- A scientific introduction -
Started in 2009.
This article is an effort to create an extended and more concise version from the articles that relate to the Wikipedia: Ufology articles. This version also contains information that was deleted or scattered. Aditional sections are recovered from page history sections and other (deleted) pages of Wikipedia and are included here, because I think they contain relevant information and provide a more consistent and broader scope of vision, often entitled "unscientific" or "science-fiction" by wikipedia. Already this version is a lot more informative...
Ufology in a narrow sense is the science and study of unidentified flying object (UFO) reports and associated evidence. In a broader sense ufology is also used to refer to the study of extraterrestrial aliens and all subject matter related to it.
Common explanations for UFO sightings are:
- The man-made craft hypothesis: UFOs are top secret Russian or American aircraft
- Time travel hypothesis: UFOs are time machines or vehicles built in a future time
- The Extraterrestrial Visitation Hypothesis (ETH): UFOs are alien spacecrafts
- The Extraterrestrial Energyzoa Hypothesis (ETZH): UFOs represent as yet uncatalogued living beings
- The Interdimensional Hypothesis (IDH): UFOs are paranormal activities - the results of objects crossing over from other dimensions
- The Cosmic Trickster and Ultraterrestrial hypothesis: UFO's have an objective reality, though of a kind humans cannot comprehend or understand
- The Paranormal/Occult Hypothesis: UFOs are supernatural beings
Similarly, skeptics usually propose one of the following explanations:
- The Psychological-Social Hypothesis: UFO sightings are hallucinations or fantasies
- The Unknown Natural Phenomena hypothesis: UFOs are unkown natural phenomena (e.g. ball lightning, sprites)
- The Meteorological hypothesis: UFOs are instances of visible combustion of a fuel (e.g., natural gas) inside an atmospheric vortex
- The Tectonic Strain hypothesis: UFOs are earthquake lights
- The Autokinetic effect hypothesis
- The "shiny-bodied insects" hypothesis
While Ufology is not regarded as an academic research program by most academic Universities, UFOs have been subject to various investigations ever since the 1920s, varying widely in scope and scientific rigor. Governments or independent academics in the United States, Canada, the United Kingdom, France, Belgium, Sweden, Brazil, Mexico, Spain, and the Soviet Union are known to have investigated UFO reports at various times. No national government has ever officially and publicly asserted that UFOs represent any form of alien intelligence. However, several governments have displayed interest in UFO phenomena. Perhaps the best known study was Project Blue Book, previously Project Sign and Project Grudge, conducted by the United States Air Force from 1947 until 1969. Other notable investigations include the Robertson Panel (1953), the Brookings Report (1960), the Condon Committee (1966–1968), the Project Twinkle investigation into green fireballs (1948–1951), the Sturrock Panel (1998), and the French GEIPAN (1977-) and COMETA (1996–1999) study groups.
Background and status as a field
Ufology has never been fully embraced by academia as a scientific field of study even though it was, in the early days, the subject of large scale scientific studies that produced reports described to follow.  Prior to August, 2008,  one could not obtain a "ufology" degree from any college or university, though there have been a few college or university courses on the subject, often from a folklore perspective.
Ufologists vary from fringe proponent David Icke to respected mainstream scientists like Peter A. Sturrock, J. Allen Hynek, Jacques Vallee, James E. McDonald, or Auguste Meessen, some of whom argue that UFO reports are as worthy of study as any topic, and deserve case-by-case analysis using the scientific method. Debunkers include Philip Klass and Dr. Donald Menzel.
Not all ufologists believe that UFOs are necessarily extraterrestrial spacecraft, or even that they are objective physical phenomena. Even those UFO cases that are exposed as hoaxes, or found to be delusions or misidentifications may still be worthy of serious study from a psychosocial point of view.
Dr. Carl Sagan was quite skeptical of any extraordinary answer to the UFO question, but in 1969, he co-organised a symposium on the subject, thinking that science had unfairly neglected the UFO question. However, Westrum wrote that "Sagan spent very little time researching UFOs ... he thought that little evidence existed to show that the UFO phenomenon represented alien spacecraft and that the motivation for interpreting UFO observations as spacecraft was emotional".  Sagan's college classmate Stanton T. Friedman criticized Sagan for ignoring evidence, such as "600-plus UNKNOWNS of Project Blue Book Special Report No. 14". Friedman refers to a table in Project Blue Book Special Report No. 14 that he says "shows that the better the quality of the sighting, the more likely it was to be an 'unknown', and the less likely it was to be listed as 'insufficient information'"  (p. 42). Friedman argued that this empirical data directly contradicts Sagan's claim in Other Worlds, that the "reliable cases are uninteresting and the interesting cases are unreliable. Unfortunately there are no cases that are both reliable and intesting".
In her critique of the Condon Report, Diana Palmer Hoyt notes that "The UFO problem seems to bear a closer resemblance to problems in meteorology than in physics. The phenomena are observed, occur episodically, are not reproducible, and in large part, are identified by statistical gathering of data for possible organization into patterns. They are not experiments that can be replicated at will at the laboratory bench under controlled conditions." (see external links below)
Along these lines, Peter A. Sturrock suggests that UFO studies should be compartmentalized — as are most scientific endeavors — into at least "the following distinct activities:
- Field investigations leading to case documentation and the measurement or retrieval of physical evidence;
- Laboratory analysis of physical evidence;
- The systematic compilation of data (descriptive and physical) to look for patterns and so extract significant facts;
- The analysis of compilations of data (descriptive and physical) to look for patterns and so extract significant facts;
- The development of theories and the evaluation of those theories on the basis of facts." 
Study of UFO sightings has yielded results applicable to other fields, such as in weather phenomena (see Hessdalen) and in human perception, such as the study lead by the SOBEPS for the Belgian flap in 1989-'90 or the studies of the GEPAN/SEPRA in France.
The lack of acceptance of ufology by mainstream academia as a field of study means that people can claim to be "UFO researcher", without the sorts of scientific consensus building and, in many cases peer review, that otherwise shape and influence scientific paradigms. This has allowed many to stake out territory and disseminate claims, information and analysis of widely varying rigor and quality.
Some ufologists, such as Stanton Friedman (2008), consider the general attitude of mainstream academics as arrogant and dismissive, or bound to a rigid world view that disallows any evidence contrary to previously held notions. Others charge that mainstream rejection of UFO evidence is a classic case of pathological science. Astronomer and ufologist J. Allen Hynek's famous comment regarding this subject is, "Ridicule is not part of the scientific method and people should not be taught that it is."  Another comment by Hynek regarding the frequent dismissal of UFO reports by astronomers was, "Close questioning revealed they) knew nothing of the actual sightings, of their frequency or anything much about them, and therefore cannot be taken seriously. This is characteristic of scientists in general when speaking about subjects which are not in their own immediate field of concern." 
Critics like Robert Sheaffer have accused ufology of having a "credulity explosion." He claims a trend of increasingly sensational ideas steadily gaining popularity within ufology. Sheaffer remarked "the kind of stories generating excitement and attention in any given year would have been rejected by mainstream ufologists a few years earlier for being too outlandish." 
Whether or not this view has a basis in evidence, James McDonald long ago expressed the view that extreme groups undermined serious scientific investiation, stating that a "bizarre "literature" of pseudo-scientific discussion" on "spaceships bringing messengers of terrestrial salvation and occult truth" had been "one of the prime factors in discouraging serious scientists from looking into the UFO matter to the extent that might have led them to recognize quickly enough that cultism and wishful thinking have nothing to do with the core of the UFO proglem." In the same statement, McDondald said that 
"Again, one must here criticize a good deal of armchair-researching (done chiefly via the daily newspapers that enjoy feature-writing the antics of the more extreme of such subgroups). A disturbing number of prominent scientists have jumped all too easily to the conclusion that only the nuts see UFOs." 
Modern UFO science has three traceable roots: the late 19th century "mystery airships" reported in the newspapers of western United States, "foo fighters" reported by Allied airmen during World War II, and the Kenneth Arnold "flying saucer" sighting near Mt. Rainier, Washington on June 24, 1947.  UFO reports between "The Great Airship Wave" and the Arnold sighting were limited in number compared to the post-war period: notable cases include reports of "ghost fliers" in Europe and North America during the 1930s and the numerous reports of "ghost rockets" in Scandinavia (mostly Sweden) from May to December 1946.  Media hype in the late 1940s and early 1950s following the Arnold sighting brought the concept of flying saucers to the public audience. 
As the public's preoccupation in UFOs grew, along with the number of reported sightings, the United States military began to take notice of the phenomenon. The UFO explosion of the early post-war era coincides with the escalation of the Cold War and the Korean War.  The U.S. military feared that secret aircraft of the Soviet Union, possibly developed from captured German technology, were behind the sightings.  If correct, the craft causing the sightings were thus of importance to national security  and of need of systematic investigation. By 1952, however, the official US government interest in UFOs began to fade as the USAF projects Sign and Grudge concluded, along with the CIA's Robertson Panel that UFO reports indicated no direct threat to national security. The government's official research into UFOs ended with the publication of the Condon Committee report in 1969, which concluded that the study of UFOs in the past 21 years had achieved little, if anything, and that further extensive study of UFO sightings was unwarranted. It also recommended the termination of the USAF special unit Project Blue Book. 
As the U.S. government ceased officially studying UFO sightings, the same became true for most governments of the world. A notable exception is France, which still maintains the GEIPAN,  formerly known as GEPAN (1977–1988) and SEPRA (1988–2004), a unit under the French Space Agency CNES. During the Cold War, British,  Canadian,  Danish,  Italian,  and Swedish  governments have each collected reports of UFO sightings. Britain's Ministry of Defence ceased accepting any new reports as of 2010. 
The Air Force's Project Blue Book files indicate that approximately 1% of all their reports came from amateur and professional astronomers or other users of telescopes (such as missile trackers or surveyors). In the 1970s, astrophysicist Peter A. Sturrock conducted two surveys of the American Institute of Aeronautics and Astronautics and American Astronomical Society. About 5% of the members polled indicated that they had had UFO sightings.   In 1980, a survey of 1800 members of various amateur astronomer associations by Gert Helb and astronomer J. Allen Hynek of the Center for UFO Studies (CUFOS) found that 24% responded "yes" to the question "Have you ever observed an object which resisted your most exhaustive efforts at identification?" 
Astronomer Clyde Tombaugh, who admitted to 6 UFO sightings , including 3 green fireballs supported the Extraterrestrial hypothesis (ETH) for UFOs and stated he thought scientists who dismissed it without study were being "unscientific." Another astronomer was Dr. Lincoln LaPaz, who had headed the Air Force's investigation into the green fireballs and other UFO phenomena in New Mexico. LaPaz reported 2 personal sightings, one of a green fireball, the other of an anomalous disc-like object. Even later UFO debunker Dr. Donald Menzel filed a UFO report in 1949. 
See Wikipedia: List of Ufologists
Various public scientific studies over the past half century have examined UFO reports in detail. None of these studies have officially concluded that any reports are caused by extraterrestrial spacecraft (e.g., Seeds 1995:A4). Some studies were neutral in their conclusions, but argued the inexplicable core cases called for continued scientific study. Examples are the Sturrock Panel study of 1998 and the 1970 AIAA review of the Condon Report. Other private or governmental studies, some secret, have concluded in favor of the ETH, or have had members who disagreed with the official conclusions. The following are examples of such studies and individuals:
- One of the earliest government studies to come to a secret ETH conclusion was Project Sign, the first official Air Force UFO investigation. In 1948, they wrote a top-secret intelligence estimate to that effect. The Air Force Chief of Staff ordered it destroyed. The existence of this suppressed report was revealed by several insiders who had read it, such as astronomer and USAF consultant Dr. J. Allen Hynek and Edward J. Ruppelt, the first head of the USAF's Project Blue Book. (Ruppelt, Chapt. 3)
- An early U.S. Army study, of which little is known, was called the Interplanetary Phenomenon Unit (IPU). In 1987, British UFO researcher Timothy Good received a letter confirming the existence of the IPU from the Army Director of Counter-intelligence, in which it was stated, "...the aforementioned Army unit was disestablished during the late 1950s and never reactivated. All records pertaining to this unit were surrendered to the U.S. Air Force Office of Special Investigations in conjunction with operation BLUEBOOK." The IPU records have never been released. 
- In 1967, Greek physicist Paul Santorini, a Manhattan Project scientist, publicly stated that a 1947 Greek government investigation that he headed into the European Ghost rockets of 1946 quickly concluded that they were not missiles. Santorini claimed the investigation was then quashed by military officials from the U.S., who knew them to be extraterrestrial, because there was no defense against the advanced technology and they feared widespread panic should the results become public. 
