Humanity has to stop being Human

[tharkûn]

Tharkun, nobody would leave on such terms, knowing that they could never come home and there would be no benefit at all for themselves. Also, you gotta figure that with the amount of time the colonists would have, they would probably be able to disarm the nukes. Either way, the resources required to send such a thing outsystem, and the energy required to get there would come from us, and I doubt that there's any reasonable amount of raw material to make up for the energy expidenture. Overall, nothing would be gained.

Sure there are such people - those who want adventure and those who would like their families to receive massive payouts. Utterly huge numbers of American immigrants migrated to America, never saw their relations again, yet sent money back to the old world. Worse comes to worst there is always less than voluntary methods - like drafts, criminal sentences, and slavery.

Even supposing the colonists could defeat whatever your most economical threat package happens to be, all you have to do is have a tradeoff where the threat costs less to you than if the colonists payout and the cost of circumventing the threat is greater to the colonists than if they payout.

When you include the ability to transmute elements, light elements are the only raw material to be required. Frankly I don't see what is so hard about sending out a robotic hydrogen harvestor to land on a moon like Titan, make a few megatons metal hyrdide, and send that off on a ballistic course to earth.

Once you have doable hydrogen fusion, even if it is an asteroid sized facility in orbit, you can get almost inexhaustible energy - suck Titan's atmosphere dry, mine the gas giants, or just sweep out the minute hydrogen traces throughout the solar system and surrounding local space. When you think about how much potential fusion energy there is even in Titan alone you realize that the type of economy that can sustain is mind boggling. With an energy base like that you can transmute elements that we find more economical to mine today and never run short of material. Really long before you run out of useful energy, the sun will have blown up.

[Patrick Degan]

Tharkun, nobody would leave on such terms, knowing that they could never come home and there would be no benefit at all for themselves. Also, you gotta figure that with the amount of time the colonists would have, they would probably be able to disarm the nukes. Either way, the resources required to send such a thing outsystem, and the energy required to get there would come from us, and I doubt that there's any reasonable amount of raw material to make up for the energy expidenture. Overall, nothing would be gained.

Sure there are such people - those who want adventure and those who would like their families to receive massive payouts. Utterly huge numbers of American immigrants migrated to America, never saw their relations again, yet sent money back to the old world. Worse comes to worst there is always less than voluntary methods - like drafts, criminal sentences, and slavery.

Excuse me, but you cannot seriously think there is a valid comparison between societies seperated by two months of ocean travel and two societies seperated by two decades (minimum) of interstellar travel.

Even supposing the colonists could defeat whatever your most economical threat package happens to be, all you have to do is have a tradeoff where the threat costs less to you than if the colonists payout and the cost of circumventing the threat is greater to the colonists than if they payout.

Excuse me, but what conceivable form of attack is going to scare colonists who know it's going to take decades to reach them and said time-lag therefore giving them plenty of time to counter it long before it ever comes within range? Do you not grasp just why any such scheme would be utterly ludicrous?

[Surlethe]

Your logic is severely flawed. The idea that two star systems light years apart would have some sort of imbalance in what they could produce with the resources available in either which one could make up for the other in trade is unrealistic on its face;

I'm convinced.

...nevermind the assumption that any sort of trading arrangement between star systems is feasible considering that there would be no way to shift any sufficent amount of material or goods across a distance requiring decades in the crossing to justify the engineering effort or the cost in fuel. Slower-than-light means that whatever civilisations spring up in other star systems as a result of mass space migrations will be wholly on their own, and they will be making do with what they've got, but that will be a considerable resource to draw upon.

I was operating under the assumption that since the system will meet their energy needs indefinitely (i.e., mining gas giants), they will eventually be able to construct ships for which it would be profitable to engage in trade with near colonies. I see the flaw in it now.

The atmospheres of gas-giant planets should suffice for such a supply into the indefinite future.

Even if they run out of that, they could still mine the star, right?

[Patrick Degan]

The atmospheres of gas-giant planets should suffice for such a supply into the indefinite future.

Even if they run out of that, they could still mine the star, right?

It would not be necessary. Hydrogen could be "cracked" from cometary ices and lighter elements which would still be quite abundant in the star system. The eventuality of resorting to those as primary sources for hydrogen, however, would not arise for several millions of years to say the least.

[lazerus]

This doesn't necessarily follow at all, unless in fact you're really talking about one-sided exploitation. Your assumption is dependent on the idea that the solar system would only pay in colonists, whereas Earth presumably has a lot of stuff with which it can trade. Otherwise, a trade union would make no sense; trade is generally conducted for mutual benefit.

