The Fermi paradox is the conflict between the lack of clear, obvious evidence for extraterrestrial life and various high estimates for their existence. As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now."
A sleeper ship is a hypothetical type of crewed spacecraft in which most or all of the crew spend the journey in some form of hibernation or suspended animation. The only known technology that allows long-term suspended animation of humans is the freezing of early-stage human embryos through embryo cryopreservation, which is behind the concept of embryo space colonization.
The idea of self-replicating spacecraft has been applied—in theory—to several distinct "tasks". The particular variant of this idea, applied to the idea of space exploration, is known as a von Neumann probe, after the mathematician John von Neumann, who originally conceived of it. Other variants include the Berserker and an automated terraforming seeder ship.
The Uplift Universe is a fictional universe created by American science fiction writer David Brin. A central feature in this universe is the process of biological uplift.
The Saga of Seven Suns is a series of seven space opera novels by American writer Kevin J. Anderson, published between 2002 and 2008. The books are set in a not-too-distant future where humans have colonized a number of other planets across the galaxy, thanks in part to technological assistance from an ancient alien race, the Ildirans. The series chronicles the universe-spanning war that erupts when humans inadvertently ignite the fury of a hidden empire of elemental aliens known as the hydrogues. Internal conflict is sparked within both the human and Ildiran empires as other ancient elemental races reappear to renew their own ancient war with the hydrogues.
The Commonwealth Saga is a series of science fiction novels by British science fiction writer Peter F. Hamilton. This saga consists of the novels Pandora's Star (2004) and Judas Unchained (2005). Hamilton has also written several books set in the same literary universe. Misspent Youth (2002) takes place 340 years before the events of Pandora's Star. The Void Trilogy, consisting of The Dreaming Void (2008), The Temporal Void (2009), and The Evolutionary Void (2010), takes place 1,200 years after the events of Judas Unchained; several of the main characters from Judas Unchained and Pandora's Star also appear in the Void trilogy.
Cluster is a series of science fiction novels by Piers Anthony. Anthony originally conceived of and wrote the series as a trilogy but later added two additional volumes.
The Alliance–Union universe is a fictional universe created by American writer C. J. Cherryh. It is the setting for a future history series extending from the 21st century into the far future.
The fictional portrayal of the Solar System has often included planets, moons, and other celestial objects which do not actually exist in reality. Some of these objects were, at one time, seriously considered as hypothetical planets which were either thought to have been observed, or were hypothesized to be orbiting the Sun in order to explain certain celestial phenomena. Often such objects continued to be used in literature long after the hypotheses upon which they were based had been abandoned.
The planetary systems of stars other than the Sun and the Solar System are a staple element in many works of the science fiction genre.
Star Guard is a science fiction novel by American writer Andre Norton, published in 1955 by Harcourt, Brace & Company. It is an example of military science fiction, based on European ancient history.
X is a science fiction space trading and combat simulator series created by German developer Egosoft. The series is set in the X-Universe where several races populate a number of worlds connected by jumpgates. The games feature free roaming gameplay with trading, combat, empire building, and missions; leading to the series' phrase: "Trade, Fight, Build, Think". The series, which was launched in 1999 on the Windows platform, consists of five base games: X: Beyond the Frontier, X2: The Threat, X3: Reunion, X Rebirth, and X4: Foundations. X Rebirth introduced a new rendering engine as well as a new plot, one which X4: Foundations now extends the storyline beyond ten years after the events in X Rebirth.
Probability Moon is a 2000 science fiction novel by the American writer Nancy Kress.
William Greenleaf is an American author. He was born in Illinois, spent most of his life in Southern Arizona, and now lives in New Mexico near Santa Fe. He is a graduate of Arizona State University and worked as a corporate strategic and financial planner before changing careers to become a novelist, freelance book editor, and creative writing instructor.
The Inheritance Trilogy is a series of military science fiction books written by William H. Keith Jr. that focus on the United Star Marine Corps. The trilogy is the sequel to the Heritage Trilogy and the Legacy Trilogy.
Ancient astronauts have been addressed frequently in science fiction and horror fiction. Occurrences in the genres include:
Star Born is a science fiction novel by American writer Andre Norton, first published in 1957 by World Publishing Company of Cleveland. This is the sequel to The Stars Are Ours! and continues that adventure three generations on.
Manhunter is a role-playing game originally published by Kingslayer Productions in 1988.
The Boy Who Would Live Forever is a science fiction novel by the American writer Frederik Pohl. It was published in 2004 by Tor. It is about intrigues involving one of Pohl's recurring creations, the Heechee universe. The Heechee are a fictional alien race which developed advanced technologies, including interstellar space travel, but then disappeared. In the novel, humans use abandoned Heechee starships to explore space, while the Heechee aliens hide from a mysterious foe, the Kugel, in a black hole, all the while pursued by hate-crazed humans who are Heechee hunters.