- A 1948 Top Secret USAF Europe document (at right) states that Swedish air intelligence informed them that at least some of their investigators into the ghost rockets and flying saucers concluded they had extraterrestrial origins: "...[Flying saucers] have been reported by so many sources and from such a variety of places that we are convinced that they cannot be disregarded and must be explained on some basis which is perhaps slightly beyond the scope of our present intelligence thinking. When officers of this Directorate recently visited the Swedish Air Intelligence Service... their answer was that some reliable and fully technically qualified people have reached the conclusion that 'these phenomena are obviously the result of a high technical skill which cannot be credited to any presently known culture on earth.' They are therefore assuming that these objects originate from some previously unknown or unidentified technology, possibly outside the earth." 
- Various European countries conducted a secret joint study in 1954, also concluding that UFOs were extraterrestrial. This study was revealed by German rocketry pioneer Hermann Oberth, a member of the study, who also made many public statements supporting the ETH.
- In 1958, Brazil's main UFO investigator, Dr. Olavo T. Fuentes wrote a letter to the American UFO group APRO summarizing a briefing he had received from two Brazilian Naval intelligence officers. Fuentes said he was told that every government and military on Earth was aware that UFOs were extraterrestrial craft and there was absolute proof of this in the form of several crashed craft. The subject was classified Top Secret by the world's militaries. The objects were deemed dangerous and hostile when attacked, many planes had been lost, and it was generally believed that Earth was undergoing an invasion of some type, perhaps a police action to keep us confined to the planet. This information had to be withheld from the public by any means necessary because of the likelihood of widespread panic and social breakdown. 
- During the height of the flying saucer epidemic of July 1952, including highly publicized radar/visual and jet intercepts over Washington, D.C., the FBI was informed by the Air Force Directorate of Intelligence that they thought the "flying saucers" were either "optical illusions or atmospheric phenomena" but then added that, "some Military officials are seriously considering the possibility of interplanetary ships." (See: FBI document Source: » Rense)
- The CIA started their own internal scientific review the following day. Some CIA scientists were also seriously considering the ETH. An early memo from August was very skeptical, but also added, "...as long as a series of reports remains 'unexplainable' (interplanetary aspects and alien origin not being thoroughly excluded from consideration) caution requires that intelligence continue coverage of the subject." A report from later that month was similarly skeptical but nevertheless concluded "...sightings of UFOs reported at Los Alamos and Oak Ridge, at a time when the background radiation count had risen inexplicably. Here we run out of even 'blue yonder' explanations that might be tenable, and we still are left with numbers of incredible reports from credible observers." A December 1952 memo from the Assistant CIA Director of Scientific Intelligence (O/SI) was much more urgent: "...the reports of incidents convince us that there is something going on that must have immediate attention. Sightings of unexplained objects at great altitudes and traveling at highs speeds in the vicinity of U.S. defense installation are of such nature that they are not attributable to natural phenomena or known types of aerial vehicles." Some of the memos also made it clear that CIA interest in the subject was not to be made public, partly in fear of possible public panic. (Good,331-335)
- The CIA organized the January 1953 Robertson Panel of scientists to debunk the data collected by the Air Force's Project Blue Book. This included an engineering analysis of UFO maneuvers by Blue Book (including a motion picture film analysis by Naval scientists) that had concluded UFOs were under intelligent control and likely extraterrestrial. 
- Extraterrestrial "believers" within Project Blue Book including Major Dewey Fournet, in charge of the engineering analysis of UFO motion. Director Edward J. Ruppelt is also thought to have held these views, though expressed in private, not public. Another defector from the official Air Force party line was consultant Dr. J. Allen Hynek, who started out as a staunch skeptic. After 20 years of investigation, he changed positions and generally supported the ETH. He became the most publicly known UFO advocate scientist in the 1970s and 1980s.
- The first CIA Director, Vice Admiral Roscoe H. Hillenkoetter, stated in a signed statement to Congress, also reported in the New York Times, February 28, 1960, "It is time for the truth to be brought out... Behind the scenes high-ranking Air Force officers are soberly concerned about the UFOs. However, through official secrecy and ridicule, many citizens are led to believe the unknown flying objects are nonsense... I urge immediate Congressional action to reduce the dangers from secrecy about unidentified flying objects." In 1962, in his letter of resignation from NICAP, he told director Donald Keyhoe, "I know the UFOs are not U.S. or Soviet devices. All we can do now is wait for some actions by the UFOs." 
- Although the 1968 Condon Report came to a negative conclusion (written by Condon), it is known that many members of the study strongly disagreed with Condon's methods and biases. Most quit the project in disgust or were fired for insubordination. A few became ETH supporters. Perhaps the best known example is Dr. David Saunders, who in his 1968 book UFOs? Yes lambasted Condon for extreme bias and ignoring or misrepresenting critical evidence. Saunders wrote, "It is clear... that the sightings have been going on for too long to explain in terms of straightforward terrestrial intelligence. It is in this sense that ETI (Extra Terrestrial Intelligence) stands as the `least implausible' explanation of `real UFOs'." 
- Nick Pope, a Higher Scientific Officer in the UK MOD who was responsible for the UK government UFO desk for a number of years, is an advocate of the ETH based on the inexplicable cases he reviewed, such as the Rendlesham UFO incident, although the British government has never made such claims.
- Jean-Jacques Velasco, the head of the official French UFO investigation SEPRA, wrote a book in 2005 saying that 14% of the 5800 cases studied by SEPRA were utterly inexplicable and extraterrestrial in origin.  Yves Sillard, the head of the new official French UFO investigation GEIPAN and former head of the French space agency CNES, echoes Velasco's comments and adds the U.S. is guilty of covering up this information.  Again, this isn't the official public posture of SEPRA, CNES, or the French government. (CNES recently announced that their 5800 case files will be placed on the Internet starting March 2007.)
- The 1999 French COMETA committee of high-level military analysts/generals and aerospace engineers/scientists declared the ETH was the best hypothesis for the unexplained cases. 
- Panel discussion on November 12, 2007 : On November 12, 2007, Former Arizona Governor Fife Symington moderated a panel of former high-ranking government, aviation and military officials from seven countries at the National Press Club. , , , , , 
Astrophysicist Peter A. Sturrock suggests that a lack of funding is a major factor in the institutional disinterest in UFO’s: "If the Air Force were to make available, say, $50 million per year for ten years for UFO research, it is quite likely that the subject would look somewhat less disreputable ... however, an agency is unlikely to initiate such a program at any level until scientists are supportive of such an initiative. We see that there is a chicken-and-egg program. It would be more sensible, and more acceptable to the scientific community, if research began at a low level." 
UFOs in popular culture
UFOs constitute a widespread international cultural phenomenon of the last half-century. Gallup polls rank UFOs near the top of lists for subjects of widespread recognition. In 1973, a survey found that 95 percent of the public reported having heard of UFOs, whereas only 92 percent had heard of US President Gerald Ford in a 1977 poll taken just nine months after he left the White House. (Bullard, 141) A 1996 Gallup poll reported that 71 percent of the United States population believed that the government was covering up information regarding UFOs. A 2002 Roper poll for the Sci Fi channel found similar results, but with more people believing UFOs were extraterrestrial craft. In that latest poll, 56 percent thought UFOs were real craft and 48 percent that aliens had visited the Earth. Again, about 70 percent felt the government was not sharing everything it knew about UFOs or extraterrestrial life. Another effect of the flying saucer type of UFO sightings has been Earth-made flying saucer craft in space fiction, for example the Earth spacecraft Starship C-57D in Forbidden Planet, the Jupiter Two in Lost in Space, and the saucer section of the USS Enterprise in Star Trek, and many others. For an excellent analysis of the interrelationship between popular culture and UFOs consult the research by psychologist Armando Simon, especially his contribution in Richard Haines' book, UFO Phenomena and the Behavioral Scientist.
See Wikipedia: UFOs in Fiction
- United States Air Force Project Blue Book: Small, public Air Force UFO investigation, from 1952 until discontinued in 1969. Preceded by Project Sign (1947–1948) and Project Grudge (1948–1952).
- Aerial Phenomena Research Organization (APRO) (1952–1988): Early, national U.S. civilian research organization with many PhD consulting scientists.
- National Investigations Committee On Aerial Phenomena (NICAP)(1956–1980), Early, national U.S. civilian research organization, very large and powerful at one time, with many scientists and military consultants.
- Mutual UFO Network (MUFON): Large, international, U.S. based civilian research organization stressing field investigations and data collection. MUFON is the largest civilian UFO research group in the United States today.
- Center for UFO Studies (CUFOS): Founded by Project Blue Book consultant, astronomer and ufologist J. Allen Hynek; stresses scientific investigations; large archives, including old NICAP files.
- Fund for UFO Research: Funds scientific UFO research; many consulting PhD scientists; does photoanalysis.
- National Institute of Discovery Science (NIDS): Private, somewhat clandestine organization with insider government scientists and military people stressing scientific forensic analysis of UFO and paranormal phenomena.
- Phenomena Research Australia (PRA): This group has grew out of the Aeronautical Research Laboratory – Melbourne, Victoria c1949.
- Committee for the Scientific Investigation of Claims of the Paranormal, (CSICOP), a UFO and paranormal skeptics organization, which classifies ufology as a pseudoscience and claims all UFO reports are ultimately explainable as mundane phenomena or hoaxes. CSICOP is the largest and most prominent group of UFO skeptics and debunkers in the United States.
- UFO-Norge, a Norwegian project dedicated to collect all material on observations and physical traces of UFO activity in Norway.
- Erich von Däniken's controversial theories (along with Peter Kolosimo), where he combines what he considers historical proof of extraterrestrial visits with a theory on extraterrestrial help in the evolution of humanity.
- SOBEPS: Société Belge d'Etude des Phénomènes Spatiaux (1971–2007). This group gained fame to have investigated the Belgian Wave (see Black triangle incidents).
- Karla Turner
- Disclosure Project
See Wikipedia: UFO organizations
UFO THEORIES AND EXPLANATIONS
I. Hypotheses involving the objective existence of UFOs
These hypotheses speculate that the phenomena derives wholly or in part from a phenomenon, rather than the mind of the observer.
I.1 The advanced human aircraft hypothesis
This is a theory that all or some UFO sightings are advanced, secret or experimental aircraft of earthly origin. namely that UFOs are military flying saucers; top secret or experimental aircraft unfamiliar to most people.
- During the 1980s, there were reports of "black triangle" UFOs. Some of these were the secret F-117 Nighthawk, which became known to the public in November 1988.
- Nazi Germany is known to have experimented with circular jet planes using the Coanda effect. At least one of the scientists involved was taken to the USA after WWII. Experiments with these designs and their descendants down the years may explain many sightings of circular UFO's.
There is a theory that the secret groups developing these aircraft in the USA, have been encouraging ufology to follow the Extraterrestrial hypothesis line of thought, to cover up for sightings.
The development of disc shaped aircraft — or military "flying saucers" — apparently dates back to World War II. Since most of the information is highly classified, many details are uncertain.
A number of disc-shaped aircraft have been proposed over the years, a few being built. The best documented of these was Arthur Sack's experimental Sack AS-6, a small light plane built just before the start of World War II.
In 1934, at Miami University (of Ohio), an aircraft called the Nemeth Umberallaplane (aka Roundwing) was tested. (Nemeth was sometimes spelled Nuneth). This aircraft had a circular wing on top of the rectangle fuselage, a propellor in front, wheels underneath the fuselage and a rudder with tailfins. There were no wings extending from the middle of the fuselage. The aircraft looked like AWACS plane, except for the missing middle wings. The aircraft is named in the 1976 reference book "Airplanes of the World" as the "Flying Saucer" plane, (the book also mentions the Avro Avrocar, the Vought V-173, and the Vought XF5U. Nemeth article photograph
During the war some research was carried out by a number of designers on circular wings. Led by design-engineer Charles Zimmerman, Chance-Vought led a series of designs that eventually resulted in the Vought Flying Flapjack, perhaps the first aircraft explicitly designed as a disc for aerodynamic reasons. Generally wings with large chord (front to back length) compared to span (side to side length), described by a wing's aspect ratio, have very poor performance due to high induced drag. One way to avoid this problem is to taper the wingtips to a point, which is why the Supermarine Spitfire used an elliptical planform. In the Flapjack this was taken to an extreme, resulting in a plane with a huge wing and very low wing loading, allowing it to take off from aircraft carriers with ease. The Flapjack's engine's were moved to the ends of the wings to further reduce the drag induced by air currents there. By the time the design was flying in the post-war era, jet engines had rendered the design obsolete and the US Navy lost interest.