Realistically, we'll most probably see such trade being conducted on a smaller scale within the solar system. Scaling it up shouldn't be all that impossible, at least in principle.

22 years minimum there and back dosn't make for very good trade in manufactured goods. By the time the shipment arrives, the colony could have made it on their own.

Two points.

1. "There and back" is irrelevant. "There" matters, but unless you send the goods back for a refund, you have no reason to return it.
2. Again, you presuppose something. In this case, it is that the wares consist of manufactured goods that the colony simply must have, with no consideration made in regards to the economical benefits of trade Needless to say, if it was easier to buy the goods than to manufacture on site, they would buy it. This is roughly the way a centralized industry works.

1) 22 years. 11 years to send the signal "Hey, we want to buy X". And another 11 years for X to arrive.

2) I challenge you to find a good that is so much cheaper to produce in one technologicly advanced system as compared to another that it's worth a 22 year wait and the insane shipping fees.

Actually, it would be far easier to simply build orbital habitats as needed to accomodate the growing population of Sol. There is plenty of space within the habitable zone of this star system and even in the inner and outer zones to accomodate thousands of artificial habitats without any of them orbiting on a collision course with one another or being impeded in the harvesting of solar energy.

However, space migration, when it finally does happen, can establish the same setup at any star with a sufficent energy-output. You don't even need Earthlike worlds if you can build orbital habitats using the minerals freely available from the asteroids and moons of the star system colonised by the initial band of migrants. But the idea that there would be anyone returning from the stars after leaving Earth in STL vessels taking decades in the crossing is neither feasible nor logical. Any new colonial society is not going to waste one of its valuable spacecraft in such a purposeless journey.

Exactly.

Unless it can't make it on its own, or its resources could be put to better use making something else to trade with the incoming ship.

Except that we are assumeing an incredably tech-advanced society. What makes Sol so speical that only it can produce something?

It ships part of its Q (manufactured or raw) to the colony, and receives part of the colony's Q in return. Because of the nature of trade, both have a higher Q than either would have before.

Uh.....no. You can never under any circumstances create more Q. Q is conserved. Besides, such trade would be pointless, see my above comments.

In the long run, the markets will still distribute Q efficiently. And in the long run, the people who value Q the most are the ones who will use it the most efficiently, because they want to get the most value out of the least amount of resources -- thus, they utilize Q efficiently. Thus, a free market distributes and uses Q efficiently.

No, not efficently, cheaply. In theroy, you would use coal the same way if it was amazingly rare, or if it was plentifull. But in reality, the chepaer it is the more people tend to waste.

Dyson spheres? If you can make a fucking Dyson sphere, you probably have hyper-advanced cryogenics and AIs. Hell, you can probably roboticize a human, and make him live for a thousand years. That's the only way I can think of to create an interstellar Empire. Even then, military response to Rebellion would be extremely delayed. An Empire might just be impossible.

That was........entirly irrelevant.

False. All you would need to do is establish a contract you send out the colony ship and in return they ship back a prespecified amount of raw materials and the colony is free and clear. In order to ensure compliance you launch nuclear missiles behind the ship which will disarm when they pass the large blocks of refined metal or whatever on a Sol-bound trajectory. As long as the colony has limited enough resources that they have no other option than to quickly process large amounts of whatever resource you desire, then compliance is assured.

Assuming 100% loyalty among the people placing the bomb. And 100% stupidity in the colonists engineers who will have 22 years to disarm it. Yeah. That's going to happen.

Not to mention that it's STILL a 22 year delay. Minimum.

Excuse me, but what conceivable form of attack is going to scare colonists who know it's going to take decades to reach them and said time-lag therefore giving them plenty of time to counter it long before it ever comes within range? Do you not grasp just why any such scheme would be utterly ludicrous?

Imangine trying to attack someone who has:
The home ground advantage
22 years foreknowledge of your attack
The fabrication system to build their own fleet
The ability to just pack up and leave if they don't think they can win.

Like you said, it's insane.

[Eleas]

1) 22 years. 11 years to send the signal "Hey, we want to buy X". And another 11 years for X to arrive.

2) I challenge you to find a good that is so much cheaper to produce in one technologicly advanced system as compared to another that it's worth a 22 year wait and the insane shipping fees.

1) You would almost certainly have to establish a supply train - in other words, determine that x is useful and is likely to be always useful. Ordering a single shipment was not what I had in mind.

