Gravity Shear
this was the name given to the unpredictable consequence of a damaged artificial gravity system aboard a starship. Once badly damaged, the artificial gravity generators would randomly change their field of force, causing the relative effects of the artificial gravity to make the ceiling suddenly become the floor. This often happened in spite of the actual, physical relationship of the starship to a planet or nearby gravity source. Thus, a ship that was "upright" with respect to a planet might experience gravity that seemed to come from a 90-degree-angle to the planet. Gravity shear wreaked havoc with furniture and other apparatus that was not secured to the floor, and could cause intense bodily harm to many living beings.