>That means we'd be able to treat the Earth as a great big park, with little-to-no human inhabitants.
That's a nice idea, however the resources required to move enough people off the Earth just to keep the population from rising, let alone moving the bulk of the population off the planet, would be astronomical and definitely impractical.
Consider the data:
1. Population: ~7.75 billion.
2. Deaths per year: ~60 million
3. Births per year: ~140 million
4. Annual population growth: ~80 million
Let's start with the idea of keeping the population the same, rather than moving 7 billion humans off the planet.
In order to move 80 million people just into orbit, let alone have some place for them to go would require that we launch (rockets? catapults? space elevators?) about 220,000 people, along with whatever cargo is required (we'll ignore the cargo here) every. single. day.
How many rockets/space elevator cars/catapult ships or whatever would we need just to move that 80 million off the planet?
Let's use space elevators (SE) here since we can (theoretically at least) make space elevator platforms arbitrarily large.
Let's say we use an SE car that can carry 1,000 people and can travel up the elevator at 1000 km/hour.
In order to just keep the population from growing, we'd need to launch 220 SE cars a day.
Unfortunately, a round trip to/from geostationary orbit (yes, rockets/catapults could deliver payloads in much less time to low Earth orbit. But such payloads would likely be an order of magnitude less than a space elevator) at 1000 km/hour would take ~70 hours.
Which means we'd need ~650 SE cars in service at any given moment.
Loading and launching 220 SE cars a day would require enormous logistical effort:
We'd need to launch ~10 cars per hour (220 per day).
How can we load and launch 1000 people times 10 in an hour, every hour?
I suppose we could build ten space elevators, then each site could just load and launch one an hour. Which seems doable.
But where will people stay while waiting to board a car?
Just expending the resources to build (and maintain) the infrastructure for such an enterprise would be enormous. And without some serious energy (commercial fusion on a massive scale), just running these elevators would quite possibly dwarf the total power output of the planet.
And that's just to keep the population flat. Attempting to remove the bulk of Earth's population would require raw materials, manufacturing, construction and maintenance several orders of magnitude larger than the example above.
So no. We're not going to solve any population issues, let alone removing the bulk of the population, by sending folks off-world.
- cheaply access space
- cheaply access cubic miles of asteroid iron
- build whole automated production industries in space, to build however many spaceships we want
- automate the construction of spaceships and that ringwood
- use those ships and tools to automate the construction of more production facilities
You're imagining a single transport into space, but that's a mode of thinking still constrained by expensive and inefficient energy. Imagine hundreds, thousands, or tens of thousands of autonomously constructed ships all available for that population transfer.
That energy is the catalyst for an exponential growth in our ability as a species to move ourselves and control our environment. It just takes some imagination to see outside our current constraints.
It's not the ai singularity, but I think our ability to build stuff cheaply, in space, with materials obtained in the quantity they're available in space, will represent a singularity-esque leap forward.