And other than public domain science fiction, how can I track down Creative Commons science fiction that is safe for re-mixing, i.e. fan fic?
I created a universe a while back called Time Bridge. This was before CC existed or was at least popular. It was a world building effort centered around a few periods of time all focused on a big time machine in space. The machine functioned on crap science, however everything else in the world was meant to be Hard SF.
I don't know if any of it still exists. It wasn't very popular and aside from a few role-players and artists, I was the only person working on it. Still, remnants should be out there still, maybe via the wayback machine. Who knows.
I can try to dig it up and re-post it somewhere if anyone wants. Say if I get 20 upvotes on a comment I add to this answer.
The Dryden Experiment is an entirely Creative Commons 3.0 driven universe.
The universe I created in Blaze Master Mysterium of the Universe is safe for use in your fanfictions, if you like my stories feel free to use the world and settings, I am a little attached to the main character though, but feel free to use the rest, just credit me on the ideas you use.