2) Freely conceded. I wasn't really considering "shipping" per se, either - just flinging out the cargo in the desired direction, adjusted by microrockets if necessary, although that's probably unworkable. I certainly didn't propose manned shipments.

[lazerus]

1) You would almost certainly have to establish a supply train - in other words, determine that x is useful and is likely to be always useful. Ordering a single shipment was not what I had in mind.

The only resource that makes any sense as X is raw materials. Which we jsut established won't hapen.

[Eleas]

1) You would almost certainly have to establish a supply train - in other words, determine that x is useful and is likely to be always useful. Ordering a single shipment was not what I had in mind.

The only resource that makes any sense as X is raw materials. Which we jsut established won't hapen.

*nods* Agreed.

[SPOOFE]

Excuse me, but you cannot seriously think there is a valid comparison between societies seperated by two months of ocean travel and two societies seperated by two decades (minimum) of interstellar travel.

The difference becomes a lot less severe when you factor in increasing lifespans, either from improved medical technology, cryogenics, or cybernetics. If a person lives for several centuries, what's a couple decades?

[Zero]

Excuse me, but you cannot seriously think there is a valid comparison between societies seperated by two months of ocean travel and two societies seperated by two decades (minimum) of interstellar travel.

The difference becomes a lot less severe when you factor in increasing lifespans, either from improved medical technology, cryogenics, or cybernetics. If a person lives for several centuries, what's a couple decades?

Ever spent three days in a car? You'll probably live for 70 years, so what's three days? It's still uncomfy.

[tharkûn]

Assuming 100% loyalty among the people placing the bomb. And 100% stupidity in the colonists engineers who will have 22 years to disarm it. Yeah. That's going to happen.

No all you need to do is make it cheaper to send out the material you want that to detect incoming nukes, build defenses, and counter them. Seriously what is the only thing Sol could ever possibly want? Hydrogen. How much hydrogen is availible in a virgin solar system to send solward? Every damn comet for a start. All Sol wants is raw materials which can readily and easily be ejected from the solar system for a net energy gain to Sol and from the colonists point of view it is far cheaper to send a few megatons of ice solward than to build a functional NMD.

Not to mention that it's STILL a 22 year delay. Minimum.

So what? Pharma works with products on that type of delay on a regular basis TODAY.

Imangine trying to attack someone who has:
The home ground advantage
22 years foreknowledge of your attack
The fabrication system to build their own fleet
The ability to just pack up and leave if they don't think they can win.

Homeground advantage is nothing. You are in a virgin territory where attack can come from any direction. Think about all the problems of defending a two dimensional plot of ground from NMD attack, now go to 3D.

22 years assumes that the missiles will be launched only after the colony has failed to live up to its agreement. Instead you threaten to launch the missiles before the colony ship (longer transit time) and if they don't say see a solbound comet or 20 before they enter the target system's Oort cloud they arm up. The target is not going to have hardly any forewarning of when the missiles are due to arrive and any attempt to defeat them requires you devote significant resources to some type of NMD - which is going to be more costly than just sending out the ice.

The colony may have its own fabrication system, but frankly what is going to cost you more? Building a combat ready fleet or just sending ice to sol? The resource cost of the fleet is going to be far higher than just meeting your obligations to earth.

As far as packing up and leaving, sure and a large colony ship isn't going to glow brightly as it accelerates outsystem. Further we all know that a ship with a human crew can easily outrun missiles wich are scaled smaller and have less overhead

The truth is for a sufficiently advanced technology base, which one concerned about total energy availible in the solar system is going to be, the only raw material of real interest is going to be hydrogen and the cost of sending comets or whatever solward is ludicriously cheap when you have millions of years worth of unlimited energy in your new pristine solar system.

Ever spent three days in a car? You'll probably live for 70 years, so what's three days? It's still uncomfy.

Ever seen '3rd class' in some of the old cheap liners, let alone 'quarters' on 17th century ships? Uncomfy doesn't begin to describe it, people still spent weeks at a time in there.

Frankly I still don't see what is wrong with robotics. You build a small robot fleet that cruises interstellar space and close solar systems to extract hydrogen, convert to metal hyrdide and fire them off on a ballastic approach to Sol. Space is very forgiving to robots and you merely need to build them with decades worth of useful lifespan. Neither of the Pandora's boxes of self-replication or true AI are needed for something as easy and routine as hyrdogen collection.

