Editing Known Space (section)

===Invulnerable hulls===
The [[Pierson's Puppeteer|Puppeteer]] firm, [[General Products]], produces a series of invulnerable starship hulls, known simply as the [[General Products#General Products hull|General Products hull]]. The hulls are impervious to any type of matter or energy, with the exception of [[antimatter]] (which destroys the hull, as demonstrated in "Flatlander"), [[gravitation]] (demonstrated in "Neutron Star"), and visible light (which passes through the hull). While invulnerable themselves, this is no guarantee that the contents are likewise protected. For example, though a high speed impact with the surface of a planet or star may cause no harm to the hull, the occupants will be crushed if they are not protected by additional measures such as a stasis field (''Ringworld'') or a gravity compensating field.

In ''[[Fleet of Worlds]]'', the characters tour a [[Pierson's Puppeteer#General Products|General Products]] factory and receive clues that allow them to destroy a General Products hull from the inside using only a high-powered interstellar communications laser. In ''[[Juggler of Worlds]]'', the Puppeteers, attempting to surmise how this was done without antimatter, identify another technique which can be used to destroy the otherwise invulnerable hulls, one which does suggest some potential defense options.

The strength of the hulls was revealed to be based on the fact that they were essentially one giant molecule.