Backstory for a Sci-Fi Novel/Film

by TheBloomingIdiot

The future. It has been decades since the human race solved its waste problem by transporting sewage, garbage, etc to a parallel universe (or another dimension). The authorities always claimed that this universe/dimension was far larger than our own and completely empty. In fact, this other universe/dimension is densely populated by beings we can only dimly understand — beings who have finally figured out how to strike back.