In 1943, the Boeing Aircraft built 3 scale model aircraft designs that had saucer-shaped wings with a propellor in the front and a tail rudder in the back. The cockpit, (where the pilot sat), was to be in front of the wings. There was no actual fuselage in the center. The aircraft model numbers were 390, 391, and 396. They were to be powered by a Pratt & Whitney R-4360-3 Wasp Major radial engine and capable of reaching speeds of 414mph and intended to be fighter planes, armed with 4 20mm cannons and underwing hardpoints that could carry 2 500 lb. bombs or external fuel tanks. Boeing submitted the proposals to the US Navy. The wing design had excellent Short TakeOff and Landing charteristics, and STOL is preferred for fixed-wing aircraft carrier planes. The Navy rejected the Boeing designs in favor of the similar-shaped Chance-Vought V-173/XF5U-1 aircraft.  
In the US, a number of experimental saucer shaped craft were apparently developed as black projects by Lockheed Corporation for the USAF, and by Convair for the CIA. The saucer had the advantages of being a Vertical take-off and landing design (so avoiding the need for easily damaged runways), while the shape was well suited to diffusing radar and so making the craft stealthy. These early designs were apparently powered by turbojets, which powered a horizontal rotor to provide lift using the Coanda effect.
In an apparent attempt to quell speculation about the military nature of flying saucers, a press conference was held in July 1952, at which Major John A. Sandford denied any knowledge of the craft, and retired Major Donald E. Keyhoe declared his belief that they were of alien origin. In 1957 Keyhoe became head of the civilian UFO group NICAP (National Investigations Committee on Aerial Phenomena.
Meanwhile in Canada, the Avro Canada company was also attempting to develop saucer shaped craft, funded (initially) by the Canadian government. John Frost had initiated the design while experimenting with different ways to build more efficient jet engines, eventually settling on a large disc-shaped device with the exhaust towards the outside. He then wrapped the smallest possible airframe around the engine, piping the exhausts to the rear. For VTOL the aircraft sat on its tail for takeoff and landing, generating lift in forward flight as a large delta wing.
Frost also became interested in the Coanda effect to produce lift, eventually abandoning the original delta wing design and replacing it with a true disc. In this model the exhaust was directed downward around the entire disc by a flap ringing the aircraft, allowing it to take off and land "flat". Once in flight the flap would be angled slightly, producing a small downforce while being directed to the rear. Little lift would be generated by conventional means, the engine exhaust would instead be used to build an "artificial wing" by directing the airflow around the craft. He offered a number of increasingly dramatic performance estimates, generally claiming Mach 4 performance at 80,000 ft (24,000 m), at which point the USAF took over funding under Weapon System 606A. The result was a 29-foot (8.9 m) diameter supersonic Project Y2.
Testing soon revealed that the entire concept was unworkable; the craft would be highly unstable at supersonic speeds. Avro nevertheless continued work on the project as a subsonic design known as Project Silver Bug. Silver Bug was of interest to the US Army, who was looking for solutions for battlefield transport and support, and they took over most of the project funding. The final outcome of Silver Bug was the Avrocar or VZ-9AV, effectively (and unintentionally) a prototype hovercraft rather than an aircraft, which was made public in 1961. After Avro experienced financial difficulties in 1959, funding for future projects was apparently directed to the Bell Aircraft Corporation. Meanwhile the helicopter had proven to be the solution the Army was looking for.
During the 1980s, reports of triangular shaped UFOs revealed the existence of the F-117 Nighthawk—another black project—which became public in November 1988.
The Sikorsky Cypher is a doughnut-shaped, experimental, prototype unmanned vertical takeoff and landing aerial vehicle. The Sikorsky Cypher II, (a.k.a. Sikorsky Mariner), followup aircraft has wings extending from the left and right sides of the aircraft.
See Wikipedia: Military flying saucers
I.2 The extraterrestrial hypothesis
The extraterrestrial hypothesis (ETH) theorizes that some UFO sightings are alien spacecraft. The Extraterrestrial hypothesis (ETH), defined by Edward U. Condon in the 1968 Condon Report as "The idea that some UFOs may be spacecraft sent to Earth from another civilization, or on a planet associated with a more distant star", further attributing the popularity of the idea to Donald Keyhoe's UFO book from 1950 , though the idea clearly predated Keyhoe, appearing in newspapers and various government documents . This is probably the most popular theory among Ufologists.
Origins of the term extraterrestrial hypothesis are unknown. It was used in a publication by French engineer Aimé Michel in 1967 and again by James Harder, while testifying before the Congressional Committee on Science and Astronautics, in July 1968. In 1969, physicist Edward Condon defined ETH as the "idea that some UFOs may be spacecraft sent to Earth from another civilization, or on a planet associated with a more distant star," while presenting the findings of the much debated Condon Report.
Sub-set ETH theories:
The Staging hypothesis
A sub-set of the ETH, the Staging Hypothesis, prevalent up until the 1980s, speculated that extraterrestrials have "stage-managed" encounters as a deliberate policy to "educate" humanity.
The Hostility hypothesis
Wilhelm Reich and Jerome Eden have the hypothesis that UFOs - or at least some of them - or the beings traveling in the UFOs - are hostile. They claim that the waste product of the UFO engines is what they call "Deadly Orgone" (DOR) which ruins the atmosphere, dries it out, and is one cause, if not the most important cause, of the development of deserts. They found this during their operations with the "Cloudbuster".
Eden, just like several other researchers, attributes the Cattle mutilations, cases such as "Snippy the horse", to aliens, and claims that these beings abduct persons, manipulate their feelings and thoughts, cause military aircraft to crash or disappear, but they do not make open contact to government or military. That they even try to "educate" mankind in the way that the human beings develop a spiritual attitude towards aliens and UFOs, hoping that the aliens arrive as the saviors for the big problems of mankind and earth, when, in fact, their agenda involves exploiting Earth's natural resources and destroying its water and atmosphere.
Amateur photographs from Sheffield, England, 4 March 1962 & Minneapolis, Minnesota, 20 October 1960. Taken from a 1997 CIA training manual.
Time travel or parallel worlds
Alternately, UFO's are craft that come from a parallel dimension or similar, or are human-manufactured craft from the future capable of time travel.
The Zoo hypothesis
The zoo hypothesis is one of a number of suggestions that have been advanced in response to the Fermi paradox, regarding the apparent absence of evidence in support of the existence of advanced extraterrestrial life. According to this hypothesis, aliens would generally avoid making their presence known to humanity, or avoid exerting an influence on human development, somewhat akin to zookeepers observing animals in a zoo.
Adherents of the hypothesis consider that Earth and humans are being secretly surveyed using equipment located on Earth or elsewhere in the solar system which relays information back to the observers. It is also suggested that overt contact will eventually be made with humanity once humans reach a certain level of development.
See Wikipedia: Zoo hypothesis
Although ETH, as a unified and named hypothesis, is a comparatively new concept - one which owes a lot to the saucer sightings of the 1940s–1960s - ETH can trace its origins back to a number of earlier iterations such as the now discredited Martian canals promoted by astronomer Percival Lowell, popular culture, including the writings of H. G. Wells and fellow science fiction pioneers, 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.
Historical reports of extraterrestrial visits
An early example of speculation over extraterrestrial visitors can be found in the French newspaper Le Pays. On June 17, 1864, Le Pays published a story about two American geologists who 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.
A further report can be found in the Missouri Democrat (St. Louis), which, in October 1865, reported on the story of Rocky Mountain trapper James Lumley, who claimed to have discovered fragments of rock bearing "curious hieroglyphics" which seemed to form a compartmentalized object; which he believed was being used to transport "an animate being", after investigating a meteor impact near Great Falls, Montana. The newspaper goes on to speculate "Possibly, meteors could be used as a means of conveyance by the inhabitants of other planets, in exploring space".
Credit for popularizing the idea of Martian visitation and invasion probably goes to H. G. Wells in his 1898 science fiction classic War of the Worlds. However, even before Wells, there was a sudden upsurge in reports in "Mystery airships" in the U.S. UFO historians Jerome Clark and David M. Jacobs  note that extraterrestrial visitation, particularly from Mars, was sometimes proposed to explain these mystery airship waves. For example, the Washington ‘’Times’’ in 1897 speculated that the airships were "a reconnoitering party from Mars" and the Saint Louis ‘’Post-Dispatch’’ wrote, "these may be visitors from Mars, fearful, at the last, of invading the planet they have been seeking."  Later there was a more international airship wave from 1909-1912. An example of an extraterrestrial explanation at the time was a 1909 letter to a New Zealand newspaper suggested "atomic powered spaceships from Mars.” 
Starting in the 1920s, 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, Flash Gordon serials have Earth being attacked from space by alien meteors, ray beams, and biological weapons. In 1938, a radio broadcast version of War of the Worlds by Orson Welles, using a modern setting for H. G. Wells’ Martian invasion, created some public panic in the U.S. This would later figure into some commentary on what was happening in 1947 when “flying saucers” finally hit the U.S.
UFOs and ETH
Regarding modern UFO sightings and their link to the ETH, literature professor and skeptic Terry Matheson wrote, "…sightings of unidentifiable lights the sky had been taking place for centuries, but only after Kenneth Arnold’s flying saucer sighting on June 24, 1947, near Mt. Rainier, Washington (see below), were they explicitly theorized to be extraterrestrial in origin." 
The modern ETH - specifically the implicit linking of unidentified aircraft and lights in the sky to alien life - took root during the late 1940s and took its current form during the 1950s. It drew on pseudoscience as well as popular culture. However, unlike earlier speculation of extraterrestrial life, interest in the ETH was also bolstered by many unexplained sightings investigated by government and private civilian groups, such as NICAP and APRO.
The 1947 U.S. flying saucer wave
On June 24, 1947, at about 3.00 p.m. local time, pilot Kenneth Arnold reported seeing nine unidentified disk-shaped aircraft flying near Mt. Rainier.  
Arnold said the objects moved as if they were a saucer skipping across water, but also described the shape as thin, flat, and disc-like or saucer-like (also like a "pie-plate," "pie-pan," and "half-moon shaped")--see Kenneth Arnold article for detailed quotes. Three days later, the terms "flying disc" and "flying saucer" first appeared in newspapers and became the preferred terms for the phenomenon for a number of years, until largely replaced in the 1950s and 1960s by UFO.
Though he was impressed by their high speed and quick movements, Arnold did not initially consider the ETH, stating,
"I assumed at the time they were a new formation or a new type of jet, though I was baffled by the fact that they did not have any tails. They passed almost directly in front of me, but at a distance of about 23 miles, which is not very great in the air. I judged their wingspan to be at least 100 feet across. Their flying did not particularly disturb me at the time, except that I had never seen planes of that type."
However, when no aircraft emerged that seemed to account for what he had seen, Arnold clearly did consider the possibility of the objects being extraterrestrial. In the same 1950 interview with journalist Edward R. Murrow Arnold added, "...if it's not made by our science or our Army Air Forces, I am inclined to believe it's of an extraterrestrial origin." 
When the flying saucer wave hit the U.S., even if people thought the saucers were real, they were generally unwilling to leap to the conclusion that they were extraterrestrial in origin. Various theories began to quickly proliferate in press articles, such as secret military projects, Russian spy devices, hoaxes, and mass hysteria, but the ETH was not generally among them. According to Murrow, the ETH as an explanation for "flying saucers" did not earn widespread attention until about 18 months after Arnold's sighting.
These attitudes seem to be reflected in the results of the first US poll of public UFO perceptions released by Gallup on August 14, 1947. The term "flying saucer" was familiar to 90% of the respondents. It further showed that most people either held no opinion (33%), or believed that there was a mundane explanation for apparent UFOs. 29% thought they were an optical illusion, 15% a US secret weapon, 10% a hoax, 3% a “weather forecasting device”, 1% of Soviet origin, and 9% had “other explanations”, including fulfillment of Biblical prophecy, secret commercial aircraft, or related to atomic testing.
On July 10, U.S. 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.” On July 8, Dewitt Miller was quoted by UP saying that the saucers had been seen since the early nineteenth century. 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.”  At the same time, several nationally syndicated columns by humorist Hal Boyle spoke of a green man from Mars in his flying saucer (see Little green men).
Even Arnold commented along these lines. In a June 28 article, he described an encounter he had with a near-hysterical woman in Pendleton, Oregon, shrieking, "there's the man who saw the men from Mars." Arnold then added, "This whole thing has gotten out of hand... Half the people I see look at me as a combination Einstein, Flash Gordon and screwball." 
