Nebusj said:
Folks may feel that, but planets are really, really big things. A 50 billion-person Earth, without adding any sub-oceanic development (which is obviously credible for the Trek universe) would be about as densely populated as Belgium is today, and most people seem to find that pretty livable. Given that there'd be a considerably reduced need for high-volume, low-value activities like agriculture or technologies like reservoirs and aqueducts or the like, you could see an extremely high-population planet with actually enormous stretches of apparently unused land.
A 100-billion-person Earth doesn't quite reach the population density of the (English) Channel Islands, and a trillion-person Earth gets to around the densities of Singapore or Hong Kong, although those are such small areas it's hard to say what the perceived population density (how many people per square kilometer people see on average, and a much less obvious calculation) would be for the whole world.
