An eternity later, the universe having turned out to have positive curvature and lots of mass, the boomerang hits him in the back of the head.

"Further Boomerang Difficulties", by Randall Munroe, licensed under Creative Commons Attribution-NonCommercial 2.5 License

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An eternity later, the universe having turned out to have positive curvature and lots of mass, the boomerang hits him in the back of the head.