[GeneTraylor]

>>> nice prose of your <<<

Thank you, but my prose is far from being nice. You should see my boss with a red pen around my prose. :-)

>>>but the tiny blue ball thing is bullshit<<<

Carl Sagan has another take on the matter. :-)

http://www.youtube.com/watch?v=p86BPM1GV8M

>>>Any plane on window seat will show you that the Earth is enormous and empty for most it's parts, even in China.

Don't think I advocate more cars and buildings. It's just that the tiny crowded ball argument is wrong, and dangerous, as it can be used to build a nasty antihumanism.<<<

I would argue that treating our resources as essentially endless because of the sheer size as compared to the individual fails to take into account that there are now 7 Billion people on this earth. Each and every one of them deserves a better life, they deserve to be able to have a luxurious bath, flush toilets with water, wash hands with water, eat processed foods which take a lot of water to make, wash their cars with water, drink pure water and at the end of the day consume around 315 litres of it. Of course, today not everyone lives like that except for wealthy countries (the statistic is based upon the US) but I think everyone wants a standard of life like that. If somehow, tomorrow 7 billion people started consuming water like that then we would drink up 2 205 000 000 000 litres of fresh water in a day, but the total possible water supply we can access (and this includes the glaciers) is only 3.5 × 10^19 litres...

That's quite an easy way to run out of water.

Now if you do the same with energy, with waste, with consumption and so on what you have is a ticking time bomb waiting to explode. The way we live today just can't last. I think that you can solve this problem using technology, but its roots lie deep in our societies.

What's frightening over here is that there is no way out for us. Unlike our ancestors we simply can't burn and move on. The earth is where we have to make our stand. I really think that it's important for people to start taking the gravity of the situation seriously. We need solutions, and we need them fast. Our time is running out.

I think that there is no greater form of humanism than realizing that all of these people need to be saved from such an horrible end and devoting your entire life to creating a better future.

[randallsquared]

we would drink up 2 205 000 000 000 litres of fresh water in a day, but the total possible water supply we can access (and this includes the glaciers) is only 3.5 × 10^19 litres...

That's quite an easy way to run out of water.

Water doesn't vanish after it's used. Also, putting your first number in scientific notation helps put this in perspective: 2.2 x 10^12 . Seven orders of magnitude. Close to 15 000 0000 times as much.

That's not to say that work isn't needed to develop cheap recycling appliances, and to build water systems that recycle and reuse waste water rather than dumping it all into the environment, but it's not a very hard problem on the scale of things humanity can accomplish -- it mostly just requires more energy.

Energy will continue to be the limiting factor for a long time, and eventually (after essentially perfect recycling of all material civilization requires) the limit will be waste heat. But as others have mentioned, we have a whole solar system to use as well, and moving the highest heat processes to space would allow us to radiate it away without affecting the earth. Technology which is clearly within our reach would allow the earth to support trillions of humans -- admittedly at a more crowded level than I would prefer. :)

[GeneTraylor]

>>> Also, putting your first number in scientific notation helps put this in perspective: 2.2 x 10^12 . Seven orders of magnitude. Close to 15 000 0000 times as much. <<<

Hm, I made a big mistake in that comment. I should have added that we have access to this much, but the real catch is energy and how we are currently limited to tapping into it and the total resource we can access is X.

Thank you so much for pointing this out.

>>> it mostly just requires more energy <<<

Yeah as I argued in another comment, that really is the unmentioned catch over here. I should have elaborated upon that in the parent. Sorry.

Even if most of humanity doesn't reach that level of consumption, we will need to start unlocking some of this resource sooner or later. What really worries me is the amount of energy we need to unlock all of this water locked away in glaciers, ice caps and so on and then actually manage to process and distribute it for final use.

That's a really interesting but hard engineering problem.

>>> Technology which is clearly within our reach would allow the earth to support trillions of humans -- admittedly at a more crowded level than I would prefer. :) <<<

Can you please elaborate more?

[Turing_Machine]

<I>The earth is where we have to make our stand</i>

Why? We have a whole solar system right on on our front porch.

<I>but the total possible water supply we can access (and this includes the glaciers)</I>

Water doesn't just get used once and then disappear forever. Now, one could certainly make an argument against (say) sucking water out of the Oglalla Aquifer faster than it gets replenished, but that's a localized problem. We aren't going to "run out of water". Really.

[GeneTraylor]

>>> Why? We have a whole solar system right on on our front porch <<<

This is an honest question, not a rebuttal. How would you get those resources here, or us over there?

