Gravity control unit
From Tardis Wiki, the free Doctor Who reference
The Laima of Trion installed a gravity control unit into Earth to prevent the gravity constant from getting in the way of their plan to move into the next universe. The influenced every measurement of spacetime on the planet, meaning that humans there were incapable of discovering the correct nature of the speed of light. (PROSE: Turlough and the Earthlink Dilemma)