Military investigations begin: ETH conclusion and debunkery
On July 9, Army Air Force Intelligence began a secret study of the best saucer reports, including Arnold's. A follow-up study by the Air Materiel Command intelligence and engineering departments at Wright Field Ohio led to the formation the U.S. Air Force's Project Sign at the end of 1947, the first official U.S. military UFO study.
In the summer of 1948, Project Sign wrote their Estimate of the Situation, which concluded that the remaining unidentified sightings were best explained by the ETH. However, the report ultimately was rejected by the USAF Chief of Staff, General Hoyt Vandenberg, citing a lack of physical evidence, and its existence was not publicly disclosed until 1956 by later Project Blue Book director Edward J. Ruppelt. Ruppelt also indicated that Vandenberg dismantled Project Sign after they wrote their ETH conclusion.
With this official policy in place, all subsequent public Air Force reports concluded that there was either insufficient evidence to link UFOs and ETH, or that UFOs did not warrant investigation.
Immediately following the great UFO wave of 1952 and military debunkery of the radar and visual sightings plus jet interceptions over Washington, D.C. in August, the CIA’s Office of Scientific Investigation took particularly interest in UFOs. Though the ETH was mentioned, it was generally given little credence. However, others within the CIA, such as the Psychological Strategy Board, were more concerned about how an unfriendly power such as the Soviet Union might use UFOs for psychological warfare purposes, exploit the gullibility of the public for the sensational, and clog intelligence channels. Under a directive from the National Security Council to review the problem, in January 1953, the CIA organized the Robertson Panel , a group of scientists who quickly reviewed the Blue Book’s best evidence, including motion pictures and an engineering report that concluded that the performance characteristics were beyond that of earthly craft. After only two days review, all cases were claimed to have conventional explanations. An official policy of public debunkery was recommended using the mass media and authority figures in order to influence public opinion and reduce the number of UFO reports.
Evolution of public opinion
The early 1950s also saw a number of movies depicting flying saucers and aliens, including The Day the Earth Stood Still (1951), The War of the Worlds, Earth vs. the Flying Saucers (1956), and Forbidden Planet (1956).
Despite this, public belief in ETH seems to have remained low during the early 1950s, even among those reporting UFOs. A poll published in Popular Mechanics magazine, in August 1951, showed that 52% of UFO witnesses questioned believed that they had seen a man-made aircraft, while only 4% believed that they had seen an alien craft. However, within a few years, belief in ETH had increased due to the activities of people such as retired U.S. Marine Corp officer Maj. Donald E. Keyhoe, who campaigned to raise public awareness of the UFO phenomena. By 1957, 25% of Americans responded that they either believed, or were willing to believe, in ETH, while 53% responded that they weren't (though a majority of these respondents indicated they thought UFOs to be real but of earthly origin). 22% said that they were uncertain.  
During this time, the ETH also fragmented into distinct camps, each believing slightly different variations of the hypothesis. The "contactees" of the early 1950s said that the "space brothers" they met were peaceful and benevolent, but by the mid-1960s, a number of alleged Alien abductions; including that of Betty and Barney Hill, and of the apparent mutilation of cattle cast the ETH in more sinister terms.
Opinion polls indicate that public belief in the ETH has continued to rise since then. For example, a 1997 Gallup poll of the U.S. public indicated that 87% knew about UFOs, 48% believed them to be real (vs. 33% who thought them to be imaginary), and 45% believed they had visited Earth.  Similarly a Roper poll from 2002 found 56% thought UFOs to be real and 48% thought they had visited Earth. 
Polls also indicate that the public believes even more strongly that the government is suppressing evidence about UFOs. For example, in both the cited Gallup and Roper polls, the figure was about 70%.
In a 1969 lecture U.S. astrophysicist Carl Sagan said:
"The idea of benign or hostile space aliens from other planets visiting the earth [is clearly] an emotional idea. There are two sorts of self-deception here: either accepting the idea of extraterrestrial visitation by space aliens in the face of very meager evidence because we want it to be true; or rejecting such an idea out of hand, in the absence of sufficient evidence, because we don't want it to be true. Each of these extremes is a serious impediment to the study of UFOs.".
Similarly, British astrophysicist Peter A. Sturrock wrote that for many years,
"Discussions of the UFO issue have remained narrowly polarized between advocates and adversaries of a single theory, namely the extraterrestrial hypothesis ... this fixation on the ETH has narrowed and impoverished the debate, precluding an examination of other possible theories for the phenomenon."
Opinions among scientists
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.
A cited example of this was an informal poll conducted in 1977 by astrophysicist Peter A. Sturrock, surveying the members of the American Astronomical Society. Sturrock asked polled scientists to assign probabilities to eight possible explanations for UFOs. The results were: 
||An unfamiliar natural phenomenon
||A familiar phenomenon or device
||An unfamiliar terrestrial device
||An unknown natural phenomenon
||Some specifiable other cause
||An alien device
||Some unspecified other cause
An earlier poll done by Sturrock in 1973 of American Institute of Aeronautics and Astronautics members found that a somewhat higher 10% believed UFOs were vehicles from outer space.
The primary scientific arguments against ETH were summarized by Astronomer and UFO researcher J. Allen Hynek during a presentation at the 1983 MUFON Symposium. During which time he outlined seven key reasons why he could not accept the ETH. 
- "Failure of Sophisticated Surveillance Systems to Detect Incoming or Outgoing UFOs"
- "Gravitational and Atmospheric Considerations"
- "Statistical Considerations"
- "Elusive, Evasive and Absurd Behavior of UFOs and Their Occupants"
- "Isolation of the UFO Phenomenon in Time and Space: The Cheshire Cat Effect"
- "The Space Unworthiness of UFOs"
- "The Problem of Astronomical Distances"
Hynek argued that:
- Despite worldwide radar systems and Earth-orbiting satellites, UFOs are alleged to flit in and out of the atmosphere, leaving little to no evidence.
- Space aliens are alleged to be overwhelmingly humanoid, and are allegedly able to exist on Earth without much difficulty (often lacking "space suits", despite the fact that extra-solar planets would likely have different atmospheres, biospheres, gravityand other factors, and extraterrestrial life would likely be very different from Earthly life.)
- The number of reported UFOs and of purported encounters with UFO-inhabitants outstrips the number of expeditions that an alien civilization (or civilizations) could statistically be expected to mount.
- The behavior of extraterrestrials reported during alleged abductions is often inconsistent and irrational.
- UFOs are isolated in time and space: like the Cheshire Cat, they seem to appear and disappear at will, leaving only vague, ambiguous and mocking evidence of their presence
- Reported UFOs are often far too small to support a crew traveling through space, and their reported flight behavior is often not representative of a craft under intelligent control (erratic flight patterns, sudden course changes).
- The distance between planets makes interstellar travel impractical, particularly because of the amount of energy that would be required for interstellar travel using conventional means, (According to a NASA estimate, it would take 7 × 1019 Joules of energy to send the current space shuttle on a one-way, 50 year, journey to the nearest star, an enormous amount of energy ) and because of the level of technology that would be required to circumvent conventional energy/fuel/speed limitations using exotic means suchs as Einstein Rosen Bridges as ways to shortened distances from point A to point B.(see Faster than light travel). 
According to Hynek, points 1 through 6 could be argued, but point 7 represented an insurmountable barrier to the validity of the ETH. 
More recently, Professor Stephen Hawking argued that because most UFOs turn out to have prosaic explanations, it was reasonable to presume that the "unidentified" UFOs also had prosaic origins. 
Physicist Bernard Haisch on his "ufoskeptic" website  presents a number of counterarguments to those of Hynek. Haisch argues he is convinced something is going on and that modern theories of physics and cosmology might support extraterrestrial or even interdimensional origins for UFOs.
In a 1969 report to the American Association for the Advancement of Science, the late American physicist James E. McDonald summarized his reasons for not dismissing ETH:
"Present evidence surely does not amount to incontrovertible proof of the extraterrestrial hypothesis. What I find scientifically dismaying is that, while a large body of UFO evidence now seems to point in no other direction than the extraterrestrial hypothesis, the profoundly important implications of that possibility are going unconsidered by the scientific community because this entire problem has been imputed to be little more than a nonsense matter unworthy of serious scientific attention." 
NASA frequently fields questions in regard to the ETH and UFOs. As of 2006, its official standpoint was that ETH has a lack of empirical evidence.
"No one has ever found a single artifact, or any other convincing evidence for such alien visits". David Morrison.  "As far as I know, no claims of UFOs as being alien craft have any validity -- the claims are without substance, and certainly not proved". David Morrison 
Despite public interest, NASA considers the study of ETH to be irrelevant to its work because of the number of false leads that a study would provide, and the limited amount of usable scientific data that it would yield.
"That whole subject is really irrelevant to our own human quest to travel to space ... if someone in the previous century saw a film of a 747 flying past, it would not tell them how to build a jet engine, what fuel to use, or what materials to make it out of. Yes, the wings are a clue, but just that, a clue." NASA. 
Documents and investigations regarding the Extraterrestrial Hypothesis
Other private or governmental studies, some secret, have concluded in favor of the Extraterrestrial hypothesis (ETH), or have had members who disagreed with official conclusions against the conclusion by committees and agencies to which they belonged. The following are examples of sources that have focused specifically on the topic:
- In 1967, Greek physicist Paul Santorini, a Manhattan Project scientist, publicly stated that a 1947 Greek government investigation that he headed into the European Ghost rockets of 1946 quickly concluded that they were not missiles. Santorini claimed the investigation was then quashed by military officials from the U.S., who knew them to be extraterrestrial, because there was no defense against the advanced technology and they feared widespread panic should the results become public. 
- A 1948 Top Secret USAF Europe document (at right) states that Swedish air intelligence informed them that at least some of their investigators into the ghost rockets and flying saucers concluded they had extraterrestrial origins: "...Flying saucers have been reported by so many sources and from such a variety of places that we are convinced that they cannot be disregarded and must be explained on some basis which is perhaps slightly beyond the scope of our present intelligence thinking. When officers of this Directorate recently visited the Swedish Air Intelligence Service... their answer was that some reliable and fully technically qualified people have reached the conclusion that 'these phenomena are obviously the result of a high technical skill which cannot be credited to any presently known culture on earth.' They are therefore assuming that these objects originate from some previously unknown or unidentified technology, possibly outside the earth."
- West Germany, in conjunction with other European countries, conducted a secret study from 1951 to 1954, also concluding that UFOs were extraterrestrial. This study was revealed by German rocketry pioneer Hermann Oberth, who headed the study and who also made many public statements supporting the ETH in succeeding years. At the study's conclusion in 1954, Oberth declared, "These objects (UFOs) are conceived and directed by intelligent beings of a very high order. They do not originate in our solar system, perhaps not in our galaxy." Soon afterwards, in an article in The American Weekly, October 24, 1954, Oberth wrote "It is my thesis that flying saucers are real and that they are space ships from another solar system. I think that they possibly are manned by intelligent observers who are members of a race that may have been investigating our earth for centuries..." 
- During the height of the flying saucer "flap" of July 1952, including highly publicized radar/visual and jet intercepts over Washington, D.C., the FBI was informed by the Air Force Directorate of Intelligence that they thought the "flying saucers" were either "optical illusions or atmospheric phenomena" but then added that, "some Military officials are seriously considering the possibility of interplanetary ships." 
- The CIA started their own internal scientific review the following day. Some CIA scientists were also seriously considering the ETH. An early memo from August was very skeptical, but also added, "...as long as a series of reports remains 'unexplainable' (interplanetary aspects and alien origin not being thoroughly excluded from consideration) caution requires that intelligence continue coverage of the subject." A report from later that month was similarly skeptical but nevertheless concluded "...sightings of UFOs reported at Los Alamos and Oak Ridge, at a time when the background radiation count had risen inexplicably. Here we run out of even 'blue yonder' explanations that might be tenable, and we still are left with numbers of incredible reports from credible observers." A December 1952 memo from the Assistant CIA Director of Scientific Intelligence (O/SI) was much more urgent: "...the reports of incidents convince us that there is something going on that must have immediate attention. Sightings of unexplained objects at great altitudes and traveling at highs speeds in the vicinity of U.S. defense installation are of such nature that they are not attributable to natural phenomena or known types of aerial vehicles." Some of the memos also made it clear that CIA interest in the subject was not to be made public, partly in fear of possible public panic. (Good, 331–335)
- The CIA organized the January 1953 Robertson Panel of scientists to debunk the data collected by the Air Force's Project Blue Book. This included an engineering analysis of UFO maneuvers by Blue Book (including a motion picture film analysis by Naval scientists) that had concluded UFOs were under intelligent control and likely extraterrestrial.
