Plausible limits of population [now playing: outer space]

[KathTheDragon]

Except you'd probably still be reliant on the surface for fresh air and water. Why waste energy recycling it, when you have a colossal store just a tunnel away? It doesn't make much sense to horribly pollute it.

I guess it all depends on how you perceive humanity. I am somewhat optimistic that the Oil Wars, when they get around to coming it whatever guise they take, will wake humanity up.

[Drydic]

Humanity will not survive if it limits itself to one single world.

[Torco]

ultimately humanity will not survive. All ends, we're not gonna be the exception
but yeah, colonizing a bunch of worlds will probably increase our life expectancy

[Herr Dunkel]

Ultimately, either shall humanity go extinct, or it shall evolve beyond the point where we won't be able to call it humanity

[chris_notts]

I think a lot of these limits are delusional. Working in the energy industry, I'm very familiar with the 'we could power the whole world just with solar panels in the Sahara!' type argument that people with some basic mathematical ability and extreme optimism about technology make. But in the real world these things don't work out because of one or more of the following:

(1) they require things to happen that violate the laws of physics

Lots of proposals to save the world seem to require the laws of thermodynamics to be suspended, which is a little bit worrying. Like economists who believe that efficiency is something that can be improved for ever, rather than a process of diminishing returns since for physical processes you cannot get out more than you put in, and on top of that:

(i) your new efficient setup typically requires more coordination, and eventually the costs of the bureaucracy overwhelms the savings
(ii) the most efficient setup is also the least robust, since robustness involves leaving slack in the system. As soon as your efficient system is hit by an unexpected shock it is likely to go down to be replaced by a much less efficient system (no system at all).

(2) they exceed the supply of required raw materials if scaled up to the proposed level

For example, high efficiency solar panels use rare earth elements, and a lot of other miracle technologies like high energy density batteries seem to involve the use of expensive elements or compounds with a limited supply. At this point people jump in with the 'human ingenuity is infinite' argument, which is of course a simple extrapolation from 100 years of success in 50,000 years of modern human history. And even in that 100 years we've failed to solve all of our problems with technology without creating bigger long-term problems in the process.

(3) they require politically impossible decisions to be made

If only everyone would join hands and sing kumbaya and share and think of the children...

(4) they produce unacknowledged waste or side-effects - either in production of the miracle technology that's supposed going to save us all, or in its operation.

For example, what impact on the climate do you think moving around that energy will have? Suppose we store lots of solar energy in the tropics, ship it to energy hungry countries closer to the poles (e.g. my home country of England) and then use it (= convert it into low grade waste heat)? Especially if we scale up global population one hundred times at the same time and move everyone to the same level of energy use as Westerners. Solar energy is not wasted: its distribution is a vital input into the world's climatic system, which is too big and complicated for even directed human intervention to produce predictable outcomes. And since human action is much more likely to be undirected and chaotic...

Of course, someone will point out that we might still only be moving around a few percent of the total energy, but then again human CO2 emissions are only a small percentage of naturally generated and absorbed CO2. But if that small percentage exceeds the capacity of the sinks, or if humans are at the same time busy demolishing those sinks and reducing their capacity, then you still have a problem.

(5) they have unacknowledged inputs that are depleted in their use

Modern industrial farming is a good example, since in its most common form it causes topsoil erosion, nutrient depletion, and requires a significant energy subsidy from fossil fuels to compensate for its short-term profitable but long-term destructive behaviour. This is why turning crops into ethanol makes no sense from an energy point of view, because the energy content of the fossil fuels used to produce the ethanol exceed (according to many studies) the energy content of the end product.

If it is possible to hit 1 trillion humans, then it would happen only briefly before complete population collapse and a reversion to an age where weeds, insects and microorganisms are the dominant form of life. I don't believe we have the capacity to manage the system in any kind of stable way if we grow big enough that it needs to be managed, rather than simply relying on in-built negative feedback loops to do the job for us. As soon as we overwhelm those feedback loops, which we are already doing in some ways, we are doomed as a species of 6 or 9 billion, although probably we will not be wiped out completely for quite a while yet. I can't believe that this idea that we can somehow decouple from the natural environment completely is anything more than a fantasy.

What we need in reality is not theoretical limits that always turn out to be excessively optimistic, but to place highly conservative limits on human environmental impacts and only slowly raise them while observing the effects. Instead of 'I think this will work so let's do it and see!' we need to avoid doing things until we are sure they won't do harm. Since until now our species has not shown the long-sightedness or ability to cooperate to do that, I am very pessimistic about the long-term future. I just hope the shit doesn't hit the fan until my time on this ball of rock is over.

