| Only so many items can be recycled, so we lose the material of those that can't, which is what I mean by 'work to a point'. Sooner or later, definately later than sooner, we will lack raw material. Perhaps material can be synthesized, but it would have to be synthesized from something.
If the population growth continues as it is, and since more population will produce even more population, compounding it, it will only increase. Again, sooner or later, definately later than sooner, space will be literally unavailable unless we start building vertically and digging into the ground. We can only dig so far, and only build so high, however, so space is still finite.
Now, I'm talking like thousands of years into the future, not the next hundred. This is also assuming a nuclear war or asteroid crashing into the Earth doesn't destroy all life, either.
As for space travel being profitable, yes, in the long run. But it takes cost to get there. Take the colonization of America, a very costly endeavour to undertake at first, but it quickly paid for itself. Trade and raw material helped the European powers prosper that funded the expeditions. In space, it is reasonable to assume the same thing will happen. That Economic Viability of the Colonization of Mars paper is an interesting read, so if you have the time, I recommended anybody interested in the subject read it. |