The Interdimensional Hypothesis: Vallée, Keel and UFOs Beyond Space

Jacques Vallée, a French-born astronomer and computer scientist who worked with J. Allen Hynek, began as a careful statistician of UFO reports. In Passport to Magonia (1969), he compared modern close encounter accounts with older folklore about fairies, elves, demons and religious apparitions, and argued that the similarities were striking: abductions, missing time, strange beings and gifts of odd food appeared in both.

Vallée concluded that the UFO phenomenon was not new, and that it might be better understood as a long-running phenomenon that adapts its appearance to each culture rather than as a recent wave of space visitors. In later books, including The Invisible College (1975), he proposed that it might act as a kind of control system shaping human belief.

The American journalist John Keel reached similar conclusions by a different route. In UFOs: Operation Trojan Horse (1970), he argued that UFOs were not physical spacecraft but manifestations of what he called ultraterrestrials, entities able to change form and to deceive witnesses. His later book The Mothman Prophecies (1975), about strange events around Point Pleasant, West Virginia, in 1966 and 1967, brought these ideas to a wide audience and was adapted into a 2002 film.

Keel’s work was more speculative and more literary than Vallée’s, and it mixed UFOs with poltergeists, monsters and prophecy. It helped create the broad high-strangeness tradition in which UFOs are treated as part of a wider paranormal field.

In a 1990 paper in the Journal of Scientific Exploration, Vallée set out five arguments against the extraterrestrial explanation of UFOs. Among them: the number of reported close encounters is far greater than a physical survey of Earth would require; the beings described are mostly humanoid and breathe our air; abduction behaviour seems inconsistent with advanced science; and similar phenomena appear throughout history.

Supporters of the extraterrestrial hypothesis reply that these observations are equally consistent with misperception, cultural shaping and hoaxes, which would also explain the humanoid forms and the folklore parallels. Sceptics add that the interdimensional hypothesis is even harder to test than the extraterrestrial one, because it allows the phenomenon to behave in any way at all.

In physics, a dimension is simply an independent direction in which something can be measured. Theories with extra spatial dimensions go back to the work of Theodor Kaluza and Oskar Klein in the 1920s, and they are central to string theory, which in its standard forms requires ten or eleven dimensions. In most versions the extra dimensions are curled up at scales far too small to observe.

In 1998 and 1999, physicists proposed models in which extra dimensions could be larger or warped, as described for general readers by Lisa Randall in Warped Passages (2005). Experiments at the Large Hadron Collider have searched for signatures of such dimensions and have not found them. None of these theories describes beings or vehicles travelling between dimensions; that popular use of the word borrows the language of physics without its mathematics.

The interdimensional idea has become more visible in recent years. Some people associated with U.S. government interest in UAP, and research into places such as Skinwalker Ranch, have discussed paranormal or consciousness-related interpretations alongside physical ones. The religious studies scholar Diana Walsh Pasulka, in American Cosmic (2019), examined how UFO belief functions like a new religious framework, drawing partly on Vallée’s ideas.

Official studies have not endorsed any of these interpretations. NASA’s 2023 UAP study and AARO’s 2024 historical report focused on conventional data and found no evidence that UAP are non-human in origin, whether extraterrestrial or otherwise.