- Extraterrestrial "believers" within Project Blue Book included Major Dewey Fournet, in charge of the engineering analysis of UFO motion, who later became a board member on the civilian UFO organization NICAP. Blue Book director Edward J. Ruppelt privately commented on other firm "pro-UFO" members in the USAF investigations, including some Pentagon generals, such as Charles P. Cabell, USAF Chief of Air Intelligence, who angry at the inaction and debunkery of Project Grudge, dissolved it in 1951, established Project Blue Book in its place, and made Ruppelt director.  In 1953, Cabell became deputy director of the CIA. Another defector from the official Air Force party line was consultant Dr. J. Allen Hynek, who started out as a staunch skeptic. After 20 years of investigation, he changed positions and generally supported the ETH. He became the most publicly known UFO advocate scientist in the 1970s and 1980s.
- The first CIA Director, Vice Admiral Roscoe H. Hillenkoetter, stated in a signed statement to Congress, also reported in the New York Times, February 28, 1960, "It is time for the truth to be brought out... Behind the scenes high-ranking Air Force officers are soberly concerned about the UFOs. However, through official secrecy and ridicule, many citizens are led to believe the unknown flying objects are nonsense... I urge immediate Congressional action to reduce the dangers from secrecy about unidentified flying objects." In 1962, in his letter of resignation from NICAP, he told director Donald Keyhoe, "I know the UFOs are not U.S. or Soviet devices. All we can do now is wait for some actions by the UFOs."
- Although the 1968 Condon Report came to a negative conclusion (written by Condon), it is known that many members of the study strongly disagreed with Condon's methods and biases. Most quit the project in disgust or were fired for insubordination. A few became ETH supporters. Perhaps the best known example is Dr. David Saunders, who in his 1968 book UFOs? Yes lambasted Condon for extreme bias and ignoring or misrepresenting critical evidence. Saunders wrote, "It is clear... that the sightings have been going on for too long to explain in terms of straightforward terrestrial intelligence. It's in this sense that ETI (Extra Terrestrial Intelligence) stands as the 'least implausible' explanation of 'real UFOs'." 
- In 1999, the private French COMETA report (written primarily by military defense analysts) stated the conclusion regarding UFO phenomena, that a "single hypothesis sufficiently takes into account the facts and, for the most part, only calls for present-day science. It is the hypothesis of extraterrestrial visitors." [Read the COMETA report] The report noted issues with formulating the extraterrestrial hypothesis, likening its study to the study of meteorites, but concluded that although it was far from the best scientific hypothesis, "strong presumptions exist in its favour". The report also concludes that the studies it presents "demonstrate the almost certain physical reality of completely unknown flying objects with remarkable flight performances and noiselessness, apparently operated by intelligent [beings] … Secret craft definitely of early origins (drones, stealth aircraft, etc.) can only explain a minority of cases. If we go back far enough in time, we clearly perceive the limits of this explanation."
- Jean-Jacques Velasco, the head of the official French UFO investigation SEPRA, wrote a book in 2005 saying that 14% of the 5800 cases studied by SEPRA were utterly inexplicable and extraterrestrial in origin.  Yves Sillard, the head of the new official French UFO investigation GEIPAN and former head of the French space agency CNES, echoes Velasco's comments and adds the U.S. is guilty of covering up this information.  Again, this isn't the official public posture of SEPRA, CNES, or the French government. (CNES recently placed their 5800 case files on the Internet starting March 2007.)
November 1948 USAF Top Secret document citing extraterrestrial opinion
1952 USAF Top Secret document citing
The 1967 Falcon Lake incidentreport filed by the Royal Canadian Mounted Police on Stephen Michalak claimed incident with a UFO.
I.3 The extraterrestrial energyzoa hypothesis
The » extraterrestrial energyzoa hypothesis (ETZH) is and alternative hypothesis of the extraterrestrial hypothesis, that some of the UFO phenomena is best explained as being some kind of biological lifeforms and not creatures from other planets occupying physical spacecraft visiting Earth. The issue has already been a matter of discussion in astrobilological
speculation known as the atmospheric beast hypothesis.
The extraterrestrial energyzoa hypothesis can be dated back to Trevor James Constable's » "Sky Critter Theory", which is perhaps one of the strangest theories advanced as an explanation for the UFO phenomenon. » Trevor James Constable was one of the proponents of the theory, claiming that UFO's came from a parallel universe known as Etheria and that there were two categories of UFO, some were machines and others living creatures. These invisible creatures he called "Sky Critters" and that they live in the atmosphere. The theory speculated that UFO sightings involve the sighting of exotic unknown life otherwise known as "Critters" or "Heat Critters" . This theory seems to have some connections to Constable's interpretations on Wilhelm Reich's Orgone energy .
The hypothesis relating certain kind of UFO phenomenon to biological hydrozoa behavior was first formulated by » Daniel Tarr in 2006. He coined the term "energyzoa".
I.4 The Interdimensional hypothesis
The Interdimensional hypothesis (IDH or IH — also called the extradimensional hypothesis or EDH) is a theory advanced by Jacques Vallée that unidentified flying objects (UFOs) and related events involve visitations from other "realities" or "dimensions" coexisting separately alongside our own. It is an alternative to the extraterrestrial hypothesis (ETH).
IDH also holds that UFOs are a modern manifestation of a phenomenon that has occurred throughout recorded human history, which in prior ages were ascribed to mythological or supernatural creatures.
Strictly, IDH is considered a belief system rather than a hypothesis like ETH, because it is not falsifiable through scientific testing and experiment. Verification of IDH requires interdimensional observation techniques, which are themselves scientifically unverified. IDH is evaluated by UFOlogists solely on the basis of how well it fits.
Although ETH has remained the predominant explanation for UFOs by UFOlogists, some UFOlogists have abandoned it in favor of IDH. Paranormal researcher Brad Steiger wrote that "we are dealing with a multidimensional paraphysical phenomenon that is largely indigenous to planet Earth". Other UFOlogists, such as John Ankerberg and John Weldon, advocate IDH because is fits the explanation of UFOs as a spiritistic phenomenon. Commenting on the disparity between the ETH and the accounts that people have made of UFO encounters, Ankerberg and Weldon wrote "the UFO phenomenon simply does not behave like extraterrestrial visitors."
The development of IDH as an alternative to ETH increased in the 1970s and 1980s with the publication of books by Vallée and J. Allen Hynek. In 1979, Vallée and Hynek advocated the hypothesis in The Edge of Reality: A Progress Report on Unidentified Flying Objects and further, in Vallée's 1980 book Messengers of Deception: UFO Contacts and Cults. 
Some UFO proponents accepted IDH because nobody had demonstrated an anti-gravity or speed-of-light travel hypothesis that could explain extraterrestrial machines. With IDH, it is unnecessary to explain any propulsion method because the IDH holds that UFOs are not spacecraft, but rather devices that travel between different realities.
IDH has been a causative factor in establishing UFO religion. 
I.5 The Cosmic Trickster and Ultraterrestrial hypothesis
Endorsed by John Keel (who coined the term "ultraterrestrial"), Jacques Vallée in his Passport to Magonia, Robert Anton Wilson and Terence McKenna, this theory claims that UFO's have an objective reality, though of a kind humans cannot comprehend or understand.
A frequent sub-set of this theory conjectures that in the past the ultimate reality behind UFO's manifested as angels, demons, fairies and other "supernatural" beings. This over-laps both with the Staging Hypothesis and the Psychosocial Hypothesis.
I.6 UFO's as supernatural beings
Paranormal and occult hypotheses about UFOs refers to the hypotheses that the unidentified flying objects are related to or caused by the paranormal or occult. There has been a fair amount of crossover between people's interest in paranormal events and unidentified flying objects. The study of both is generally seen as pseudoscience by mainstream science and presently finds no support in scientific literature.
Mystics, extraterrestrials and contactees
In his 1758 book Earths in the Solar World, Emanuel Swedenborg reported a number of visions where he was escorted around various planets. He regarded these visions as genuine.
Among Madame Blavatsky’s writings were her descriptions of “The Lords of the Flame”, who resided on Venus. Guy Ballard - one of Blavatsky's disciples - popularised her teachings in the United States. He founded an offshoot, “The Great I AM”, which made contact with extraterrestrials a vital part of its teachings.
Though early contactees spoke of extraterrestrial contact, but the general tone and the sort of messages imparted by extraterrestrials seemed almost interchangeable, in many accounts, as those offered by mediums and mystics. As early as the 17th century, the polymath John Dee and his assistant Edward Kelley, working together, communed with superior and unearthly beings (which he called angels) who imparted to them a strange language, Enochian, and imparting to them "wisdom" and knowledge.
Heavily inspired by the writings of H. P. Lovecraft, the Left Hand Path occultists Kenneth Grant and Michael Bertiaux have formed magical orders devoted to using tantric and ceremonial magic as a means to contact extraterrestrial (and/or extradimensional) entities.
Theorists and popularizers
Carl Jung, the famous psychologist, also theorized that UFOs might have a primarily spiritual and psychological basis. In his 1959 book "Flying Saucers: A Modern Myth of Things Seen In The Sky", he pointed out that the round shape of most saucers corresponds to a mandala, a type of archetypal shape seen in religious images. Thus the saucers might reflect a projection of the internal desires of viewers to see them. However, he did not label them as delusions or hallucinations outright; it was more in the nature of a shared spiritual experience. However, Jung seemed conflicted as to possible origins. At other times he asserted that he wasn't concerned with possible psychological origins and that at least some UFOs were physically real, based primarily on indirect physical evidence such as photographs and radar contact in addition to visual sightings. He also considered the extraterrestrial hypothesis to be viable. In 1958 the AP quoted him as saying, "A purely psychological explanation is ruled out.... If the extraterrestrial origin of these phenomena should be confirmed, this would prove the existence of an intelligent interplanetary relationship.... That the construction of these machines proves a scientific technique immensely superior to ours cannot be disputed."
John Keel and Brad Steiger promulgated various paranormal/UFO theories in a series of paperback books in the 1960s and 1970s. Keel in particular speculated that UFOs might have their origins not in space and time as we know it, but outside of it. He advocated that we may not do well to trust superior beings but to regard them as quite often deceptive or manipulative if not parasitic. Dr. Jacques Vallée, a French ufologist, noted an almost exact parallel between UFO and "Alien" visitations and stories from folklore of Fairies and similar creatures. This was documented in his 1969 book "Passport to Magonia" and explored further in his later works. The significance of these parallels is disputed between mainstream scientists, who contend that both are fanciful, and Vallée and others who feel that some underlying poorly understood phenomenon is actually interacting with humans to cause both kinds of sightings. Terence McKenna, in contrast, believed that UFOs are manifestations of the human soul, or collective spirit. He thought they appeared to individuals and groups in order to exert psychological influence over the course of history and might preside, in the year 2012, over history's end.
In the 1980s, this point of view had formalized into a paradigm in and of itself. Researcher Hilary Evans published two well-researched studies, Gods, Spirits, Cosmic Guardians: Encounters with Non-Human Beings and Visions, Apparitions, Alien Visitors: A Complete Study of the Entity Enigma trying to examine phenomena ranging from "ghosts" to "aliens" using similar principles, seeming to conclude that entities may have originated in the minds of the experiencers, with paranormal components. Since that time, discussion has stalled, with no one having much of substance to offer; writing tends to consist of repetitions of old theories [original research?].
The U.S. Government Printing Office issued a publication compiled by the Library of Congress for the Air Force Office of Scientific Research: "UFOs and Related Subjects: An Annotated Bibliography". In preparing this work, the senior bibliographer, Lynn E. Catoe, read thousands of UFO articles and books. In her preface to this 400-page book she states:
A large part of the available UFO literature is closely linked with mysticism and the metaphysical. It deals with subjects like mental telepathy, automatic writing and invisible entities as well as phenomena like poltergeist (ghost) manifestations and possession. Many of the UFO reports now being published in the popular press recount alleged incidents that are strikingly similar to demonic possession and psychic phenomena.
UFOs and mainstream religions
An example of this overlap is the miracle at Fátima which occurred in Portugal in 1917. This involved over 70,000 witnesses observing strange aerial phenomena, which might well be considered as UFOs today.