EDIT: In answer to the question, it depends on the level of existence your people are willing to tolerate. Assuming you want long-term stability (i.e. no population collapse a century down the road) and everyone to have a Western standard of living, I would say the number is smaller than the current global population. This is based on my belief that even if there is a theoretical way to manage the Earth for more (which seems uncertain to me), and assuming that we completely took over all functions and services which are now provided by nature, we lack the cooperative and organisational capacity to reach that theoretical stable state and stay there. The success of high density small islands civilisations that have managed the trick is normally down to a combination of a much lower standard of living, strict population control, strict control of actions which might destabilise the system, and a small enough society that everyone knows everyone else. The small society aspect enables the control that is required for long-term stability. Can 20 billion humans be controlled in that way?

[Salmoneus]

OK, I'll bite. How much light do we actually need? If humans spend 8 hours in total darkness, and the other 16 hours using indoor light, then the vast majority of sunlight that falls on the Earth is superfluous. We could just cover the entire surface of the planet in solar panels, and use some of the resulting electricity to light our homes, including a handful of "sunlight" rooms where you can go and pretend to be on a beach. The plants will die, but as long as our machines can make amino acids more efficiently than plants, that's irrelevant. The entire net insolation can be used for electricity, 174 petawatts according to Wikipedia. At 20% efficiency (typical for top quality solar panels), you could provide American levels of energy consumption to 25 trillion people (that's 25*10^12).

I don't think that wikipedia figure is aligned with other wikipedia figures. But anyway, that ignores that half of the insolation doesn't reach the surface, and that two-thirds of what does falls on the oceans (which in this model we've dedicated to our farming). On the other hand, 20% efficiency is incredibly conservative.

So, as I've said above, my back-of-envelope is one trillion.

EDIT: that's not meant to be a hard threshold. Maybe if sunlight is closer to your figures and we have backup resources maybe we can get several trillion. More likely (I think) if energy use per individual is much higher than modern america, we can only get several hundred billion. The idea is more that one trillion is an edge of the envelope - if your Earth has anything like that many people, let alone more than that, then you're right on the edge of what is even possible, let alone probable.

[Salmoneus]

Except in order to maintain life on a planet entirely covered with solar panels you'd need a bit more than current american energy consumption. I mean just to make food for a person you need 3kw/h per day <at perfect efficiency> or 300kw/h <at 1% efficiency, like plants>. Also,moving around the water and the food and blablabla. I think that grants lowering the estimate from 2e13 to somewhere between 2e11~2e12

In pure terms, the earth has 1e32 joules of heat, and most of it is renewable as it comes from radioactive decay.a *lot* of energy can come from geothermal, if the tech be available.

Nope, geothermal not very useful at all. Total heat transfer from inside earth to the surface is apparently only twice current power usage. Most of that isn't practical to harvest (a huge area of rock very slightly raised in temperature isn't much use for energy production - you need the energy to be concentrated). Apparently upper estimates for geothermal top out around two terawatts, which is trivial (on the trillion-person scale), and even that is based on drilling miles and miles into the ground. Of course we can get more energy if we dig bigger holes - but of course, boring through solid rock and then extracting that rock kind of requires a fair amount of energy itself.

[Salmoneus]

I think a lot of these limits are delusional. Working in the energy industry, I'm very familiar with the 'we could power the whole world just with solar panels in the Sahara!' type argument that people with some basic mathematical ability and extreme optimism about technology make. But in the real world these things don't work out because of one or more of the following:

(1) they require things to happen that violate the laws of physics

Lots of proposals to save the world seem to require the laws of thermodynamics to be suspended, which is a little bit worrying.

Who are you talking about exactly?

(2) they exceed the supply of required raw materials if scaled up to the proposed level

This is a fair point. But assuming that photovoltaics will necessarily require the same materials in the future is itself highly tendentious - it's just putting a limit for the sake of putting a limit. Indeed, when we say 'photovoltaics' we don't even necessarily mean photovoltaics, just some form of solar power, and we already have solar power that doesn't require rare eaths - not as efficient, maybe, but the technology might improve, and in any case I was using a very conservative estimate for efficiency (i.e. assuming no improvement ever from now on).

