going to take a LONG time before we conquer it.

Besides which, we greatly reduce the risk of extinction by just going out into Mars. And continue to do so the more worlds and star systems we colonize. Life on Earth has a good half a billion years to do it, so there is no need to panic right away.

A few points.

The polynesians took 12,000 years to colonise the Pacific, with the Maori reaching my country only 800 years ago.

12,000 years??? My sources claim that the Austronesian expansion started in historical times, with most estimates stating around 3000 - 2000 B.C.E. , out of Taiwan. That's a lot less than 12,000 years. And this particular site says that Polynesia itself was beginning to be colonized in as recently as 1000 B.C.E. : http://sscl.berkeley.edu/~oal/background/polyhist.htm

The reason they took so long was primitive technology, and tiny destinations separated by vast distances. Star travel will not be the same, since we can see our destination.

Your kidding, right? Do you have any idea of how big space is? Or how little we know about even our closest star systems? Colonizing the ocean is trivial compared to colonizing star systems. And "primitive" technology??? They had the ability to cross an ocean for thousands of years! They were a seafaring people while the Eurasian sailors were still trying to figure out how sail without staying in sight of land.

The Sahara desert is definitely lived in and fully colonised. It is just that its water supply is low meaning a low carrying capacity - thus low population.

Yeah, and all those fully colonized areas are near the ocean or the Nile river, or near an oasis, where there are fertile lands. It is uninhabited everywhere else.

The reason we do not live in Antarctica is international treaty. Inuits would have no problem living there. Indeed, neither would westerners, though they would be dependent on exploiting natural resources and trading for food.

Not really. If humans could have lived there, they probably would have already colonized it long ago, before the arrival of the Europeans.

The reason that Inuits and the Siberian tribes could live in Arctic climates is because they have access to reindeer and walruses, to give an example. Those animals could be used for both food and shelter, and most importantly warmth. However, you will notice that even those areas are very sparsely populated, and they are totally dependent on those animals for their own survival.

And then there's the fact that reaching Antarctica requires a boat (of which the cold climate and icebergs would have killed off any would be colonizers).

I agree with Moontanman in that humans will not need planets. And it is probable that most star systems will not have 'habitable' planets. Instead, we will live in massive space habitats, and harvest cometary debris and the like, for resources.

I don't agree with that at all, for the reasons listed above.

Humanity probably will have practical nuclear fusion energy within 100 years. By the time we leave our own star system in about 1000 years, it will be highly developed. With abundant fusion energy, a space habitat of sufficient size and advanced technology just needs to harvest minerals.

And fuel. And a stable biosphere. And protection from space hazards.

If our solar system is typical, we can expect massive amounts of these in asteroid belts, Kuiper belts, and in moons.

It depends on which part of the galaxy you are in.

Time to travel : if the NASA scientists I quoted are correct, our speed will be 0.1 to 0.2c. If we assume 0.1c cruising speed, and 10 years to accelerate to that speed, plus another 10 to decelerate, the time to get to Alpha Centauri will be about 55 years.

And that's the nearest star to the solar system.

Edited by I_Pwn_Crackpots
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My predictions:

1) Space, and the galaxy, will be colonized. While many people will be fine staying on earth, there will always be groups wanting to colonize and explore, and they will eventually do so unless they are prohibited and the prohibition enforced.

2) All mass in the solar systems colonized will be used. People will not simply live on 6,000,000,000,000,000,000,000 ton rocks with most of it sitting unused beneath their feet; at the very least people will dig down and live throughout it, not just on the surface. More likely, because of heat dissipation from high per capita energy usage, it will be split up into trillions or more orbiting colonies, as well as some faster colony ships. The star will eventually be mined for its hydrogen (for power) and whatever carbon it has (for building material). The star would either be extinguished, or a Dyson sphere of some sort built around it.

3) The earth will send the most colony ships of any planet, if only because it is where we start off from, and we would likely be able to build the ships faster than they can arrive. The vast majority of new colonies will be interested in starting new colonies, because the colonies would be founded by people who were interested in starting new colonies.

4) The colonization process will be slow. Even a 0.5c average speed (including building new colony ships) would likely be too high an estimate.

5) However, the colony ships sent out will not just be average habitation colonies that wanted to move out; they will be specially built for speed. They could still be large though.

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To Mr Skeptic

Just a small point. The maximum speed possible, according to current technology, is 0.2c, and even that is not terribly likely. Barring some breakthrough into currently unknown physics, 0.5c is simply fantasy.

To Mr Crackpots

Re extra-solar colonists staying off planets.