A few Protestant fundamentalists regard UFOs as inherently demonic and part of a Satanic plan to undermine Christianity, which may involve the supernatural Nephilim as pilots of the UFOs. (See: Article on Christian view on UFOs)
Similar views are held by some [Christian Orthodox] priests and believers, with direct references to affirmations made by saints of the Orthodox Church.   see also  The UFO phenomenon is connected to the arrival of the Antichrist and the wonders he would make to fool the world into believing him, including great fire coming down from the sky. The sky is seen as the place where demons live (see the similarity with Beelzebub - "the lord of the flies", sometimes interpreted as "the lord of the fliers" - i.e. of those who fly). Many similarities can be drawn between UFOs and demonic manifestations: both involve revealing half truths, double truths or deceit, both tend to have a volatile character, as they seem to appear unexpectedly and have an indefinite or illusory character, inducing a sense of wondering and awe, and, more subtly, exposure to or knowledge of both, as incomplete as it is, can induce some abnormal or even pathologic states to those exposed - anxiety, fear, obsession with the phenomenon, and even paranoid schizophrenia, demonomania and suicide, according to John Keel's book "UFOs: Operation Trojan Horse", cited in the links above.
See Wikipedia: Paranormal and Occult Hypotheses About UFOs and UFO religions
I.7 Ancient astronaut theories
Ancient astronaut theories or paleocontact are various proposals that intelligent extraterrestrial beings (called ancient astronauts or ancient aliens) have visited Earth and that this contact is linked to the origins or development of human cultures, technologies, and/or religions.
Some of these theories suggest that deities from most—if not all—religions are actually extraterrestrials, and their technologies were taken as evidence of their divine status.
Ancient astronaut theories have not received support within the scientific community, and have garnered little—if any—attention in peer-reviewed studies from scientific journals. These theories have been popularized, particularly in the latter half of the 20th century, by writers Erich von Däniken, Zecharia Sitchin and Robert K.G. Temple.
Ancient astronaut theories have been widely used in science fiction.
Ancient astronaut adherents often claim that humans are either descendants or creations of beings who landed on Earth millennia ago. An associated theory is that much of human knowledge, religion and culture came from extraterrestrial visitors in ancient times, in that ancient astronauts acted as a “mother culture”. These ideas are generally discounted by the scientific community.
Ancient astronaut theories also may include the idea that civilization may have evolved on Earth twice, and that the visitation of ancient astronauts may reflect the return of descendants of ancient humans whose population was separated from earthbound humans.
Proponents of ancient astronaut theories point to what they perceive as gaps in historical and archaeological records, and to what they see as absent or incomplete explanations of historical or archaeological data. Ancient astronaut proponents cite evidence that they argue supports their assertions, notably, archaeological artifacts that they argue are anachronistic or beyond the presumed technical capabilities of the historical cultures with which they are associated (sometimes referred to as "Out-of-place artifacts"); and artwork and legends which are interpreted as depicting extraterrestrial contact or technologies.
Scientists maintain that gaps in contemporary knowledge of the past do not demonstrate that such speculative ancient astronaut ideas are a necessary, or even plausible, conclusion to draw. The scientific community remains generally skeptical, and the dominant view is that there is no evidence to support ancient astronaut and paleocontact theories.
In their 1966 book Intelligent Life in the Universe  astrophysicists I.S. Shklovski and Carl Sagan devote a chapter  to arguments that scientists and historians should seriously consider the possibility that extraterrestrial contact occurred during recorded history. However, Shklovsky and Sagan stressed that their ideas were speculative and unproven.
Shklovski and Sagan argued that sub-lightspeed interstellar travel by extraterrestrial life was a certainty when considering technologies that were established or feasible in the late '60s; that repeated instances of extraterrestrial visitation to Earth were plausible; and that pre-scientific narratives can offer a potentially reliable means of describing contact with outsiders. 
Additionally, Shklovski and Sagan cited tales of Oannes, a fishlike being attributed with teaching agriculture, mathematics and the arts to early Sumerians, as deserving closer scrutiny as a possible instance of paleocontact due to its consistency and detail.
In his 1979 book Broca's Brain, Sagan suggested that he and Shklovski might have inspired the wave of '70s ancient astronaut books, expressing disapproval of "von Daniken and other uncritical writers" who seemingly built on these ideas not as guarded speculations but as "valid evidence of extraterrestrial contact." Sagan argued that while many legends, artifacts and purported OOPARTs were cited in support of ancient astronaut theories, "very few require more than passing mention" and could be easily explained with more conventional theories. Sagan also reiterated his earlier conclusion that extraterrestrial visits to Earth were possible but unproven, and perhaps improbable.
Evidence cited by proponents
Proponents cite ancient mythologies to support their viewpoints based on the idea that ancient creation myths of gods who descend from the heavens to Earth to create or instruct humanity are actually representations of alien visitors, whose superior technology accounts for their reception as gods. Proponents attempt to draw an analogy to occurrences in modern times when isolated cultures are exposed to Western technology, such as when, in the early 20th century, "cargo cults" were discovered in the South Pacific: cultures who believed various Western ships and their cargo to be sent from the Gods as fulfillment of prophecies concerning their return.
Flying machines are sometimes mentioned in ancient texts; one example is the Vimanas, flying machines found in the Sanskrit epics of India. These tales range from fantastic aerial battles employing various weaponry, to the mundane relating simple technical information, flight procedure, and flights of fancy. (See also Vaimanika Shastra, a text on Vimanas supposedly "channeled" in the early 20th century.) 
In the Biblical Old Testament, the Book of Ezekiel tells of a flying object seen as a fiery whirlwind which when descended to the ground gave the appearance of being made of metal. It is described among other things as a wheel within a wheel containing four occupants, "living creatures", whose likeness was that of man. The passage goes on to say that wherever the wheels went the creatures went, and when the living creatures were lifted up the wheels were lifted up.  The book of Genesis(6:1-4) also tells us of such an encounter where the "sons of heaven" had intercourse with the "daughters of man" which produced the Nephilim.  The apocryphal Book of Enoch tells of similar flying objects and beings called "the Watchers" who have mutinied from "heaven" and descended to earth, but goes further in that Enoch is taken on journeys to various corners of the Earth in the object and at one point even travels to the heavens.  In several chapters of the Old Testament God is depicted as traveling as a column of smoke and/or fire  and making the sound of a trumpet.  These descriptions also describe Yahweh as having a physical presence,  rather than an abstraction. Yahweh is described raining lightning  and stones  down upon the enemies of the Hebrews. However, descriptions of the Hebrew God have also featured protecting wings and outstretched arms in the Psalms, features which may be considered contrary to theories of mechanical manifestations of God. 
Additionally, the characteristics of the Ark of the Covenant and the Urim and Thummim are identified as suggesting high technology, perhaps from alien origins.
Artifacts and artwork
Alleged physical evidence includes the discovery of artifacts in Egypt (the Saqqara Bird) and Colombia-Ecuador, which are claimed to be similar to modern planes and gliders, although these have been interpreted by archaeologists as stylized representations of birds and insects.
More support of this theory draws upon what are claimed to be representations of flying saucers in medieval and renaissance art. This is used to support the ancient astronaut theory by attempting to show that the creators of humanity return to check up on their creation throughout time.
Other artistic support for the ancient astronaut theory has been sought in Palaeolithic cave paintings. Vondijina in Australia and Val Camonica in Italy (seen above) are claimed to bear a resemblance to present day astronauts.Supporters of the ancient astronaut theory sometimes claim that similarities such as dome shaped heads, interpreted as beings wearing space helmets, prove that early man was visited by an extraterrestrial race. 
The ancient Nazca lines comprise hundreds of enormous ground drawings etched into the high desert landscape of Peru, which consist primarily of geometric shapes, but also include depictions of a variety of animals and at least one human figure. Many believers in ancient astronauts cite the Nazca lines as evidence because the figures created by the lines are most clearly depicted or only able to be seen when viewed from the air. Writing professor Joe Nickell of the University of Kentucky, using only technology he believed to be available to people of the time, was able to recreate one of the larger figures with a reasonable degree of accuracy 
Evidence for ancient astronauts is claimed to include the existence of ancient monuments and megalithic ruins such as the Giza pyramids of Egypt, Machu Picchu in Peru, or Baalbek in Lebanon, and the Moai of Easter Island. Supporters contend these stone structures could not have been built with the technical abilities and tools of the people of the time and further argue that many could not be duplicated even today. They suggest that the large size of the building stones, the precision in which they were laid, and the distances many were transported leaves the question open as to who constructed these sites. These contentions are categorically rejected by mainstream archeology. Some mainstream archeologist have participated in experiments to move large megaliths. These experiments have succeeded in moving megaliths up to at least 40 tons,   and they have speculated that with a larger workforce that larger megaliths could be towed with ancient technology.  Such allegations are not unique in history, however, as similar reasoning lay behind the wonder of the Cyclopean masonry walling at Mycenaean cities in the eyes of Greeks of the following "Dark Age," who believed that the giant Cyclopes had built the walls.
Other than the proponents' own interpretations of ancient writings and artifacts, there has yet to be found any hard evidence to support the ancient astronaut hypothesis.
Alan F. Alford, author of Gods of the New Millennium, (1996) was an adherent of the ancient astronaut theory. Much of his work draws on Sitchin’s theories. However, he now finds fault with Sitchin’s theory after deeper analysis, stating that: “I am now firmly of the opinion that these gods personified the falling sky; in other words, the descent of the gods was a poetic rendition of the cataclysm myth which stood at the heart of ancient Near Eastern religions.”
See Wikipedia: Ancient astronaut theories (paleoaustronautics)
Xenoarchaeology is a hypothetical form of archaeology concerned with the physical remains of past (but not necessarily extinct) alien cultures. These may be found on planets or satellites, in space, the asteroid belt, planetary orbit or Lagrangian points.
Xenoarchaeology is currently only hypothetical science that exists mainly in science fiction works and is not practiced by mainstream archaeologists. Although some fringe theories of alien archaeology exist, and several attempts at observing extraterrestrial structures at common Lagrangian points in our solar system have been made, most serious archaeological work has been in refutation of it.
See Wikipedia: Xenoarchaeology
I.8 Conspiracy theories
A UFO conspiracy theory is any one of many often overlapping conspiracy theories which argue that the government is said to be intentionally covering up the existence of aliens, or sometimes collaborating with them and the evidence of the reality of unidentified flying objects is being suppressed. There are many versions of this story; some are exclusive, while others overlap with various other conspiracy theories. They commonly argue that Earth governments, especially the Government of the United States are in fact in communication or cooperation with extraterrestrials, despite public claims to the contrary. Some of these theories claim that the government is explicitly allowing alien abduction in exchange for technology.
Since its inception, the concept has become embedded in popular culture and has become a staple in fiction, making regular appearances on franchises such as Coast to Coast AM and The X-Files.
In the U.S., opinion polls again indicate that a strong majority of people believe the U.S. government is withholding such information. Various notables have also expressed such views. Some examples are astronauts Gordon Cooper and Edgar Mitchell, Senator Barry Goldwater, Vice Admiral Roscoe H. Hillenkoetter (the first CIA director), Lord Hill-Norton (former British Chief of Defense Staff and NATO head), the 1999 high-level French COMETA report by various French generals and aerospace experts, and Yves Sillard (former director of the French space agency CNES, new director of French UFO research organization GEIPAN ).
There is also speculation that UFO phenomena are tests of experimental aircraft or advanced weapons. In this case UFOs are viewed as failures to retain secrecy, or deliberate attempts at misinformation: to deride the phenomenon so that it can be pursued unhindered. This explanation may or may not feed back into the previous one, where current advanced military technology is considered to be adapted alien technology. (See also: Skunk Works and Area 51)
It has also been suggested by a few fringe authors that all or most human technology and culture is based on extraterrestrial contact. See also ancient astronauts.
Allegations of evidence suppression
In 1968, American engineer James A. Harder argued that significant evidence existed to prove UFOs "beyond reasonable doubt," but that the evidence had been suppressed and largely neglected by scientists and the general public, thus preventing sound conclusions from being reached on the ETH.
"Over the past 20 years a vast amount of evidence has been accumulating that bears on the existence of UFO's. Most of this is little known to the general public or to most scientists. But on the basis of the data and ordinary rules of evidence, as would be applied in civil or criminal courts, the physical reality of UFO's has been proved beyond a reasonable doubt " J A Harder
A survey carried out by Industrial Research magazine in 1971 showed that more Americans believed the government was concealing information about UFOs (76 percent) than believed in the existence of UFOs (54 percent), or in ETH itself (32 percent). 
Some also contend regarding physical evidence that it exists abundantly but is swiftly and sometimes clumsily suppressed by governments, aiming to insulate a population they regard as unprepared for the social, theological, and security implications of such evidence. See the Brookings Report.