The rarity of some materials is not something that affects the upper bound, I don't think, only the likelihood of reaching that upper bound. It also assumes no exploitation of extraterrestrial resources - now sure, we're assuming that all the energy comes from earth, but that's different from saying that we can't get any resources at all from off-earth.

(3) they require politically impossible decisions to be made
If only everyone would join hands and sing kumbaya and share and think of the children...

As a politics student, I'll point out that nobody has ever looked good predicting what will and won't be politically impossible even years into the future, let alone millennia. In any case, I don't really see what's even politically difficult about putting solar panels on our roofs.

(4) they produce unacknowledged waste or side-effects - either in production of the miracle technology that's supposed going to save us all, or in its operation.

For example, what impact on the climate do you think moving around that energy will have? Suppose we store lots of solar energy in the tropics, ship it to energy hungry countries closer to the poles (e.g. my home country of England) and then use it (= convert it into low grade waste heat)? Especially if we scale up global population one hundred times at the same time and move everyone to the same level of energy use as Westerners. Solar energy is not wasted: its distribution is a vital input into the world's climatic system, which is too big and complicated for even directed human intervention to produce predictable outcomes. And since human action is much more likely to be undirected and chaotic...

But again: why should anyone care? I mean, don't get me wrong, I'm all in favour of "nature". But we don't need it. If you're living in your subterranean air-conditioned city, why do you care what the weather is outside? Problems only begin once you move into a venusian hell-world. But thinking that these solar panels and the cities they support will automatically necessarily produce a venusian hell-world (and that there's nothing humanity could possibly do to stop it) is again pessimism for the sake of pessimism

(5) they have unacknowledged inputs that are depleted in their use

Modern industrial farming is a good example, since in its most common form it causes topsoil erosion, nutrient depletion, and requires a significant energy subsidy from fossil fuels to compensate for its short-term profitable but long-term destructive behaviour. This is why turning crops into ethanol makes no sense from an energy point of view, because the energy content of the fossil fuels used to produce the ethanol exceed (according to many studies) the energy content of the end product.

So? How is that relevant? We've coated the entire land surface of the world in solar factories, clearly we're not using 'modern farming' anymore. If you're just using that as an example and your point is that there MIGHT be some other reason why this is all impossible but you can't think of it, then sure... or there might not.

If it is possible to hit 1 trillion humans, then it would happen only briefly before complete population collapse and a reversion to an age where weeds, insects and microorganisms are the dominant form of life. I don't believe we have the capacity to manage the system in any kind of stable way if we grow big enough that it needs to be managed, rather than simply relying on in-built negative feedback loops to do the job for us. As soon as we overwhelm those feedback loops, which we are already doing in some ways, we are doomed as a species of 6 or 9 billion, although probably we will not be wiped out completely for quite a while yet. I can't believe that this idea that we can somehow decouple from the natural environment completely is anything more than a fantasy.

And I can't believe that this idea that we're all burdened by some original sin that will inevitably bring about our entire destruction and there's no way out unless we more piously respect the great goddes Gaia is anything but a fantasy.

What we need in reality is not theoretical limits that always turn out to be excessively optimistic, but to place highly conservative limits on human environmental impacts and only slowly raise them while observing the effects. Instead of 'I think this will work so let's do it and see!' we need to avoid doing things until we are sure they won't do harm.

Wait, you mean I SHOULDN'T go and cover the world in solar cells next tuesday, unless I've done a full health and safety analysis? Darn, my plans are ruined now!
However, since we're actually just a bunch of people thinking out loud about what might or might not be the case hundreds or thousands of years from now, for the purposes of plausible fiction, rather than actually being policy makers, I don't see that this objection is relevant to the thread.

Since until now our species has not shown the long-sightedness or ability to cooperate to do that, I am very pessimistic about the long-term future. I just hope the shit doesn't hit the fan until my time on this ball of rock is over.

EDIT: In answer to the question, it depends on the level of existence your people are willing to tolerate. Assuming you want long-term stability (i.e. no population collapse a century down the road) and everyone to have a Western standard of living, I would say the number is smaller than the current global population. This is based on my belief that even if there is a theoretical way to manage the Earth for more (which seems uncertain to me), and assuming that we completely took over all functions and services which are now provided by nature, we lack the cooperative and organisational capacity to reach that theoretical stable state and stay there. The success of high density small islands civilisations that have managed the trick is normally down to a combination of a much lower standard of living, strict population control, strict control of actions which might destabilise the system, and a small enough society that everyone knows everyone else. The small society aspect enables the control that is required for long-term stability. Can 20 billion humans be controlled in that way?