>>> Water doesn't just get used once and then disappear forever. Now, one could certainly make an argument against (say) sucking water out of the Oglalla Aquifer faster than it gets replenished, but that's a localized problem. We aren't going to "run out of water". Really. <<<

Well it would have been labored to add that although it would take a large amount of energy to purify water, or perhaps desalinate our oceans, the loop can be closed. The problem really is that it takes resources to keep that loop closed.

I think that all of our issues today boil down to how we convert energy to extract work, if we do manage to make something like fusion work then all of these concerns could be undermined with technology, but how do we get from here to there?

[randallsquared]

How would you get those resources here, or us over there?

There are a number of high-startup-cost, low-running-cost schemes for putting stuff in LEO, and as someone once said, LEO is halfway to anywhere in the solar system, energy-wise. Some possibilities are laser launching, space elevators, launch loops, and electromagnetic guns.

Some of these have much higher startup costs (to be effective for human launching, a gun would have to be very, very long and possibly cost the most of any of these, but shorter ones could launch material at very high acceleration with much less up-front cost), and some of them have awful failure modes (the space elevator could spread destruction in a narrow path wrapped all the way around the earth if it failed in the wrong way, via separation from the counterweight), but they're feasible.

The cheapest ways of getting to orbit, therefore, approach the cost in electricity of the task, which is less than 10 KwH per kilogram, or about $2USD per kilo. A recent flight from coast to coast cost more than that for me.

[GeneTraylor]

I've actually thought about this a bit, and I think that a really interesting design for a launch gun would be to encase the payload in a cover composed of diamagnetic material and then pump liquid nitrogen through channels made inside the material. The material would become perfectly diamagnetic and it will repel all fields, so you can easily levitate it and use it's tendency to go from a stronger to a weaker field to accelerate it.

I don't know for sure, but I think that the main advantage of doing something like this versus just putting a magnet over there, would be the fact that an accelerating magnet in such an assembly would generate huge amounts of back-emf and you would have to a) sink that and b) compensate for that.

However I don't know much about what other people's designs are, but I would like to change that. Do you know any resource where I can learn more from the scratch on how to build something like this?

Also where can I read more in detail about launch loops, laser launching, and space elevators?

[randallsquared]

I haven't paid much attention to these areas in a while, but I would start here: http://en.wikipedia.org/wiki/Non-rocket_spacelaunch

[gbog]

I see a demographic problem if and only if Americans continue spreading their unhealthy way of life.

[mooism2]

It's not about Americans spreading their unhealthy way of life. It's about non-Americans claiming that life (more or less) as their own.

[gbog]

Well, you know, I live in Chine since 8 years and, in some ways, there is a profound influence of the "American way of life", mostly through the channel of Holywood movies. The matter could be worse: Chinese have the weight on their side, they can't change so fast as to lose their identity, but still, they have an idea of what should be an happy life that is formatted by these f* movies (really hate then, sorry). For instance, they think everyone should ought to live in an appartement in a tower, own a car, drink canned soda, eat industrial food cooked in microwave, have only one overprotected child, work in suits, go shopping each Saturday, watch baseball on a gigantic TV on Sundays, etc.

They can't believe it when I tell them I am living in a cheap courtyard house, rides a bike to work, never drinks soda, eat home cooked food, never watches TV, know nothing about baseball, climbs mountains on the week-end. In fact, it is the way their parent and grand-parents lives (eg. my neighbors) and the younger generation don't want that, they want the "American way", the supposed "comfort". Maybe a personal taste, but I think Chinese way is better, for me, my family and even for the little big blue ball floating in the universe.

Don't get me wrong: I know US citizen do not live like described, and I tell my friends and colleagues as much as I can. But the problematic part is, again, those f* Hollywood movies that have too much worldwide influence. (I therefore welcome any other influence, Mangas, Bollywood, Hong-Kong kungfu, anything else is better.)

[slevcom]

I smell a troll.

[gbog]

Ok, it may be "trollish" to say that the American way of life is unhealthy and bad for the environment and to express disapproval when this country spread its bad habits around the world. It is true nonetheless.

(Or maybe you think it is OK to eat 1kg of meat/day, own 1 car/person, drive 2h/day, eat burgers and watch TV?)

So facing this issue, two solutions:

1- Human being should be able to consume more, and therefore there need to be less of them.

2- Human being do not need to consume that much to be happy and, therefore, their demographics is not that much of an issue.

I let you choose.