[0x12]

Whatever the limit is, there is a limit. Because there is a limit to the earth. Whether that limit of sustainability is 2 or 50 billion is something we haven't figured out yet but that there is a limit seems to be something you can't around.

[ars]

Why is the limit on earth?

[0x12]

Because it just so happens that this is where we are.

Earth can only sustain so many people, and since we do not currently have a viable way to get off this earth and/or to terraform other planets (hell, we can't even agree on a common plug to use for household appliances) it looks like it will remain that way for a while.

[ars]

Yah, but it will also take a while to reach the limit of the earth, by that point we will hopefully be able to expand off of the earth.

[jeffreymcmanus]

Um, we've left the earth already. The only reason why we don't continue to do so is that it isn't cost-effective -- which means that we have another resource-allocation problem rather than some mysterious insurmountable challenge.