Some people like to fantasise about how everyone will be dooooomed I tell you, doooomed. But this is no more realistic than the opposite fantasy, that we needn't worry about anything because everything will be OK. The belief that "it's ok because humans can solve any problem" and that "it's not ok, because humans will never be able to solve these problems (because of original sin)" are equally much just statements of faith.

I wouldn't put too much money on humanity's inherent inability to cooperate (the more fashionable term for 'sin' these days!). Ask a man from a hunter-gatherer tribe thousands of years ago, where societies were numbered in tens and a sixth of everybody was eventually murdered, whether 21st century new york was within the limits of humanity's ability to cooperate and organise.

[chris_notts]

Wait, you mean I SHOULDN'T go and cover the world in solar cells next tuesday, unless I've done a full health and safety analysis? Darn, my plans are ruined now!
However, since we're actually just a bunch of people thinking out loud about what might or might not be the case hundreds or thousands of years from now, for the purposes of plausible fiction, rather than actually being policy makers, I don't see that this objection is relevant to the thread.

Since until now our species has not shown the long-sightedness or ability to cooperate to do that, I am very pessimistic about the long-term future. I just hope the shit doesn't hit the fan until my time on this ball of rock is over.

The key word is the word plausible in the title. Sure, it might be possible to have a stable population of 100 billion. But my post was an attempt to describe why I believed the probability to be extremely low. I won't deny it's possible that I'm wrong, but based on what I know right now it's implausible in the sense of there being a very small probability of getting there, not implausible in the sense that I can prove with 100% confidence that it is absolutely impossible in every sense. I don't think there's very much at all about the world that anyone can state they know with 100% certainty about the future.

Of course, that shouldn't stop you stick 100 billion in underground cavern cities if that's what you want to do in your conworld, in the same way that you should feel free to have fairies in your conworld or faster than light travel if that's what you want to do, but if you do that I don't think that 'plausible in the real world' is a fitting description for the result.

[Salmoneus]

But you imply that the probability is very small, to the point of being 'delusional'. If someone says "I think X is an upper bound of what might possibly be plausible maybe" and someone else says "you're delusional", it's hard to read that as actually saying "yes, you're correct, but I think it worth mentioning that more likely than not this won't actually happen".

[Btw, good to see you around here again]

[KathTheDragon]

But you imply that the probability is very small, to the point of being 'delusional'. If someone says "I think X is an upper bound of what might possibly be plausible maybe" and someone else says "you're delusional", it's hard to read that as actually saying "yes, you're correct, but I think it worth mentioning that more likely than not this won't actually happen".

[Btw, good to see you around here again]

The problem here is that nowhere did he say "You're delusional". You're reading something that simply isn't there. He is saying that it's possible, but he is simply of the opinion that it's unlikely to happen. 'Tis all.

[Salmoneus]

But you imply that the probability is very small, to the point of being 'delusional'. If someone says "I think X is an upper bound of what might possibly be plausible maybe" and someone else says "you're delusional", it's hard to read that as actually saying "yes, you're correct, but I think it worth mentioning that more likely than not this won't actually happen".

[Btw, good to see you around here again]

The problem here is that nowhere did he say "You're delusional". You're reading something that simply isn't there. He is saying that it's possible, but he is simply of the opinion that it's unlikely to happen. 'Tis all.

Well, he said that the limits we were proposing were delusional. As ideas can't have delusions themselves, this is commonly interpreted as a metonymy for thinking that having those ideas is delusional (and that the ideas themselves are delusions).

I would hope we would all agree that the scenario is improbable. That's different, however, from whether it is implausible.

[KathTheDragon]

A scenario is highly improbably if it is implausible. That is not to say that it is impossible, as we cannot predict the future that far ahead in any way, shape or form.

[brandrinn]

But anyway, that ignores that half of the insolation doesn't reach the surface, and that two-thirds of what does falls on the oceans (which in this model we've dedicated to our farming). On the other hand, 20% efficiency is incredibly conservative.

Surprisingly, that's not the case! About 30% of total insolation either doesn't reach the surface or is reflected away, but this is irrelevant because the Wikipedia figure is for total solar energy that reaches the surface*. Therefore, light reflected by clouds is irrelevant. Light reflected by solar panels is relevant, but this would be included in the figures given on solar panel efficiency, so it's dealt with. Ordinary panels you buy at the store are rated at 11%, but some products I've seen online advertize 22% efficiency. Even if these are lies, it's clear that 20% is not outrageous for a future society with advanced technology. And I was assuming we cover the ocean, too, but we could leave them for farming if you prefer. There is, as far as I can see, no consistent "our scenario" in this thread, though we could cooperatively make one after we're done bouncing ideas around.