There have been allegations of suppression of UFO related evidence for many decades. There are also conspiracy theories which claim that physical evidence might have been removed and/or destroyed/suppressed by some governments. (See also Men in Black) Some examples are:
- On July 7, 1947, William Rhodes took photos of an unusual object over Phoenix, Arizona. The photos appeared in a Phoenix newspaper and a few other papers. According to documents from Project Bluebook, an Army counter-intelligence (CIC) agent and an FBI agent interviewed Rhodes on August 29 and convinced him to surrender the negatives. The CIC agent deliberately concealed his true identity, leaving Rhodes to believe both men were from the FBI. Rhodes said he wanted the negatives back, but when he turned them into the FBI the next day, he was informed he wouldn't be getting them back, though Rhodes later tried unsuccessfully.  The photos were extensively analyzed and would eventually show up in some classified Air Force UFO intelligence reports. (Randle, 34-45, full account)
- A June 27, 1950, movie of a "flying disk" over Louisville, Kentucky, taken by a Louisville Courier-Journal photographer, had the USAF Directors of counterintelligence (AFOSI) and intelligence discussing in memos how to best obtain the movie and interview the photographer without revealing Air Force interest. One memo suggested the FBI be used, then precluded the FBI getting involved. Another memo said "it would be nice if OSI could arrange to secure a copy of the film in some covert manner," but if that wasn't feasible, one of the Air Force scientists might have to negotiate directly with the newspaper.  In a recent interview, the photographer confirmed meeting with military intelligence and still having the film in his possession until then, but refused to say what happened to the film after that.
- In another 1950 movie incident from Montana, Nicholas Mariana filmed some unusual aerial objects and eventually turned the film over to the U.S. Air Force, but insisted that the first part of the film, clearly showing the objects as spinning discs, had been removed when it was returned to him. (Clark, 398)
- During the military investigation of green fireballs in New Mexico, UFOs were photographed by a tracking camera over White Sands Proving Grounds on April 27, 1949. The final report in 1951 on the green fireball investigation claimed there was insufficient data to determine anything. However, documents later uncovered by Dr. Bruce Maccabee indicate that triangulation was accomplished. The data reduction and photographs showed four objects about 30 feet in diameter flying in formation at high speed at an altitude of about 30 miles. Maccabee says this result was apparently suppressed from the final report. 
- Project Blue Book director Edward J. Ruppelt reported that, in 1952, a U.S. Air Force pilot fired his jet's machine guns at a UFO, and that the official report which should have been sent to Blue Book was quashed. 1952 newspaper articles of USAF jets being ordered to shoot down saucers
- Astronaut Gordon Cooper reported suppression of a flying saucer movie filmed in high clarity by two Edwards AFB range photographers on May 3, 1957. Cooper said he viewed developed negatives of the object, clearly showing a dish-like object with a dome on top and something like holes or ports in the dome. The photographers and another witness, when later interviewed by Dr.James McDonald, confirmed the story. Cooper said military authorities then picked up the film and neither he nor the photographers ever heard what happened to it. The incident was also reported in a few newspapers, such as the Los Angeles Times. The official explanation, however, was that the photographers had filmed a weather balloon distorted by hot desert air. McDonald, 1968 Congressional testimony, Case 41
- On January 22, 1958, when NICAP director Donald Keyhoe appeared on CBS television, his statements on UFOs were pre-censored by the Air Force. During the show when Keyhoe tried to depart from the censored script to "reveal something that has never been disclosed before," CBS cut the sound, later stating Keyhoe was about to violate "predetermined security standards" and about to say something he wasn't "authorized to release." What Keyhoe was about to reveal were four publicly unknown military studies concluding UFOs were interplanetary (including the 1948 Project Sign, Estimate of the Situation and Project Blue Book's 1952 engineering analysis of UFO motion). (Good, 286-287; Dolan 293-295)
- Astronomer Jacques Vallee reported that in 1961 he witnessed the destruction of the tracking tapes of unknown objects orbiting the Earth. (However, Vallee indicated that this didn't happen because of government pressure but because the senior astronomers involved didn't want to deal with the implications.)
- In 1965, Rex Heflin took four Polaroid photos of a hat-shaped object. Two years later (1967), two men posing as NORAD agents confiscated three prints. Just as mysteriously, the photos were returned to his mailbox in 1993. detailed article and photos
- A March 1, 1967 memo directed to all USAF divisions, from USAF Lt. General Hewitt Wheless, Assistant Vice Chief of Staff, stated that unverified information indicated that unknown individuals, impersonating USAF officers and other military personnel, had been harassing civilian UFO witnesses, warning them not to talk, and also confiscating film, referring specifically to the Heflin incident. AFOSI was to be notified if any personnel were to become aware of any other incidents. (Document in Fawcett & Greenwood, 236).
- John Callahan, former Division Chief of the Accidents and Investigations Branch of the FAA, Washington D.C., also a Disclosure Project witness, said that following a 1986 encounter of a Japanese airlines 747 with a giant UFO over Alaska, recorded by air and ground radar, the FAA conducted an investigation. Callahan held a briefing a few days later for President Reagan's Scientific Study Group, the FBI, and CIA. After the briefing, one of the CIA agents told everybody they "were never there and this never happened," adding they were fearful of public panic. 
- In 1996, the CIA revealed an instance from 1964 where two CIA agents posed as USAF representatives in order to recover a film canister from a Corona spy satellite that had accidentally come down in Venezuela. The event was then publicly dismissed as an unsuccessful NASA space experiment.
See Wikipedia: UFO conspiracy theory
II. UFOs as perception or illusion
II.1 The mistaken observer hypothesis
This is a theory that most UFO sightings are misunderstood phenomena such as ball lightning or visual illusions. See Identified Flying Objects (IFOs).
II.2 The Unknown Natural Phenomena hypothesis
UFOs are unkown natural phenomena (e.g. ball lightning, sprites)
The Meteorological hypothesis
Peter F Coleman advanced a meteorological theory that many UFOs or unexplained lights are actually instances of visible combustion of a fuel (e.g., natural gas) inside an atmospheric vortex. He has argued his case in his book, Great Balls of Fire–a unified theory. This vortex fireball theory was first published in Weather, and later in the Journal of Scientific Exploration
II.3 Psychosocial hypothesis
The Psychosocial Hypothesis (PSH) advocated in the early work of Hilary Evans, this theory posits that some UFO sightings are hallucinations or fantasies and are caused by the same mechanism as various occult, paranormal, supernatural or religious experiences (compare alleged sightings of the Blessed Virgin Mary).
In ufology, the psychosocial or psychocultural hypothesis, colloquially abbreviated PSH or PCH, argues that at least some UFO reports are best explained by psychological or social means. It is often contrasted with the better known extraterrestrial hypothesis (ETH), and is particularly popular among UFO researchers in the United Kingdom, such as David Clarke, Hilary Evans, the editors of Magonia magazine, and many of the contributors to Fortean Times magazine. It is also popular in France since the publication in 1977 of a book written by Michel Monnerie, Et si les ovnis n'existaient pas? (What if ufos do not exist?).
UFOlogists claim that the psychocultural hypothesis is occasionally confused with aggressive anti-ETH debunking, but that there is an important difference in that the PCH researcher sees UFOs as an interesting subject that is worthy of serious study, even if it is approached in a skeptical (i.e. non-credulous) way.
The psychocultural hypothesis is not a single, all-encompassing explanation of the UFO phenomenon, but explains different cases in different ways, all centering in some way on human behavior. Examples of PCH explanations are wishful thinking, hallucinations, hoaxes and misidentification of mundane objects. Because of its emphasis on human behavior, it attempts to explain why such a phenomenon is interpreted the way it has been, sometimes through pre-existing motifs and memetic selection.
One of the arguments in favor of the psychocultural hypothesis compared with less mainstream interpretations (e.g. interdimensional "tricksters" or extraterrestrial visitors) is that the latter lie outside the body of knowledge currently accepted by science whereas the PCH does not (cf. Occam's razor).
The route followed by these misperceptions can be influenced by the environment that the perceiver was brought up in as a child: fairy stories, or one or other religion, or science fiction, etc: for example, one perceiver may see fairies where another sees Greys.
Several authors underline the fact that the science-fiction magazines, stories, etc., curiously predate the UFO phenomena. Bertrand Méheust, a French sociologist, in his 1978 book Science-fiction et soucoupes volantes (Science-Fiction and flying saucers), shows that almost every aspect of the UFO phenomena can be located in pulp magazines of the beginning of the 20th century, well before the beginning of the UFO phenomena in 1947 (Kenneth Arnold sighting).
In the same vein, in his article The truth is: They never were saucers, Robert Sheaffer underlines the fact that just after the Kenneth Arnold case, most of the witness described UFOs according to the media coverage of the event, but not according to the factual descriptions of the objects made by Arnold himself, demonstrating the importance of the culture in UFO narratives.
Carl G. Jung, the Swiss psychoanalyst, in his 1957 work, Flying Saucers: A Modern Myth of Things Seen in the Skies, explained UFOs as objects of the collective unconscious and modern archetypes. Paradoxically, in a brief final chapter of his book, Jung also expressed his opinion that some UFOs were real "nuts-and-bolts" craft, citing corroborating physical evidence. With his essay he can be seen as one of the founding father of the PSH. On the other hand, because of his use of the concept of synchronicity in this book, he is also one of the founding father of paranormal explanations of the UFO phenomena.
In psychology, the study of UFO sightings has revealed information on misinterpretation, perceptual illusions, hallucination. Many have questioned the reliability of hypnosis in UFO abduction cases.
UFO-related claims that are based solely on eyewitness accounts are subject to a range of issues that may be involved with eyewitness memory. Under some circumstances, eyewitness memory is unreliable. In addition, there is some evidence that memory of an event can be unconsciously altered to suit a desired interpretation of what was remembered. For example, it is possible a person who has reported a UFO sighting may be reinterpreting an older memory to fit a desired explanation. One study has reported that participants who reported recovered memories of abduction by aliens were more prone than a control group to exhibit false recall. However, the authors note as a limitation, that a small sample size was used in the study. In addition, the study did not address the alternative hypothesis that only a subgroup of those who reported abductions could account for the observed differences; i.e. it is possible some of the group claiming abduction were more prone to false recall while others were not.
Some authors have argued that the UFO phenomena shows aspects of a mass hysteria, especially during UFO Waves. The French psychiatrist George Heuyer wrote this hypothesis in 1954 in a note to the Bulletin de l’Académie Nationale de Médecine .
II.4 The Tectonic Strain and electro-staging theories
A number of theorists have concluded that, jointly, Earthlight lights (a somewhat disputed phenomenon within the mainstream scientific community) and the effect of natural (and in some cases artificial electromagnetic radiation) causes altered states of consciousness.
Persinger has also come to public attention due to his 1975 Tectonic Strain Theory (TST) of how geophysical variables may correlate with sightings of unidentified flying objects (UFOs). Persinger argued that strain within the earth's crust near seismic faults produces intense electromagnetic (EM) fields, creating bodies of light that some interpret as glowing UFOs. Alternatively, he argued that the EM fields generate hallucinations in the temporal lobe, based on images from popular culture, of alien craft, beings, communications, or creatures.
Canadian researcher Chris Rutkowski of the University of Manitoba has become a prominent harsh critic of Persinger's Tectonic Strain Theory. For one thing, Rutowski argues, in order to try to accommodate UFO sightings in regions far removed from faults, Persinger has claimed that UFO-like lights or hallucinations can manifest hundreds of miles away from an area of seismic activity. Not only does this place an absurdly great distance between the actual area of tectonic stress and the surmised significant EM field, it also makes the theory unscientific by destroying any possible predictive power. Nearly every place on the planet lies within a few hundred miles of a seismically active area. Rutkowski pointed out severe flaws in Persinger's statistical methodology, since he confused possible correlation (however weak) with causality. For example, one could more easily explain occasional clusters of UFO sightings along earthquake fault-lines by the fact that populations often occur there in higher densities and by the fact that transportation routes often follow major fault lines, such as the San Andreas fault in California.
As with criticisms of Persinger's claims that minute laboratory magnetic fields can invoke hallucinations, Rutowski also points out that Persinger's inferred seismic EM fields would have much less influence than what people commonly experience near electrical appliances like television sets or hair driers. This again raises the question as to why people don't experience UFOs or aliens far more often than they do, or why these hypothetical hallucinations from electrical devices wouldn't drown out any possible contribution from much weaker geophysical fields. Once again, Persinger notes that the magnitude of the EM fields may have less significance than the particular temporal patterns. Furthermore, commentators such as British researcher Albert Budden, has proposed that man-made electromagnetic emissions can (in certain circumstances) generate close encounter experiences and has cited possible examples of this effect in his work Electric UFOs (Blandford, 1998).
In the UK, Paul Devereux advocates a variant geophysical theory similar to TST, the Earthlights theory. However, unlike Persinger, Devereaux generally restricts such effects to the immediate vicinity of a fault line. Devereux's approach also differs from Persinger's in holding triboluminescence rather than piezoelectricity as the "more likely candidate" for the production of naturally occurring UFOs. Devereux doesn't advocate, as in Persinger's TST, that the phenomenon might create hallucinations of UFO encounters in people, instead proposing an even more radical hypothesis: that earthlights may possess intelligence and even have the ability to read witness' thoughts. 
