"dimension". For this reason, ufologists refer to this idea as "Interdimensional Hypothesis". According to this theory, put forth by ufologists such as Jacques Vallee, other beings don't really travel long distances to earth but are right next door in different realities or states of time alongside our own. Perhaps the aliens being witnessed are in fact human civilization advanced hundreds of years. Many have come to this conclusion because interstellar travel is scientifically impractical as far as anyone can explain. This hypothesis may also explain why UFO's seem to pop in and out of existence instead of flying out of view. Some witnesses have even claimed that these flying objects materialize with a ghost-like transparency rather than a solid appearance.
While both hypotheses offer some perception into the reason why people may see unidentified flying objects, the debate continues. Do aliens really travel from distances far beyond using technologies that scientists cannot yet comprehend, or do they simply drop into our universe from a universe next door? What if humans could learn and mimic the technology, visit other parallel universes unlike our own, and obtain the answers we've been seeking for so long? What if these interpretations also explain other paranormal events that seem to take place in the here and now?
Maybe the paranormal wouldn't be so...paranormal.