Interdimensional Hypothesis (IDH)

The interdimensional hypothesis (IDH) proposes that the UFO phenomenon originates from a coexisting, non-physical reality or "control system" operating alongside our own, rather than from literal interstellar spacecraft crossing physical space from another star system. Its two principal architects, Jacques Vallée and John Keel, arrived at the idea independently through the same route: both spent years cataloguing high-strangeness cases — occupants that seemed to appear and vanish, absurd or internally contradictory physics, encounters that behaved more like folklore or dream logic than hardware malfunction — and concluded that a purely mechanical extraterrestrial-spacecraft model simply didn't fit what the strangest cases actually described. Vallée buttressed the theory with centuries of pre-modern fairy and apparition lore showing the same structural patterns, published in "Passport to Magonia" (1969); Keel developed his own, stranger "ultraterrestrial" variant in "The Mothman Prophecies" (1975) after his ground investigation of the 1966-67 Point Pleasant sightings. IDH remains a minority position within ufology relative to the more straightforward extraterrestrial hypothesis, but it commands serious respect precisely because its proponents were career researchers, not fringe figures, and because it directly addresses cases the ETH struggles with — the ones exhibiting genuine high strangeness rather than a simple, physically plausible craft sighting.