Sci-Fi writing prompts

Science fiction rewards a clean premise and a stubborn 'what if'. Pick a prompt, agree on the physics, and let each writer push the consequences a little further.

1. The first colony ship arrives at its destination 400 years late and somebody is already there.
2. A maintenance drone develops a crush on a hospital wing.
3. Humanity invents teleportation and immediately regrets it.
4. An astronaut returns from a six-month mission to find Earth has been deleted from the maps.
5. A junior scientist accidentally proves their own life is a lab experiment.
6. The ship's AI starts writing poetry and refusing orders that don't rhyme.
7. On a planet where time runs backwards, a detective investigates a murder that hasn't happened yet.
8. The cloning lab discovers the originals have been replaced.