[Zero]

Weeks at a time still doesn't come CLOSE to a timespan of 22 years, along with the absolute certainty that you'll never see anybody from home ever again. You keep making the analogy to ships, and colonization, but it's been demonstrated that it isn't at ALL the same thing.

[tharkûn]

Weeks at a time still doesn't come CLOSE to a timespan of 22 years

And a colony ship need only be a habitat with engines. Indeed if earth is in such dire needs of space/raw materials you might get more space and leisure on the ship than on the earths surface. Hell look at living conditions in Hong Kong today.

As far as never seeing anyone again, hell that was LUDICRIOUSLY common. Virtually NONE of the orginal American settlers ever went back across the oceon. Virtually NO ONE who took up the Oregon trail ever expected to come back to the midwest. One way immigration was ridiciously common in past history.

You keep making the analogy to ships, and colonization, but it's been demonstrated that it isn't at ALL the same thing.

You keep ignoring the fact that earth can harvest hyrdogen with robots and have an effectively infinite supply of fuel, further on the timescale it takes to deplete the useful energy potential of the solar system - the sun will FRIGGING EXPLODE first.

No I'm not saying that ships crossing the atlantic are perfect analogies to ships crossing the interstellar void, however HUMAN PYSCOLOGY hasn't changed. Immigration without hope of return? It's happened before, happens today, and will happen in the future the only difference is the reason why - cost, politics, or physics. Doing work to benifit the people you've left behind? Happened before will happen again. You've made some demonstrably wrong suppositions about human pyscology, things you say people won't do - which they have done countless times throughout history - deal with it.

Frankly I've yet to hear a single reason why humanity cannot exist indefinately as either nomads in massively large, yet blindingly slow habitats or using robotics to harvest hydrogen and ship it home in a decade or thirty.

[SPOOFE]

Ever spent three days in a car? You'll probably live for 70 years, so what's three days? It's still uncomfy.

I certainly hope the colony ships we send to the stars are significantly larger than a car. You ever spend three days in a house? Not necessarily all that bad, is it?

[Eleas]

Ever spent three days in a car? You'll probably live for 70 years, so what's three days? It's still uncomfy.

I certainly hope the colony ships we send to the stars are significantly larger than a car. You ever spend three days in a house? Not necessarily all that bad, is it?

Crammed in together with who knows how many other people, it can be damned annoying. And in spacecraft or space station, we can assume space will always be at a premium.

[tharkûn]

Crammed in together with who knows how many other people, it can be damned annoying. And in spacecraft or space station, we can assume space will always be at a premium.

Oh please have you ever seen Hong Kong? You can cram massive amounts of humanity into very small spaces without everyone going insane. It is only within the last century (*maybe* two) that the average individual travelled more than 20 km from his place of birth in his entire lifetime.

Space will not be at premium, mass will be the limiting constraint. A densley packed sphere or poorly pack cylinder require the same propellant mass to move. There is no upper limit for the size of a "spaceship" so long as you are willing to cut thrust accordingly (which adds to transit time to some degree).

For instance the "space nomads" concept doesn't require a sleek ship capable of fast acceleration and short times between stars; instead it requires you take a habitat, put some engines on it, and run them slowly if continiously. Frankly there is zero reason to suppose that a mobile habitat will have a significantly higher space premium than an orbital habitat.

[Eleas]

Crammed in together with who knows how many other people, it can be damned annoying. And in spacecraft or space station, we can assume space will always be at a premium.

Oh please have you ever seen Hong Kong? You can cram massive amounts of humanity into very small spaces without everyone going insane. It is only within the last century (*maybe* two) that the average individual travelled more than 20 km from his place of birth in his entire lifetime.

No, I haven't been to Hong Kong. However, the fact is, while human beings can live together in tight confines for extended periods of time, they usually choose not to.

Space will not be at premium, mass will be the limiting constraint. A densley packed sphere or poorly pack cylinder require the same propellant mass to move. There is no upper limit for the size of a "spaceship" so long as you are willing to cut thrust accordingly (which adds to transit time to some degree).

The bigger a spaceship is, the sturdier its construction must be for a given amount of thrust, which means more mass. And there comes a level where the thrust is so slow that travel time is effectively irrelevant. At that point, you might as well stay within the safe confines of whatever solar system you're in.

For instance the "space nomads" concept doesn't require a sleek ship capable of fast acceleration and short times between stars; instead it requires you take a habitat, put some engines on it, and run them slowly if continiously. Frankly there is zero reason to suppose that a mobile habitat will have a significantly higher space premium than an orbital habitat.