*As you said, this figure could be dead wrong, but if that's the case we can just adjust it.

[Torco]

Even if geothermal isn't relevant here, and enough future tech might well make it so, there's still fusion... okay, that one might exhaust earth's water concievably, but its still available power.

...points....

Yeah, those are all challenges a society much more populous that us would face; however you're still looking at it from the perspective of desirability and oughts: again, no one will choose for there to be 8, 12, 16, 23, 41, 67, 123 or 400 billion people, there'll just *be* that many people, and the system will either have to adapt <lowering energy consumption, increasing inequality, etcetera> or it will break down. I don't see how suddenly doubling the human population would break down the system right now, much less given enough time to adapt [the bunch of years that will happen between now and whenever we hit that number]. I know you think there *ought* to be less people in the world and that we're destroying the environment and stuff, that's a common view, but we obviously can maintain the current number of people; we're as many as we are and the ecological system isn't breaking down by any stretch of the imagination.

So this

we are doomed as a species of 6 or 9 billion, although probably we will not be wiped out completely for quite a while yet. I can't believe that this idea that we can somehow decouple from the natural environment completely is anything more than a fantasy.

Given current numbers we're doomed? do we look like a doomed species? come on, bro. *doomed* ? Also no one is saying we can decouple from the 'environment'. Its just as we grow more technologically adept we can better adapt to different kinds of environments. we cannot destroy the earth, we cannot destroy the environment, that'd imply something like killing off every living thing ever. okay, we *could* do that, in theory but we're probably not gonna; humanity seems to behave more like a drunk than like a omnicidal maniac.

But again: why should anyone care? I mean, don't get me wrong, I'm all in favour of "nature". But we don't need it. If you're living in your subterranean air-conditioned city, why do you care what the weather is outside? Problems only begin once you move into a venusian hell-world. But thinking that these solar panels and the cities they support will automatically necessarily produce a venusian hell-world (and that there's nothing humanity could possibly do to stop it) is again pessimism for the sake of pessimism

This is an excellent point; turning earth into hell seems exceedingly hard. AFAIK earth's climate has been much different, from snowball to hot as fuck omnijungle, but its hard to imagine the conditions for it all to go to hell: the water and the atmosphere we cannot destroy, we can just pollute it a lot, for example, so there'll always be plants doing the basic co2+sun=o2.

He's saying that its delusional to assume our current population is stable and viable long-term. I can't help but think this is more doomsaying and ecologism [we're killing mother nature, can't you see it! and you think we should be a trillion people!?!?! this is madness!!!!!] and less a is-it-possible oriented estimation. We obviously know how to be a few billion; we *are* a few million.

[Salmoneus]

But anyway, that ignores that half of the insolation doesn't reach the surface, and that two-thirds of what does falls on the oceans (which in this model we've dedicated to our farming). On the other hand, 20% efficiency is incredibly conservative.

Surprisingly, that's not the case! About 30% of total insolation either doesn't reach the surface or is reflected away, but this is irrelevant because the Wikipedia figure is for total solar energy that reaches the surface*.

*As you said, this figure could be dead wrong, but if that's the case we can just adjust it.

My reading of wikipedia differs On the 'world energy consumption' page it says that half the insolation reaches the surface, and that this leaves 89PW. On the solar energy page, it says that 174PW reaches the upper atmosphere, of which 30% is reflected back into space. This gives an incongruity: 30% lost, or 50% lost. But it's not contradictory: 30% is reflected, it says, and "the rest is absorbed by clouds, oceans and land masses." Putting the two together, it seems reasonable to think that 174PW hits the atmosphere, of which 30% is reflected, 20% is absorbed by clouds and by the atmosphere itself, and 50% reaches the surface (89PW).
That's 780EWh per year, compared to current 140TWh consumption. Scale up average consumption to current American level, and you get ~630TWh. Divide one by the other and you get about 1240, which gives you around eight and two thirds trillion.
If we limit energy production to the land (or to an equivalent amount of the surface), you get a little under three trillion.
However, wikipedia's 'world energy consumption' page gives a different number as well, 3.8yottajoules of solar energy a year. That translates to a mere 5.9 trillion with the whole world encased, and about 2 trillion with one-third solar.
That would give us 500 billion people if we all used, on average, slightly more energy than contemporary Alaskans.

