system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar] Did Earth colonize other star systems in the immediate area besides Centauri?

How far did the human race extend and/or explore by the time Avatar takes place? Was the Centauri system where it takes place the only other star system that we reached to that point?
gpt
The documentary and its associated materials don't provide a conclusive answer. What we do know is that there are 20 billion people on Earth, which has been ecologically ruined to the point that there are no big cats outside captivity (the Bengal tiger recently having been resurrected through cloning), and half of today's fish species are extinct along with all whales. 

There are small human and automated outposts throughout the Sol system, providing minerals and other raw materials - but not nearly enough to keep up with human demands, let alone restore a functioning ecology. 

So why launch an interplanetary expedition in the first place? RDA evolved out of the early asteroid mining startups of the 21st century. Its institutional DNA came out of that period of reckless optimism. Even so, RDA's first 5-kilometer starship prototype consumed years of profits. Influential world leaders pressured the Interplanetary Commerce Administration to grant RDA's most important condition: that it be granted monopoly rights to any resources discovered in the Alpha Centauri trinary system. This gamble paid off beyond anyone's wildest dreams when Polyphemus was found to harbor life - *intelligent, charismatic* life - as well as unobtainium. 

Unobtainium mining is controversial, but its impact on Earth cannot be understated. It made possible the construction of world-spanning maglev lines, each train capable of hauling thousands of tons of cargo at a minimal cost. Those lines double as power transmission conduits. Without unobtainium, fossil fuel use would begin to rise again, and the cost of transmitting energy from large fusion reactors would no longer be competitive with a network of coal- or gas-fired plants. 

Without unobtainium, we lose all the progress we've made. To keep 20 billion people alive in a ruined world takes constant effort and vigilance. Most of us have grown up on nothing but bars of vat-grown algae and bug powder. We've got greenhouse emissions down. We've relocated people from the ruined coasts. We've cleaned up a lot of the old messes and we're working hard to re-establish viable ecologies. We've adapted. Many of us have even managed to thrive. But without unobtainium, we lose all that. We start the downward cycle all over again. 

Unobtainium is the last hope for Earth. It's the last hope for humanity.

That is why RDA's shareholders have never approved an expedition to another system. Every ship pissing about in the unknown is one not hauling back unobtainium. 

As for the Na'vi? Terrible loss if they all died. But not as terrible as all of us dying.