The problem with treating planets as destinations is the sheer difficulty of fighting gravity wells. Today we have an enormous problem getting people into space, with the need for incredibly expensive rockets to lift mass into space. The cost will be something like $10,000 per kg to get mass into orbit. If we start out with a massive space habitat that travels to another star system, and an Earth like planet is found, then they will colonise it. However, the chances are that whatever is found will be far from habitable. It makes good logical sense to think that the star travellers will regard the gravity well barrier as too much, if and when the planets they find are utterly hostile. Remember that these are guys that have been in space for decades. Space is their home. We can expect that any star system will have the equivalent of rings and small moons around gas giants, asteroid belts, Kuiper belts etc. In other words, lots of ice and rock fragments drifting in space. Harvesting them will be easy. No gravity wells to fight. They can be used to build new space habitats for their expanding population. Fuel is deuterium from the ice. The rest of the ice makes water and reaction mass. Rocky materials provide minerals. As long as the population stays in space, travel to further destinations is easy. Drop to a planet surface, and you have a real problem. The planet will almost certainly be hostile - wrong atmosphere, wrong temperature, wrong orbit etc. To live there would be similar to living in space, in that you would have to build habitats screened off by massive metal walls from the surrounds. The only advantage would be an abundance of rock and (hopefully) water or ice. However, I do not think that will be limiting when in space. To terraform a new planet would take thousands of years, and why should you bother? ##### Link to post ##### Share on other sites To Mr Skeptic Just a small point. The maximum speed possible, according to current technology, is 0.2c, and even that is not terribly likely. Barring some breakthrough into currently unknown physics, 0.5c is simply fantasy. That I do absolutely agree with. To Mr Crackpots Re extra-solar colonists staying off planets. The problem with treating planets as destinations is the sheer difficulty of fighting gravity wells. Today we have an enormous problem getting people into space, with the need for incredibly expensive rockets to lift mass into space. The cost will be something like$10,000 per kg to get mass into orbit.

It depends on a planet actually. If the planet is Earth sized, then there would be some difficultly, especially if the necessary resources to do so are scarce. But again, this is a factor to be taken into account in determining how long it will take to colonize a galaxy; if the planet is not that great, then you are not going to see much effort to continue the colonization process from that particular colony. And it's the same if you ultimately decide to just stay in space habitats, poor star systems=limited space colonization.

Not every space colony is going to be ideal, some will be better than others. I know it sucks but that's reality.

If we start out with a massive space habitat that travels to another star system, and an Earth like planet is found, then they will colonise it. However, the chances are that whatever is found will be far from habitable.

Well, that depends on how you define habitable, or qualified for colonization. Obviously gas giants and planets similar to Venus, or planets that have no water will be avoided.

But all that is necessary for habitation is that there is large amounts of water and a significant atmosphere, and maybe some hydrocarbons or lower than usual gravity. That's why we are contemplating and planning on colonizing Mars instead of Venus, even though Mars is utterly hostile to human life at the moment. Other immediate candidates include the moon, Europa and Titan.

It makes good logical sense to think that the star travellers will regard the gravity well barrier as too much, if and when the planets they find are utterly hostile.

See my note above.

Remember that these are guys that have been in space for decades. Space is their home.

Humanity has lived as hunter gatherers far, far longer than as anything else. And yet, within the past 10,000 years they were easily able to adopt a sedentary lifestyle. Even in historical times there are examples of bands and tribes settling down after spending thousands of years roaming the land. So I find it unlikely that humans spending mere decades on a ship would simply decide to adopt a nomadic lifestyle, unless they have absolutely no choice.

We can expect that any star system will have the equivalent of rings and small moons around gas giants, asteroid belts, Kuiper belts etc. In other words, lots of ice and rock fragments drifting in space.

Only in metal rich areas of the galactic plane. And, also, that is precisely the problem with space habitats as lots of rings, moons, etc. means lots of meteroids which would pelt the habitat to death.

Harvesting them will be easy. No gravity wells to fight.

What??? How would they be easy to harvest if you confine yourself to space ships??? No gravity doesn't gurantee that these materials will be easy to harvest.

They can be used to build new space habitats for their expanding population.

Expanding population? How would that ever materialise if they confine themselves to space ships? If they decide to just live in habitats, they will need effective birth control, and in general the population capacity would be quite low on a space habitat, as resources and space would be quite scarce.

Fuel is deuterium from the ice. The rest of the ice makes water and reaction mass. Rocky materials provide minerals.

True, but you haven't discussed how they could possibly develop a significant infrastructure necessary to extract them, if they confine themselves to space habitats. Also, only a small percentage of a given body will be usable for building material anyways, so that's another problem our would be nomadic space travelers would run into.

As long as the population stays in space, travel to further destinations is easy.