Yes, but we were discussing a colony ship, i.e. a vessel whose primary function was to reach another star system, not serve as a habitat in itself. Otherwise, what need would there be to colonize in the first place?

[tharkûn]

No, I haven't been to Hong Kong. However, the fact is, while human beings can live together in tight confines for extended periods of time, they usually choose not to.

Usually humanity has clustered in extremely small villages and never ventured more than 20 km from said cluster for hundreds of years. Went given the choice between the wide open spaces of the country, like say Montana, and packing themselves into the cities in search of a higher standard of living humanity has chosen to go for the higher standard of living every single time.

The bigger a spaceship is, the sturdier its construction must be for a given amount of thrust, which means more mass. And there comes a level where the thrust is so slow that travel time is effectively irrelevant. At that point, you might as well stay within the safe confines of whatever solar system you're in.

The point where thrust is so low comes very late in the game. Current ion engines have all the thrust of a sheet of paper's weight. The rocketry equations are quite forgiving for long voyages with slow acceleration. There is no reason a spaceship measuring kilometers in each direction couldn't be built by a sufficiently advanced society.

Yes, but we were discussing a colony ship, i.e. a vessel whose primary function was to reach another star system, not serve as a habitat in itself. Otherwise, what need would there be to colonize in the first place?

No we, or at least I, was discussing:

"The point that I am (rather clumisly) trying to come too is that long-term human existance is an impossiblity. For any prayer of an existance beyond migrating from system to system, with a few of us jumping shim from that system right before it dies, humanities basic nature has to change. "

Long term human existance isn't an impossibility. Build large scale habitats with engines that have burn times in the decades/centuries and low thrust. Hop from system to system, sucking up all the useable hydrogen in the system, transmute it through fusion and other nuclear reactions to get all your raw materials, build daughter ships, expand ever outward to till you hit the edge of the galaxy.

Or opt to stay in Sol and send out simple robotics to bring back hydrogen thus increasing Q.

Long term human existance is not impossible. Sure some preferences may change, some habits will go the way of the dodo, and customs will radically alter. So what? All that has been happening since time immemoral. Frankly I see no reason why some space age Moken type existance isn't possible. Travel the stars, set up temporary facilities in a new solar system, harvest that solar system, and return to the void.

[Patrick Degan]

Assuming 100% loyalty among the people placing the bomb. And 100% stupidity in the colonists engineers who will have 22 years to disarm it. Yeah. That's going to happen.

No all you need to do is make it cheaper to send out the material you want that to detect incoming nukes, build defenses, and counter them.

Nukes? You actually imagine nukes would be effective? After a two-decade flight through interstellar space? Long after the point when the fissionable componnents would have decayed from chemical corrosion to uselessness and the lithium-deuteride in the cores would have completely deterioriated?

Somehow, I don't think the colonists in the other star system are going to be shitting themselves over the eventual arrival of a bunch of duds.

Seriously what is the only thing Sol could ever possibly want? Hydrogen. How much hydrogen is availible in a virgin solar system to send solward? Every damn comet for a start. All Sol wants is raw materials which can readily and easily be ejected from the solar system for a net energy gain to Sol and from the colonists point of view it is far cheaper to send a few megatons of ice solward than to build a functional NMD.

Riiiight... because there couldn't possibly be enough hydrogen to be had from the atmospheres of the four gas-giant planets of our own solar system —not to mention "every damn comet" in the Oort Cloud.

Not to mention that it's STILL a 22 year delay. Minimum.

So what? Pharma works with products on that type of delay on a regular basis TODAY.

Which has exactly what relevance to the laughable idea of attacking another star system with STL nukes? Oh, that's right —none at all.

Imangine trying to attack someone who has:
The home ground advantage
22 years foreknowledge of your attack
The fabrication system to build their own fleet
The ability to just pack up and leave if they don't think they can win.

Homeground advantage is nothing. You are in a virgin territory where attack can come from any direction. Think about all the problems of defending a two dimensional plot of ground from NMD attack, now go to 3D.

Excuse me but are you insane? Exactly how would Earth get nukes to positions where they could attack from any vector other than straight from the direction of Sol? After a flight of two decades? Nevermind the trifling problem that the warheads will all be useless before they even get to the target.

22 years assumes that the missiles will be launched only after the colony has failed to live up to its agreement. Instead you threaten to launch the missiles before the colony ship (longer transit time) and if they don't say see a solbound comet or 20 before they enter the target system's Oort cloud they arm up. The target is not going to have hardly any forewarning of when the missiles are due to arrive and any attempt to defeat them requires you devote significant resources to some type of NMD - which is going to be more costly than just sending out the ice.

