Playing With / Absent Aliens

Basic Trope: Humans are the only known intelligent form of life in the universe.
  • Straight: In the early 22nd century, humanity has ventured far into the Milky Way and discovered no intelligent life forms, although there are clearly signs of extraterrestrial life, but those extraterrestrials in question are microscopic.
  • Exaggerated: They can't even find even the most primitive single-celled organisms, despite sending orbital probes and scientific rovers to every habitable planet. All of life itself has only evolved on one planet - Earth.
  • Downplayed:
    • Alien life has evolved to the level of animals at most, but they're non-sapient.
    • Every now and then, people allege to have seen UFOs or even alien beings, but they have no solid evidence of those claims.
  • Justified:
    • Human space travel is in its infancy, and we haven't had time to find them yet.
    • The odds of contacting intelligent life forms are so low that, even if they are there, it might take a million years to find one.
    • There used to be extraterrestrial civilizations, but they went extinct somehow.
  • Inverted: The universe is full of aliens, but humans don't exist.
  • Subverted: Humans finally discover an alien civilization, and quickly make First Contact.
  • Double Subverted: The 'alien civilization' was actually a long lost human colony.
  • Zig Zagged: The starship Lazarus searches 1000 earth-like planets for intelligent life. Some of them offer false leads, but all of them are uninhabited. That is until the last planet they look actually does support an alien species, but it is non-sapient. However they find out the intelligent aliens were posing as non-sapient to see how the humans would treat them. Then it turns out that they are actually highly evolved humans, and the starship's crew had experienced 50 million years worth of Time Dilation.
  • Parodied:
  • Averted: There are plenty of aliens in the universe.
  • Enforced: Aliens are avoided to save on a show's budget.
  • Lampshaded: "Don't be ridiculous, Bob. There's no way we'll find aliens on this mission."
  • Invoked:
    • Humans wanted a universe without aliens, so we killed them all.
    • We know they're there, but avoid making contact with them.
  • Exploited: If every planet is uninhabited, then we shouldn't feel too guilty about taking over the universe.
  • Defied: A scientist, bored of his own species or horrified about the fact that there aren't any other sapients, creates alien life in the lab.
  • Discussed: "It's strange to think that we really are alone in the universe."
  • Conversed: "It's refreshing to see a sci-fi show without those low budget aliens."
  • Played For Drama: The fact that the universe is empty of non-human life is viewed as highly disturbing — especially when human explorers start finding the ruins of extinct alien races, implying something wiped them out...

Go back to Absent Aliens if you like, but you won't find any intelligent life there.
http://tvtropes.org/pmwiki/pmwiki.php/PlayingWith/AbsentAliens