Item from enders-game by Orson Scott Card
The Little Doctor — a weapon that creates a field where electrons can't be shared, spreading spherically through all matter it contacts. Ender used it to destroy a planet. Someone almost used it again on Lusitania.
The MD Device (nicknamed 'Little Doctor' from the acronym) is the Enderverse's weapon of mass destruction. Its field causes electrons to stop being shared between atoms, and this effect spreads spherically — weakening with distance but strengthening on contact with more matter. Fire it at a ship, and the ship disintegrates. Fire it at a fleet clustered around a planet, and the field propagates through everything. Ender deployed it against the Formic homeworld in his 'final exam.' He chose to target the planet rather than the fleet because the fleet was too large to defeat conventionally. He didn't know it was real. An entire species died in the expanding field. Millennia later, Starways Congress loaded another MD Device onto a fleet sent to destroy Lusitania. Jane redirected the weapon back into its own ship. The universe's most terrible weapon exists because humans are very good at building things that make other things stop existing.
A beam weapon mounted on starships. Two beams converge to create the disruption field. Visually, it turns matter into expanding clouds of ionized particles. The aftermath is nothing — no wreckage, no debris, just absence where a planet used to be.
Also known as: MD Device, Little Doctor, Molecular Disruption Device