Therefore, light reflected by clouds is irrelevant. Light reflected by solar panels is relevant, but this would be included in the figures given on solar panel efficiency, so it's dealt with. Ordinary panels you buy at the store are rated at 11%, but some products I've seen online advertize 22% efficiency. Even if these are lies, it's clear that 20% is not outrageous for a future society with advanced technology.

Like I say, this is probably conservative. The current record is 43.5%, and rising rapidly. Maximum possible is apparently around 85%.
If we go with Alaskan consumption, and the 174/89PW figure, that gives us:
- 750 billion with maximally efficient PV
- 450 billion with 50% efficiency, which is probably obtainable at high prices in the near future
- 180 billion with a very conservative 20% modern technology, assuming that material shortages have badly impacted our ability to build PV, or assuming a cheaper alternative (like parabolic trough collectors) gets used instead.

And I was assuming we cover the ocean, too, but we could leave them for farming if you prefer. There is, as far as I can see, no consistent "our scenario" in this thread, though we could cooperatively make one after we're done bouncing ideas around.[/quote

True. I just meant the scenario Torco'd proposed, that I'd given a model for, and that some others had commented on.

[Drydic]

ultimately humanity will not survive. All ends, we're not gonna be the exception
but yeah, colonizing a bunch of worlds will probably increase our life expectancy

My point was more if we deliberately don't expand past this planet, we are without question going to go extinct one way or another; Sol eventually boiling the Earth us guarantees that even if we survive that long. But if we expand, beyond this solar system? We have a chance. And a chance at survival is better than the certain fate which awaits us on our fair mother planet.

Ultimately, either shall humanity go extinct, or it shall evolve beyond the point where we won't be able to call it humanity

*slaps Darkgamma around a bit with a large black monolith*

[Torco]

survive *what*, exactly. Sure, if we move beyond sol we'll survive sol... we're gonna end eventually either way. But yeah. Also, an interplanetary society would be able to sustain a much higher population; we could fuse water and replenish it by crashing bits of ice, the kind that floats around, into the ocean from time to time. Also, terraforming mars or whatever.

[brandrinn]

The heat death of the universe is inevitable.
Burn everything.

[Ars Lande]

I still think there's a lot to be said for space habitats. The resources of the solar system are considerably larger than that of any planet, and since the biosphere and industry are kept separate, you can exploit these resources to your heart's content.
Having lots of tiny, self-sufficient societies has advantages over a large integrated economy and society too: if one screws up, the other societies carry on unharmed.

In the very long term,

[Herr Dunkel]

We just need negative matter to generate infinite positive energy whilst not violating conservation

[Ars Lande]

The board ate half my post! And I can't even remember what I wanted to say.

We just need negative matter to generate infinite positive energy whilst not violating conservation

I believe infinite energy is very much frowned upon by the laws of physics. So, there's no way to escape the heat death of the universe. We're doomed, dooomed.

[Hallow XIII]

The board ate half my post! And I can't even remember what I wanted to say.

We just need negative matter to generate infinite positive energy whilst not violating conservation

I believe infinite energy is very much frowned upon by the laws of physics. So, there's no way to escape the heat death of the universe. We're doomed, dooomed.

There is. All cooling processes lose energy in the form of warmth, but if the cooling is more than the heat loss, then the net temperature approaches zero. You just need to output more cooling than the universe outputs heat! ~

[Herr Dunkel]

We just need negative matter to generate infinite positive energy whilst not violating conservation

I believe infinite energy is very much frowned upon by the laws of physics. So, there's no way to escape the heat death of the universe. We're doomed, dooomed.

You misunderstood!

Negative matter + positive matter together generate energy into infinity. It's just that you get the same amount of negative energy as you get positive energy, thus giving you a net gain of 0 Joules.
It is in violation of no single law of physics.

[Torco]

Space habitats seem like incredibly inefficient solutions to me; why build a tiny planet when there are huge ones just laying around that can make much of the work for you [incluiding energy capture, atmosphere conservation, and biosphere maintenance]. Sure they'll be very useful for stuff like scientific research, asteroid mining supervision,long-term space travel, terraformation, and all kinds of extraplanetary activities but... heck, if you wanted to *live* somewhere a space habitat seems like a horrible idea unless you're either an utopist, a hermit, or have a special predilection for the whole living in space thing: all those are small minorities.