be unable to generate thermoelectricity. Outsider 'ships' are equipped with an artificial 'sun' for their journeys between systems, but because of the nature of their 'ships' the hyperspace 'blind spot' would absorb this artificial light, killing Outsiders who remained in hyperspace too long. (The canonicity of this material is debatable as it was not written by Niven.) The novel A Darker Geometry by Gregory Benford and Mark O. Martin revealed that the Outsiders were created by a race of extra-dimensional aliens seeking to escape the heat death of their own universe. Edward M. Lerner revealed in an online chat (as 'EML') that Larry Niven had ruled A Darker Geometry as definitely non-canonical and incompatible with the then forthcoming Juggler of Worlds, which was co-authored by Niven and Lerner. Juggler of Worlds introduces a number of possible retcons to established Outsider history. While in most of the Known Space Series, the name "Outsiders" refers to the aforementioned species, in stories that happen before the discovery of aliens the term "Outsider" refers to any alien that might make contact with mankind. The Outsiders may have inspired the Melnorme, from Star Control 2, another highly advanced and very mysterious species. The Investor species in Shaper/Mechanist stories by Bruce Sterling have a similar ethos but an altogether different biology. Pak Protectors Pierin The Pierin are a rare multi-limbed species which developed on a planet with lower gravity than Earth, thus Pierin spend much time in the air. They have horns on their heads and wide membranous wings. They speak in raspy screeches and atonal clicks. Pierin are described as curious and friendly to the point of being nosy. They were able to develop a small space-faring civilization before being enslaved by the Kzin. Their planet of origin is known as Pierin, orbiting a star in the constellation Reticulum. At some point Human beings tried to ally with them against the Kzin. They eventually were liberated from slavery during the Man-Kzin wars. Pierson's Puppeteers Thrintun The Thrintun (singular Thrint; also, Slavers) are an ancient species that ruled a large empire, including the region of Known Space, through telepathic mind control about 1.5 billion years ago. A technology created by one of their slave races was the stasis field, which makes its contents impervious to harm and provides indefinite suspended animation, and which has figured in several Known Space stories. Thrintun were small (approximately 1.25 meters