There are many competing theories about the origins and nature of UFOs. For example, researchers Brad Steiger and Sherry Hansen Steiger have a list of seventeen theories at their website. In UFO: The Complete Sightings (1995) by Peter Brookesmith, there is a list of nine theories. Further, these theories are often categorized. In The Mammoth Encyclopedia of Extraterrestrial Encounters (2001) edited by Ronald D. Story, the subject is divided into “conventional (unintelligent)” and “unconventional (intelligent)” encounters.
Others use terms like “natural” versus “unnatural,” “material” versus “immaterial,” or “physical” versus “non-physical” to categorize, or break down, the UFO situation. Choose whatever terms feel best to you. Below is a simplified breakdown that gives three categories of UFO manifestation:
• External UFO theories suggest that UFOs are phenomena that originate outside of the human mind, whether physical, ethereal, or inter-dimensional.
• Internal UFO theories suggest that UFO phenomena originate within the human mind—that they are psychological, spiritual, and/or inter-dimensional.… Read the rest