I wanted to create an interesting scifi universe that didn't violate the laws of physics, and that means that you're limited to staying inside the solar system. I also wanted to get away from the ship-centric style of science fiction. Star Trek is ship-centric and it's all about the Enterprise - there are many other examples. What if we decided to get away from the obsession with ships and instead thought about big machines and structures that might be used to create a civilization inside the solar system?