Define "crowded" (how many people per acre does a typical spaceship hold? How about the earth?). Define "limited" (the spaceship analogy heavily implies it's be

Define "crowded" (how many people per acre does a typical spaceship hold? How about the earth?). Define "limited" (the spaceship analogy heavily implies it's being used in a sense other than "not infinite"). Go find out what this "renewable" stuff people keep talking about these days is.