Invisible Aliens: Difference between revisions

* In one of the stories in ''[[Sherlock Holmes]] in Orbit'', {{spoiler|reviving Holmes after he went over the Reichenbach Falls put Earth out of quantum synch with the rest of the universe.}}

* In ''The Engines of God'' and later books by Jack McDevitt, the galaxy seems to naturally produce things called "omega clouds" every 8000 years or so, strange clouds that are sent out in a wave from the galactic center and can look for and track excessive, clearly artificial regularity on planets—in other words, square and rectangular buildings and constructions of other shapes that are too regular and precise to appear in nature—and crash into them, sometimes catastrophically, to eliminate societies that have advanced much beyond the Stone Age. Some characters theorize that an omega cloud may have inspired the legends of Sodom and Gomorrah when it destroyed an early Earth civilization, since the relative timing fits with when the clouds should have last been through.

* The ''[[Berserker (Literature)|Berserker]]'' series by [[Fred Saberhagen]] has organic life threatened by the eponymous [[Killer Robot]]s, who were the [[Forgotten Superweapon|Doomsday Device]] released by the losing side of an intergalactic war. Only a few scrappy (not [[The Scrappy]]) species manage to survive, including Earth-Descended, or E.D., life.

* The ''[[Honor Harrington]]'' novels state that humanity has, in the two millennia they have been tooling around the galaxy, encountered approximately twelve alien races. However, though there is at least one extinct race that achieved inter-stellar flight, the technology level of the other species is never mentioned. Alien races show up only as flavoring (the Sphinxian treecat, shown in almost every story) and a minor background element in two stories. For all practical intents and purposes, it is an all-human galaxy.