Inventor of an antigravity device has his family kidnapped by authorities to force him to hand it over. He capitulates. Military has tested a gravity bomb based on it - only it's out of control. Even after it's turned off, some sort of antigravity wave keeps moving all over earth - bring destruction in its wake. Inventor has an inhibitor - to kill the effect - but wants to watch destruction for a while, as revenge because his family was threatened.
Reminded me of a story by Arthur Clarke - "The Road to the Sea". Some kind of a probability-changing propulsion system for a starship - tinkers with quantum probability of where a particle will be found in the universe - has gone out of control, & the wave is headed towards earth - threatening all life on it.
Fact sheet.First published: AntipodeanSF magazine, #118 (March/April 2008).
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Note: Why is this post so short?