The Interdimensional Hypothesis (IDH) is a theory that suggests that some UFO sightings and paranormal phenomena may be explained by the existence of other dimensions or parallel universes. The origins of the IDH can be traced back to the early days of UFO research, with several notable figures in the field proposing variations of this hypothesis.

One of the earliest proponents of the IDH was Meade Layne, who founded the Borderland Sciences Research Foundation in 1945. Layne proposed the idea of "Ether Ships," which he believed were interdimensional vehicles that could be seen by humans when they entered our three-dimensional reality.

Another influential figure in the development of the IDH was John Keel, who is best known for his book "The Mothman Prophecies." Keel proposed the idea of "Ultraterrestrials," which he described as beings from other dimensions that were able to interact with our reality in various ways.

J. Allen Hynek, a prominent astronomer and UFO researcher, also explored the idea of interdimensional beings in his later years. Hynek proposed that some UFO sightings could be explained by the existence of "window areas," which were locations where other dimensions could intersect with our own.

However, perhaps the most well-known proponent of the IDH is Jacques Vallée, a French-American computer scientist and ufologist. Vallée has written extensively on the subject of interdimensional beings, proposing that some UFO sightings and paranormal phenomena may be related to the existence of other dimensions.

Vallée has suggested that there may be a connection between UFO sightings and paranormal phenomena, such as encounters with beings that are described as ghosts or demons. He has also proposed that the phenomenon of crop circles could be related to the IDH.

Some researchers have suggested that the phenomenon of poltergeists could be explained by interdimensional beings or entities that are able to manipulate physical matter.

Crop circles are another phenomenon that has been linked to the IDH. These intricate designs, which began to appear in the UK in the 1970s, have been attributed to a variety of causes, including hoaxes and natural phenomena. However, some researchers have suggested that they may be created by interdimensional beings that are able to manipulate physical matter using advanced technology from other dimensions.

Despite the controversy surrounding the IDH, there continue to be modern-day proponents of this theory. Some researchers have pointed to recent advances in fields such as quantum mechanics and string theory as evidence that other dimensions and parallel universes may exist.