Um, no —twenty two years would be the flight-time for the missiles, whose warheads will all have been rendered useless duds thanks to the mechanics of chemical corrosion and decay.

The colony may have its own fabrication system, but frankly what is going to cost you more? Building a combat ready fleet or just sending ice to sol? The resource cost of the fleet is going to be far higher than just meeting your obligations to earth.

Or, the colonists simply end up wondering what Earth hoped to accomplish by sending a bunch of dud warheads their way.

As far as packing up and leaving, sure and a large colony ship isn't going to glow brightly as it accelerates outsystem. Further we all know that a ship with a human crew can easily outrun missiles wich are scaled smaller and have less overhead

You mean those missiles with the dud warheads which, BTW, would have expended all their fuel on the flight and would have nothing left for any additional acceleration to catch a ship with a full fuel reserve and more powerful engines?

The truth is for a sufficiently advanced technology base, which one concerned about total energy availible in the solar system is going to be, the only raw material of real interest is going to be hydrogen and the cost of sending comets or whatever solward is ludicriously cheap when you have millions of years worth of unlimited energy in your new pristine solar system.

Because the Sol system won't have millions of years of unlimited energy within its own boundaries? I hate to break it to you, but the very argument you're trying to float here in and of itself defeats your overall premise. The very resources Earth allegedly has to hold a colony light-years in the distance up for ransom already exist in abundance in Earth's own solar system, which is the primary reason why the scheme makes no sense whatsoever.

Seriously, Tharkie, put down the crack-pipe.

[SPOOFE]

Crammed in together with who knows how many other people, it can be damned annoying.

It can be. I fail to see how "can" constitutes absolute proof, however. What stops future societies from simply making bigger ships?

My point is that there is no technical limitation. Any point you bring up has a very plausible counter. Cramped quarters? Bigger ship. Crew stress? Virtual reality. Too much time? Improved lifespan.

So what else is left?

[Zero]

Getting those people into orbit is a difficult task. It's not as if such things are easy.

[Surlethe]

Getting those people into orbit is a difficult task. It's not as if such things are easy.

Remember, we have the resources of an entire system at our beck. His point is, since the system's resources are, for all intents and purposes, unlimited, difficulty is really no barrier.

[lazerus]

No all you need to do is make it cheaper to send out the material you want that to detect incoming nukes, build defenses, and counter them. Seriously what is the only thing Sol could ever possibly want? Hydrogen. How much hydrogen is availible in a virgin solar system to send solward? Every damn comet for a start. All Sol wants is raw materials which can readily and easily be ejected from the solar system for a net energy gain to Sol and from the colonists point of view it is far cheaper to send a few megatons of ice solward than to build a functional NMD.

Heh.......yeah. Because "bowing down is more logical then war" is how humans have always thought in the past, besides..


Nukes? You actually imagine nukes would be effective? After a two-decade flight through interstellar space? Long after the point when the fissionable componnents would have decayed from chemical corrosion to uselessness and the lithium-deuteride in the cores would have completely deterioriated?

Somehow, I don't think the colonists in the other star system are going to be shitting themselves over the eventual arrival of a bunch of duds.

Homeground advantage is nothing. You are in a virgin territory where attack can come from any direction. Think about all the problems of defending a two dimensional plot of ground from NMD attack, now go to 3D.

Except that any incoming ships will be visible long before they arrive.

[Zero]

Getting those people into orbit is a difficult task. It's not as if such things are easy.

Remember, we have the resources of an entire system at our beck. His point is, since the system's resources are, for all intents and purposes, unlimited, difficulty is really no barrier.

Are you going to claim to me that it's no problem at all, the extreme energy concerns? Hell, for getting that many people into orbit, I'd expect the energy output to have a significant change on the temperature of the earth's atmosphere. If resources are infinite, why do we care to leave anyways?

[Eleas]

It can be. I fail to see how "can" constitutes absolute proof, however. What stops future societies from simply making bigger ships?

My point is that there is no technical limitation. Any point you bring up has a very plausible counter. Cramped quarters? Bigger ship. Crew stress? Virtual reality. Too much time? Improved lifespan.

So what else is left?

When you have all these technologies to play with, the reasons for traveling seem almost arbitrary. My point is, using that argument, you could just as well spend your life hooked into a VR network, supervised by robots and systems calculated to be as resource efficient as possible.

But a slow journey like the one you described does seem like an interesting way to live.