Creative writing assignment notes. Try free writing. Brain storming. Assignment due next week. Idea for a new story?
Alternate universe. Maybe trite, but why not? I like it. Dystopia? People seem to like that stuff for some reason.
Reductio ad absurdum. How bad could "bad" possibly be?
Tweak physical laws, change something from our universe, just one thing. How about "c"? Velocity limited to the speed of light? Interstellar travel as we know it would be impossible!
Effects? Without interstellar travel, limited to near earth orbit only. Ew. Boring. OTOH, everyone is stuck on earth and has to learn to get along -- or die trying. Food shortages? Fresh water? Population controls? An earthbound arms race with doomsday weapons? Could I make that believable?
Tweak. Take away carbon nanofilaments. No space elevator. Even low earth orbit becomes impossibly expensive again.
Tweak. Take away fusion. Bring in energy scarcity. What would that be like? Geopolitical instability. Wars fought over old-school energy resources. Pollution?
OK, just a setting. Plot? What's the conflict? Seems like almost everything would be a conflict. Energy scarcity might like a good place to start. Burning fuel to release heat. Thermodynamic limits. Primitive. Almost Stone Age.
Something crazy, some guy trying to perfect a fusion reactor and solve the energy shortage? But he's laughed at, scorned?
Can't get funding?
Maybe it's too ridiculous.
Life on that earth? Maybe too awful for this project? Not sure I can really do justice to that much dysfunction!
Perspective. Every world is someone's dystopia.