I've a transhumanist streak, I prefer to exist by the motto 'Live for ever or die trying'




More worlds is overrated, with fusion stars and planet become so much useless detritus to be harvested for material. You could literally fill a single solar system with more habitable land than any galaxy would naturally have. Think of a planet as like a cave in a mountain-island in the ocean. Naturally it's a very handy home, maybe even a few medium-sized apartments worth of space, but if you rip down that mountain and use it as construction material you can change what was maybe a few thousand square feet of living area into an artificial island containing a few billion square feet of living area, without even going multiple storeys. One mountain would have nearly a trillion tons of building material and you'd be able to increase your living area a billion fold over that cave. You could construct, with modern tech, a nice little O'neill cylinder pair with about 1000 square miles of land, the size of a large county, as it's own happy little suburb or forest preserve, with a mass budget of about 50-100 billion tons of material, and from something like Mars you could about 5-10 billion of them, 5-10 trillion square miles of land versus Earth's 50 million square miles of land. 100,000 times the living area from 10% of the mass. It might be interesting to terraform a planet and have to put up with it's non-Earth day, non-earth year, non-Earth gravity, and have to do all sorts of decidedly non-natural stuff like domes or orbital mirrors to make it livable, but I for one would rather have the option picking from several billion worlds each gardened or left to wilderness or tuned to some bizarre grav or pressure of our choice then one single world with room for a microscopic percentage of the people.

And if you've actually got fusion those little worlds don't have to huddle around the sun, you could spread them out over light years in their trillions and still be able to get to your neighbors in hours or days or weeks. You'd not need to find those planets which might be good for life... and which might left to themselves develop life... you could go find random brown dwarfs in the void or rogue gas giants, build dozens or thousand of those things from whatever rings or garbage is floating around them, and tap them for hydrogen sufficient to run those island worlds for trillions of years. I mean other star systems might seem nice, but really wouldn't it be the option of seeing trillions of little city states each going their own route that would be coolest? Ones that could be visited without FTL in a normal timespan at that? They don't have to be Earth-like, they could be everything from space equivalents of gas stations housing a few dozen people to giant low gravity bubbles where jungles the continents of Earth sprawl pristine over the landscapes and creatures so large they could never live let alone fly on Earth dot the sky.

Not that I wouldn't love some FTL ability, but that just doesn't seem on the table and I just want to emphasize, we don't actually need it to have worlds in their millions ranging from human normal to utterly alien mere days of travel away.