Isaac's Universe is a fictional universe created by Isaac Asimov for other science fiction writers to use as a setting. It introduces the collaborative science fiction universe created by Asimov which eventually resulted in five volumes: three short story collections and two novels. It was initiated by Martin H. Greenberg, who also edited and published its three short stories collection by Avon Books starting in 1990.Volume One: The Diplomacy Guild is 258 pages long, not counting an additional couple of pages in back on the authors contributing their works. There is also an introduction by Asimov that is seven pages long. This was followed by Volume Two: Phases in Chaos and Volume Three: Unnatural Diplomacy. The novels are: Fossil by Hal Clement and Murder at the Galactic Writers' Society by Janet Asimov.The premise of Isaac's Universe is that the Milky Way Galaxy in the future is populated by six high-tech, space-faring species, a response by Asimov "to criticisms that he had rarely dealt with aliens": Erthumoi: Human beings, who have colonized many planets beyond Earth and have extended their lifespans with rejuvenation treatments. Cephallonians: An aquatic species who live in water-filled spaceships, described by Asimov as vaguely analogous to porpoises. Locrians: A skeletal, insect-like species, adapted to a low-oxygen atmosphere with neon rather than nitrogen. Naxians: Limbless, snake-like beings, able to read the emotional state of individuals from any organic species just by observing them. Crotonites: A small winged species who live in an atmosphere poisonous to the other species, and who consider the other species inferior and look on them with contempt. Samians: Physically powerful, slow-moving, block-like creatures with no appendages who live on a high gravity planet.Robert Silverberg, who wrote the first Isaac's Universe story, added the idea that there is a seventh, mysterious race which has never been seen, but which has left behind artifacts spread throughout the galaxy. Source: Wikipedia (en)