The Limits to Growth "fallacy"

--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:
--- In spacesettlers@yahoogroups.com, "William" wrote:
>> Long before the structure you describe gets built it will have
>> collapsed under its own weight. It's estimated that even buildings
>> made out of pure diamond can only go up about 600 km., and even
>> that's not taking into account earthquakes and continental drift.
>
> I don't know what advanced materials might be available

So you hand-waved it in. The only thing stronger than pure diamond is
osmium: only slightly stronger, and really rare. Diamond is made out
of carbon which has the strongest chemical bonds in existence, the s2
and s3 bonds. They've been able to make carbon nanotubes with about
twice the compressive strength of diamond, but these nanotubes have no
lateral strength which makes them useless as building materials.
I doubt those materials will be *that* much stronger than diamond.

> but I do know it would be absurd to build the top out of the same
> material as the base.

Diamond also has a very high strength-to-mass ratio. Not absurd.

>> Which would require importing many times the amount of nitrogen as
>> there is on Earth
>
> Yes. And?

The original argument was over the carrying capacity of the entire
Solar System, versus "just the Earth".

There's some gray area about the meaning of *just the*, and how far
that extends from the top of the atmosphere. Past LEO orbit? GEO
orbit? Cis-Lunar space? Earth's gravity well?

>> Your original point was "there's far more resources on Earth than
>> the rest of the Solar System". Q.E.D.: Not So.
>
> That's not an accurate quote of me. Do you mean this?: "There are
> (non-hydrogen) resources near Jupiter, but they're badly outclassed
> by the resources of Earth."

Original statement:
"the solar system as a whole can support many orders of magnitude
more than just the Earth"

Your response:
"Maybe not, given that Earth accounts for almost half the free rocky
mass in the solar system"

> Most people are not looking for more nitrogen. I don't think, over
> the next 500 years, anyone is going to be looking for nitrogen. The
> first non-Earth place I would look for nitrogen, though, might be
> Venus. Mining Venus for nitrogen hardly qualifies as "[settling]
> most of the system in large numbers".

In your scenario of 1e18 people each with 1e6 foot3 space/air per
person with enough space, to avoid having a human-beehive on the
Earth, would require importing about 2000 times the nitrogen than is
on the Earth. From...where? Oh, that's right: elsewhere in the Solar
System.

Venus has only 3.5 times as much nitrogen in its atmosphere as in the
atmosphere of Earth, and could hardly even make a scratch in this
requirement.

You would have to scour the entire Kuiper Belt, plus part of the Oort
Cloud. Or maybe break up the gas giant planets. A *huge* use of the
resources in the entire Solar System.

> Again, placing a sunshade at Sun-Earth L1 hardly qualifies as
> "[settling] most of the system in large numbers".
>
> If generating power *while* shading the earth from the sun offends
> you, then the necessary power could simply be generated with fission
> of heavy-metal fuel sent from Earth.

Which would mean using another resource that would not be sufficient
on Earth -- the radiating area out in space, and its ability to
dispose of waste heat.

> You're not seriously proposing that Earth-based civilization needs
> more energy resources, are you? There are 40 trillion tonnes -- 32.4
> billion years' worth at the present burn global society all-fuels
> burn-rate of 16 terawatts -- of fission fuel (40 tt uranium + 160 tt
> thorium) in the earth's crust alone.

According to my calculations with a quintillion (1e18) people you say
the Earth can support and just 200 watts/person, that material would
last for 2519.2 years. After that humanity would have to either leave
Earth or suffer a massive die-off of some 99.9 percent of its
population.

About the only thing left would be the possibility of using the more
plentiful elements in the Earth's crust (oxygen, silicon, etc.) for
fusion power. Maybe.

Earth alone cannot support anywhere near a quintillion people. Not
without having a megastructure around it; a gigantic dyson swarm of
both energy-supply and cooling lasers, stretching all the way to the
moon or beyond, and then deciding to call that "just the".

It's carrying capacity somewhere around the solar insolation energy
(1.74e17 watts) divided by whatever power consumption per person is
used. Even with some sort of hyper-efficient, human-beehive scenario
of just 200 watts per person, this is 870 trillion people. At the
current U.S. value of 10 kw/person, that goes down to 17.4 trillion
people.

Even these would involve building megastructures here on the Earth to
house all those people. Could those megastructures last on the Earth,
with its earthquakes, volcanos, rising/sinking land areas and
continental drift? The tiny-by-comparison Three Gorges Dam in China
right now has already caused earthquakes.

And then there is the Solar System which can support *at least* a
quintillion people, in style.