I fell for hours.

This is not hyperbole. I was not in space. Not technically.

Imagine a giant sphere as thick as a planet surrounding a star with a radius that puts its inner surface at a habitable distance. Pour enough air into it to give the inner surface a decent atmosphere, and you have enough habitation space for the population of a whole galaxy. This is a Dyson sphere.

Now imagine an army of robotic construction vehicles launched to build these in advance for settlers from an overpopulated empire of Dyson spheres. Imagine these construction vehicles hunting down black holes and ripping them apart for building materials.

Now imagine this gets out of hand. That shouldn’t be a stretch.

Eventually, the whole damn galaxy is covered in giant metal scaffolding and junk. A contiguous, semirigid structure, most of it filled with air and an infinite variety of life.

In such a place, you’re bound to find doors without warning labels in your language.

“Caution, open transit shaft!” would have been so nice.