Science — It is notable that in Known Space, as in other science fiction universes, artificial gravity appears to operate within sharply bounded areas or volumes. For example, when the Lying Bastard crashed on the Ringworld floor, there was a sharp boundary between the ship's cabin gravity and the exterior, Ringworld gravity: "Louis entered the lock... He remembered the tilt of the ship in time to grab at the jamb as the airlock opened. As the cabin gravity went off Louis swung around, hung by his hands for an instant, and dropped" (Ringworld ch. 10, p. 134). Normal gravity radiates out in all directions from a mass; gravitational force only drops off slowly with distance (except with black holes and neutronium). How can it be that artificial gravity works so differently?
Fanfix: Note that according to Relativity theory, gravity is only a side-effect of space being "curved" by a mass. If it were possible to somehow artificially curve space, without a large mass being present, this might have the effect described. We postulate that there are "positive" and "negative" artificial gravity emitters; tension between the two emitters curves space. Normally, for providing positive gravity, the positive emitter would be in the floor and the negative emitter in the ceiling. Reversing the polarity for negative gravity could be used to counteract a heavy gravity field; for instance, In the Camelot Hotel on Jinx, the gravity in each room can be individually set to a lighter gravity than is the norm for Jinx. Note that spaceships, to fully compensate for acceleration in any direction, would have three sets of emitters, one for each axis of direction: up/down, right/left, forward/back.