No it wouldn't. They are still dependent on the star system, so it is unlikely that they would have the necessary resources or motivation to continue the colonization of the galaxy. And the population growth just wouldn't be there.

Drop to a planet surface, and you have a real problem. The planet will almost certainly be hostile - wrong atmosphere, wrong temperature, wrong orbit etc. To live there would be similar to living in space, in that you would have to build habitats screened off by massive metal walls from the surrounds.

The only advantage would be an abundance of rock and (hopefully) water or ice. However, I do not think that will be limiting when in space.

And an atmosphere, which means protection from space objects and radiation. And an over abundance of potential resources, especially if the planet has a complex biosphere. And being close to the star means they have a viable energy source. And most importantly, they will landspace.

With all that, you can then have a large population and food surpluses. With a large population they could then develop industry, and with industry they can then build their own colony space ships. All that is not likely to happen if you confine yourself to a space habitat.

To terraform a new planet would take thousands of years, and why should you bother?

That depends on the planet though. It if is Earth-Like enough, then terraforming would be a trivial task.

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Here is the situation. A space colony ship has left Earth and gone to Alpha Centauri. With 10 years acceleration and deceleration time, and a cruising speed of 0.1c, it takes 55 years. The ship is now at its destination. You are the captain. You were born on board, 15 years after the ship left Earth making you a vigorous 40 years old, and you were elected captain when the old guy died of old age on board.

You look around the Alpha Centauri system, taking a few years to do it properly. You find a bunch of planets, and a whole lot of space debris. The only possible colonisable planet is similar to Mars. Cold. Toxic and very thin atmosphere. All the water tied up in very solid ice. A decision must be made. Do you, and the rest of the ship's complement, take on the whole business of colonising the planet, or do you stay in space, harvesting ice and debris to survive, and build more habitats in space so that the population may grow?

Remember, you and almost all the others, are not planet born. Virtually everyone knows nothing more than living inside a space habitat. That is home, and 'natural' to everyone.

To colonise the planet means parking in orbit around the planet, and shipping a small number of people down, to get them to set up a base. They have to harvest ice to refuel the lander craft for a second trip. They have to dig at least 10 metres under the planet's surface to set up underground habitats (if it is like Mars, the radiation levels at the surface will be long term lethal).

The rest of the people on board will have to wait years till enough living room and enough lander craft capacity permits them to go down and colonise. They will live lives no better than in space, since they cannot leave the underground habitats except for short trips in full space suits.

What do you decide? To commit to an unknown way of life with enormous restrictions, or continue to cruise around the planetary system, harvesting ice and minerals at need? Would you not be strongly tempted to continue with what you know best?

I discovered many years ago how easy it was to get useful material from rock. I worked for a company that made mineral fibre by melting basalt in an electric arc furnace, and blowing it into strands. A by product of this was pig iron, which they sold. The Earth's crust is 5% iron by weight, and iron is very common in meteorites. A space habitat society would have no problem harvesting iron in vast amounts. Remember that we are talking about a society 1000 years or more in the future. The technology they have access to will be awesome.

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They have to harvest ice to refuel the lander craft for a second trip.

Or just build a Space Elevator.

You could park your ship in a Geosynchronous orbit and drop down a tether towards the planet. Meanwhile a Lander and team is sent to planet to build the anchor on the planet.

Once this space elevator is built, getting into and out of the planet's gravity well is much simpler and you can use more varied methods of power generation to get people and resources into space.

Not only that, when going into space, it will take less energy because you don't have to haul your energy (fuel) source up with you, it can stay on the planet (or even remain in space) as you would only need electricity to run the motors and no longer need a rocket.

If you can build a Space Elevator, then colonisation becomes much easier.

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To Mr Skeptic

Just a small point. The maximum speed possible, according to current technology, is 0.2c, and even that is not terribly likely. Barring some breakthrough into currently unknown physics, 0.5c is simply fantasy.

Oops! I meant .05c, not 0.5c

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I think we should realize we are talking about this with everyone having a different idea of what is going on.

