The subject of aliens and extraterrestrials has long fascinated us with hundreds of books, movies and TV programs about the subject of alien beings. Are they truly space travelers? If they exist, what are they and where do they come from? We look at the 5 most interesting theories about aliens.

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    Hollow Earth Theory

    The Hollow Earth theory hold that there is not a molten core at the center of our planet but a sophisticated civilization living below the crust of the earth. There are alleged to be certain spots in the globe where the subterranean dwellers can access the surface. This theory would account of the phenomenon of USOs or Unidentified Submerged Objects.

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    Visitors From Our Future

    What if the visitors were not from planets far, far away but are time travelers from our own future. This theory explains why there has been no contact. The future visitors know they can have no interaction with ancestors from the past.

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    Reptilians

    Those who believe in Reptilians, including the theory's leading proponent, David Icke, assert that lizard-like visitors take the form of humans and are secretly in charge of world affairs.

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    Ancient Aliens

    This is the theory that spawned a History channel series. The ancient aliens theory really took off in the last 1960s with the publication of the book, 'Chariots of the Gods?'. This theory holds that ancient alient vistors set the stage for civilization and technological learning on Earth.

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    Visitors from Different Dimensions

    It could take hundreds of human lifetimes to travel between galaxies. How then could outer space visitors travel to the earth? The Different Dimension theory talks about bending time and space and traveling between dimensions to traverse insurmountable distances.