| Isaac Asimov, The End of Eternity | The classic story about a culture meddling with the timestream, and political complications thereof. |
**
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| Stephen Baxter, The Timeships | Brilliant sequel to H.G. Wells The Time Machine that deals with the effects of how time travel changes history and the cosmic consequences. Highly recommended. |
***
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| Greg Bear, Eternity | Sequel to Eon. Major space-time engineering, advanced cultures mining other cultures for information and ultra-advanced civilizations with their own designs on the universe. Plenty of ideas for Ex cultures. |
*
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| Greg Egan, Diaspora | A good description of posthuman societies and their exploration of the greater universe. Good mental training for dealing with time travel and the beings of Ex Tempore. |
*
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| Ken MacLeod, Cosmonaut Keep | Humans dealing with far older non-human cultures – and human cultures separated by centuries. |
*
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| Dennis Lindblom, Allt Har Sin Tid | Story about some early time travelers and how they struggle to get home to their original timeline. |
***
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| Dennis Lindblom, Frostens Barn | A good description of how an isolated community of humans develops faster and faster, essentially undergoing a singularity and becoming posthuman. |
**
|
| Olaf Stapledon, Star Maker | Grandiose novel about the evolution of life in the universe. Especially notable is the last part, where the Starmaker experiments with different universes – this is the kind of things some of the mainliners like to do. |
*
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| Vernor Vinge, A Fire Upon the Deep | Space opera in a world where both primitive, advanced and postintelligent civilizations coexist. |
**
|