The space habitats I am thinking of would be torus' miles across, the inside would be open habitat with room for tens of thousands of people living under the surface of the inner surface of the torus. it would spin for gravity, probably the minimum gravity needed for healthy humans, lets say 1/4 gee just to have a set point. These habitats would move around slowly using magnetic sails and possibly nuclear powered ion drive when needed. magnetic sails can be tens if not hundreds of thousands of miles across, they get bigger when far away from the star and smaller as they approach so the average acceleration is similar when near enough to use stellar wind. Light sails are limited in size and dust corrodes them, they are hard to furl and unfurl, they are in no way comparable to magnetic sails. these habitats would be like rolling up section of the earth maybe ten miles across and 100 miles long (extreme example but you get the point) Possibly material strengths would limit the torus to much smaller or maybe allow even bigger, we don't know for sure how material construction will change. right now quite large structures could be built using carbon tubes and so forth. There is no limit to manufacturing in space that is not even more severely limited on a planets surface. so there is no reason to build anything on a planets surface. Going to another star and building these worlds/ships would be a slow process but as the colonies began to send out colonies the process of spreading humanity and complex life would speed up exponentially. planets would likely be ignored, the danger from the gravity well and exotic organisms might be a good reason to avoid planets altogether. these space habitats would be big enough to house wild life and forests (they wouldn't really be wild btu the effect would be the same) as well as humans. i am not talking about being couped up in a tin can or small cabin. by necessity there would be room for open spaces. Yes population would have to be controlled but that isn't necessarily a draw back at all. If your colony held 5000 people to start with and had a capacity of 25 thousand population control wouldn't have to as draconian as it would for a ship that only held 100 people. The available resources in space vastly out number the amounts available on a planetary surface. meteors could be controlled against by out current technology, even 100 years from now i would expect things like lasers, magnetic fields for charged particles and radar to pick up any dangerous meteors to exceed anything we could predict now.

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An advanced technology would have nothing to fear from meteors, since early detection systems would permit a very gentle sideways shove to make sure they miss.

Edtharan is correct in talking about space elevators. They would make planetary colonisation much, much easier. I still am a bit sceptical, though. A space elevator from stationary orbit to Earth would have to be 78,000 km long (The ship at 35,000 km and the ribbon extending in to and out from the ship), and wide enough that meteor impacts would only create a hole - not destroy it. How heavy would a very strong and wide 78,000 km ribbon be? I suspect that the weight would make it totally impractical to carry, even on a very large starship.

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How heavy would a very strong and wide 78,000 km ribbon be? I suspect that the weight would make it totally impractical to carry, even on a very large starship.

Well for strength, Carbon Nanotubes are nearly up to the task, so we might be able to make these things soon.

As for carting the raw materials around, well you do have a solar system to harvest from .

Carbon could either be harvested directly from comets and asteroids, or if the technology is sufficiently advanced, it could be manufactured using fusion.

I do. We may know where the stars are at, but we are pretty much in the same position as the Austronesians were when they left for the Pacific islands. We also don't know where to go, and before we decide on a star system we would have to send probes to gather information. Or just accept the risks and go to that star system anyway. At the very least, this doubles the time necessary to actually go out and make stable colonies on those star systems, even if we launch the probes ahead of time.

Actually we are finding planets around other stars now (even terrestrial planets) and this is with current technology and being in an atmosphere. In space we could make larger telescopes and produce swarms of them in a massive interferometer. Using these tools we would be able to analyse the atmosphere of planets orbiting another star (they are even attempting to do this today ).

We wouldn't have to send probes to nearby systems, nor blindly set out and hope for the best. We would know what the large bodies that make up the new solar system will be and even if they have a viable atmosphere for a colony (and maybe even if they harbour life). And this will be available to us within the next 50 years.

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I see lots of reasons why we cannot colonize space, a few that seem to think it might be done. Of the people who say we cannot do it then what should we do? Not try and go down with the ship? (Earth) Or should we prepare for the worst and try for the things that might be difficult but still with in the realms of possibility as we know it? Do we have any other choices to avoid the extinction of the human race?

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Assuming the survival and continued growth and development - especially technological - of the human species, it is only a matter of time before we develop close-to-self-sufficient space habitats. Once they are up there drifting about the solar system, it is only a matter of more time before, for some reason we cannot guess right now, one such habitat and its denizens decides to make for another star system. With the right strap on propulsion unit (solar sails and/or a linear particle accelerator), a massive speed, possibly 0.1c, could be reached and Alpha Centauri is only 55 years away.

Of course, it all depends on my initial assumption. Perhaps the LHC will make the black hole that will swallow the Earth. Bewaaaare. You have less than 6 months.

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It should be noted that we already have a self-sufficient (well, solar powered) space habitat.

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Mr Skeptic

Noted. However, we got a long way to go. The current space station cannot keep people healthy for too long. A long term habitat will need gravity, shielding from radiation, a nuclear fusion power plant, and enough green plants growing to remove CO2, provide oxygen, and grow food.

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Yes we will need gravity and a habitat with food and oxygen. Living on the inside surface of a torus spun for gravity and enclosed for atmosphere and lighted by either piped in sunlight or artificial light would be the way to go. the Trojan asteroids of Jupiter would seem to be the ideal place to build these space colonies.

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