Although the extraterrestrial hypothesis (ETH) as a phrase is a comparatively new concept, one which owes much to the flying saucer sightings of the 1940s–1960s, its origins can be traced back to a number of earlier events, such as the now-discredited Martian canals and ancient Martian civilization promoted by astronomer Percival Lowell, popular culture including the writings of H. G. Wells and fellow science fiction pioneers such as Edgar Rice Burroughs, who likewise wrote of Martian civilizations, and even to the works of figures such as the Swedish philosopher, mystic and scientist Emanuel Swedenborg, who promoted a variety of unconventional views that linked other worlds to the afterlife.
[8] In the early part of the twentieth century, Charles Fort collected accounts of anomalous physical phenomena from newspapers and scientific journals, including many reports of extraordinary aerial objects.
Fort's reports of aerial phenomena were frequently cited in American newspapers when the UFO phenomenon first attracted widespread media attention in June and July 1947.
An early example of speculation over extraterrestrial visitors can be found in the French newspaper Le Pays, which on June 17, 1864, published a story about two American geologists who had allegedly discovered an alien-like creature, a mummified three-foot-tall hairless humanoid with a trunk-like appendage on its forehead, inside a hollow egg-shaped structure.
"[11] From the 1920s, the idea of alien visitation in space ships was commonplace in popular comic strips and radio and movie serials, such as Buck Rogers and Flash Gordon.
In particular, the Flash Gordon serials have the Earth being attacked from space by alien meteors, ray beams, and biological weapons.
"[14][15][16][17] When the 1947 flying saucer wave hit the United States, there was much speculation in the newspapers about what they might be in news stories, columns, editorials, and letters to the editor.
Senator Glen Taylor of Idaho commented, "I almost wish the flying saucers would turn out to be space ships from another planet," because the possibility of hostility "would unify the people of the earth as nothing else could."
If the present discs weren't secret Army weapons, he suggested they could be vehicles from Mars, or other planets, or maybe even "things out of other dimensions of time and space.
"[18] Other articles brought up the work of Charles Fort, who earlier in the twentieth century had documented numerous reports of unidentified flying objects that had been written up in newspapers and scientific journals.
Various popular theories began to quickly proliferate in press articles, such as secret military projects, Russian spy devices, hoaxes, optical illusions, and mass hysteria.
According to journalist Edward R. Murrow, the ETH as a serious explanation for "flying saucers" did not earn widespread attention until about 18 months after Arnold's sighting.
In 1948, Project Sign concluded without endorsing any unified explanation for all UFO reports, and the ETH was rejected by USAF Chief of Staff General Hoyt Vandenberg, citing a lack of physical evidence.
Vandenberg dismantled Project Sign, and with this official policy in place, subsequent public Air Force reports concluded, that there was insufficient evidence to warrant further investigation of UFOs.
[30] The scientific community has shown very little support for the ETH, and has largely accepted the explanation that reports of UFOs are the result of people misinterpreting common objects or phenomena, or are the work of hoaxers.
[42] We need to frame the current UAP/UFO question with the same level of active inquiry, one involving experts from academia in disciplines including astronomy, meteorology and physics, as well as industry and government professionals with knowledge of military aircraft, remote sensing from the ground and satellite observations.
Participants would need to be agnostic toward any specific explanations with a primary goal of collecting enough data — including visual, infrared, radar and other possible observations — to eventually allow us to deduce the identity of such UAP.
Aliens are the subject of numerous urban legends, including claims that they have long been present on earth or that they may be able to assist humans in resolving certain issues.
[45] Other private or government studies, some secret, have concluded in favor of the ET hypothesis, or have had members who disagreed in contravention with official conclusions reached by the committees and agencies to which they belonged.