UFO researchers critical of the sesmic stress theory admit that, while, observations of diffuse lights during (and sometimes before and after) very severe earthquakes may give some weak support to some parts of TST and Earthlights theory (see Earthquake lights), they question the ability of fault lines to generate luminous effects and hallucinatory experiences under much less severe conditions(as cited above). Nonetheless, even TST critics such as Rutowski think such theories may hold some promise for explaining a small percentage of UFO phenomena, although they doubt that they can ever offer a comprehensive explanation for the vast majority of unexplained UFO cases. Other UFO researchers (mainly in the U.K) believe this very limited interpretation of the TST is brought into question by the clustering of UFO reports within areas prone to faulting - such as the Pennine region of northern Britain. While acknowledging the drawback's of Persinger's theory, they feel that amended versions of it may account for a significant proportion of "True UFO" reports.
See Wikipedia: Tectonic Strain Theory
Related Articles on Wikipedia
to be continued...
- Thomas E. Bullard, "UFOs: Lost in the Myths", pages 141–191 in "UFOs, the Military, and the Early Cold War Era", pages 82–121 in "UFOs and Abductions: Challenging the Borders of Knowledge" David M. Jacobs, editor; 2000, University Press of Kansas, ISBN 0-7006-1032-4
- Jerome Clark, The UFO Book: Encyclopedia of the Extraterrestrial, 1998, Visible Ink Press, ISBN 1-57859-029-9. Many classic cases and UFO history provided in great detail; highly documented.
- J. Deardorff, B. Haisch, B. Maccabee, Harold E. Puthoff (2005). "Inflation-Theory Implications for Extraterrestrial Visitation". Journal of the British Interplanetary Society 58: 43–50.
- Curran, Douglas. In Advance of the Landing: Folk Concepts of Outer Space. (revised edition), Abbeville Press, 2001. ISBN 0-7892-0708-7. Non-sensational but fair treatment of contemporary UFO legend and lore in N. America, including the so-called "contactee cults." The author traveled the United States with his camera and tape recorder and directly interviewed many individuals.
- Hall, Richard H., editor. The UFO Evidence: Volume 1. 1964, NICAP, reissued 1997, Barnes & Noble Books, ISBN 0-7607-0627-1. Well-organized, exhaustive summary and analysis of 746 unexplained NICAP cases out of 5000 total cases — a classic.
- Hall, Richard H. The UFO Evidence: A Thirty-Year Report. Scarecrow Press, 2001. ISBN 0-8108-3881-8. Another exhaustive case study, more recent UFO reports.
- Hendry, Alan. The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings. New York: Doubleday & Co., 1979. ISBN 0-385-14348-6. Skeptical but balanced analysis of 1300 CUFOS UFO cases.
- Hynek, J. Allen. The UFO Experience: A scientific inquiry. Henry Regnery Co., 1972.
- Hynek, J. Allen. The Hynek UFO Report. New York: Barnes & Noble Books, 1997. ISBN 0-7607-0429-5. Analysis of 640 high-quality cases through 1969 by UFO legend Hynek.
- Rose, Bill and Buttler, Tony. Flying Saucer Aircraft (Secret Projects). Leicester, UK: Midland Publishing, 2006. ISBN 1-85780-233-0.
- Sagan, Carl & Page. Thornton, editors. UFOs: A Scientific Debate. \Cornell University Press, 1996. ISBN 0-7607-0192-2. Pro and con articles by scientists, mostly to the skeptical side.
- Sheaffer, Robert The UFO Verdict: Examining the Evidence, 1986, Prometheus Books ISBN 0-87975-338-2
- Sheaffer, Robert UFO Sightings: The Evidence, 1998, Prometheus Books, ISBN 1-57392-213-7 (revised edition of The UFO Verdict)
- Sturrock, Peter A. (1999). The UFO Enigma: A New Review of the Physical Evidence. New York: Warner Books. ISBN 0-446-52565-0
- Canada's Unidentified Flying Objects: The Search for the Unknown, a virtual museum exhibition at Library and Archives Canada
- Carl G. Jung : "Flying Saucers: A Modern Myth of Things Seen in the Skies" (translated by R.F.C. Hull); 1979, Princeton University Press, ISBN 0-691-01822-7
- Armando Simon :"A Nonreactive, Quantitative Study of Mass Behavior with Emphasis on the Cinema as Behavior Catalyst," Psychological Reports, 1981, 48, 775-785.
- Richard Haines : "UFO Phenomena and the Behavioral Scientist." Metuchen: Scarecrow Press, 1979.
- Armando Simon : "UFOs: Testing for the Existence of Air Force Censorship." Psychology, 1976, 13, 3-5.
- Armando Simon : "Psychology and the UFOs." The Skeptical Inquirer. 1984, 8, 355-367.
- Richard M. Dolan, UFOs and the National Security State: An Unclassified History, Volume One: 1941–1973, 2000, Keyhole Publishing, ISBN 0-9666885-0-3. Dolan is a professional historian.
- Downes, Jonathan Rising of the Moon. 2nd ed. Bangor: Xiphos, 2005.
- Lawrence Fawcett & Barry J. Greenwood, The UFO Cover-Up (Originally Clear Intent), 1992, Fireside Books (Simon & Schuster), ISBN 0-671-76555-8. Many UFO documents.
- Timothy Good, Above Top Secret, 1988, William Morrow & Co., ISBN 0-688-09202-0. Many UFO documents.
- Timothy Good, Need to Know: UFOs, the Military, and Intelligence, 2007, Pegasus Books, ISBN 978-1-933648-38-5. Update of Above Top Secret with new cases and documents
- Bruce Maccabee, UFO FBI Connection, 2000, Llewellyn Publications, ISBN 1-56718-493-6
- Kevin Randle, Project Blue Book Exposed, 1997, Marlowe & Company, ISBN 1-56924-746-3
- Edward J. Ruppelt, The Report On Unidentified Flying Objects, 1956, Doubleday & Co. online. A UFO classic by insider Ruppelt, the first head of the USAF Project Blue Book
- LeRoy F. Pea, Government Involvement in the UFO Coverup, or earlier title History of UFO Crash/Retrievals", 1988, PEA RESEARCH.
- Paul R. Hill, Unconventional Flying Objects: a scientific analysis, 1995, Hampton Roads Publishing Co., ISBN 1-57174-027-9. Analysis of UFO technology by pioneering NACA/NASA aerospace engineer.
- James M. McCampbell, Ufology: A Major Breakthrough in the Scientific Understanding of Unidentified Flying Objects, 1973, 1976, Celestial Arts, ISBN 0-89087-144-2 full-text online. Another analysis by former NASA and nuclear engineer.
- James M. McCampbell, Physical effects of UFOs upon people, 1986, paper.
- Antonio F. Rullán, Odors from UFOs: Deducing Odorant Chemistry and Causation from Available Data, 2000, preliminary paper.
- Jack Sarfatti, "Super Cosmos", 2005 (Authorhouse)
- S. Krasnikov (2003). "The quantum inequalities do not forbid spacetime shortcuts". Physical Review D 67: 104013. doi:10.1103/PhysRevD.67.104013. See also the "eprint version". arXiv.<
- L. H. Ford and T. A. Roman (1996). "Quantum field theory constrains traversable wormhole geometries". Physical Review D 53: 5496. doi:10.1103/PhysRevD.53.5496. See also the "eprint". arXiv.
(a truly hopeless ordeal):
-  Why SETI Is Science and UFOlogy Is Not - A Space Science Perspective on Boundaries, Mark Moldwin, 2004
-  A degree in strange flying objects alien no longer, Sydney Morning Herald, August 5, 2008
-  Westrum, Ron; Jacobs, David Michael (ed.) (2000). "Limited Access: Six Natural Scientists and the UFO Phenomenon". UFOs and abductions: Challenging the Borders of Knowledge. Lawrence, Kansas: University Press of Kansas. pp. 30–55. ISBN 0700610324.
-  Friedman, S. (2008). Flying Saucers and Science: A Scientist Investigates the Mysteries of UFOs. Franklin Lakes, NJ: New Page Books ISBN: 978-1-60163-011-7
-  Sturrock, 163
-  Hynek, Josef Allen (April 1953). "Unusual Aerial Phenomena". Journal of the Optical Society of America 43 (4): 311–314.
-  Josef Allen Hynek (1952-08-06). "Special report on conferences with astronomers on unidentified aerial objects". NARA. Retrieved on 2007-05-25. (page 13)
-  a, b, c Sheaffer, Robert. "A Skeptical Perspective on UFO Abductions." In: Pritchard, Andrea & Pritchard, David E. & Mack, John E. & Kasey, Pam & Yapp, Claudia. Alien Discussions: Proceedings of the Abduction Study Conference. Cambridge: North Cambridge Press. Pp. 382-388.
-  name = McDonald
-  McDonald, James. E. (1968). Statement on Unidentified Flying Objects submitted to teh House Committee on Science and Astronautics at July 29, 1968, Symposium on Unidentified Flying Objects, Rayburn Bldg., Washington, D.D.
-  Herb/Hynek amateur astronomer poll results reprinted in International UFO Reporter (CUFOS), May 2006, pp. 14-16
-  "Pdf document on UFOs and Clyde Tombaugh" (PDF).
-  Full quote in Clyde Tombaugh article; originally  and [Virtually Strange.net]
-  "Menzel's sighting". Retrieved on 2008-01-12.
-  Cramer, John G.. "NASA Goes FTL Part 1: Wormhole Physics". Retrieved on 2006-12-02.
-  Visser, Matt; Sayan Kar, Naresh Dadhich (2003). "Traversable wormholes with arbitrarily small energy condition violations". Physical Review Letters 90: 201102.1–201102.4. doi:10.1103/PhysRevLett.90.201102. arΧiv:gr-qc/0301003
- ^ Good (1988), 484
- ^ Good (1988), 23
- ^ Document quoted and published in Timothy Good (2007), 106-107, 115; USAFE Item 14, TT 1524, (Top Secret), 4 November 1948, declassified in 1997, National Archives, Washington D.C.
- ^ Good (1988), 426-427; excerpt from Fontes letter
- ^ Dolan, 189; Good, 287, 337; Ruppelt, Chapt. 16
- ^ Good, 347
- ^ 1960s Condon Report A Whitewash
- ^ 'Yes, UFOs exist': Position statement by SEPRA head, Jean-Jacques Velasco - UFO Evidence
- ^ Official French Gov't UFO study project to resume with new director - UFO Evidence
- ^ USA: UFOs and National Security - UFO Evidence
- ^ Best UFO Cases III: Belgium, 1989-1990 - UFO Evidence
- ^ UFO Evidence : JAL Flight 1628 Over Alaska
- ^ Trans-en-Provence Physical Trace Case - Trans-en-Provence, France - January 8, 1981 - UFO Evidence
- ^ Chapter Thirteen: The Report On Unidentified Flying Objects
- ^ UFO Evidence : Physical Trace Cases
- ^ Top Physical Trace Cases - Cases of High Strangeness - A Preliminary List - UFO Evidence
- ^ Letter to Scientific American, Dec 18, 1886
- ^ UFO Evidence : Electromagnetic Effects
- ^ A Preliminary Study of Sixty Four Pilot Sighting Reports - Involving Alleged Electromagnetic Effects on Aircraft Systems
- ^ Tehran, Iran/ F-4 Incident
- ^ Iranian Jet Case
- ^ UFO - UFOS at close sight: Blue Book's Captain Ruppelt's book, chapter 15, the radiation story
- ^ ufo - UFOS at close sight: RB-47 radar visual multiple witnesses cases, July 17, 1957
- ^ UFO Symposium 1968: Harder Statement
- ^ Table of Contents for "Physical Evidence Related to UFO Reports"
- ^ Myrabo, Leik N
- ^ Eyewitness memory in context: toward a systematic understanding
- ^ Today@UCI: Press Releases:
- ^ Jacques and Janine Vallee: Challenge To Science: The UFO Enigma, LC# 66-25843
- ^ Scientific Study of Unidentified Flying Objects, Section II Summary of the Study, Edward U. Condon, University of Colorado
- ^ See also Wilhelm Reich#Orgone accumulators and cloudbusters
- ^ Snippy the Horse -the Most Famous Horse in the World! official website
- ^ "The cosmic pulse of life", by Trevor Constable
- ^ burlingtonnews.net: UFOs OVER BURLINGTON WISCONSIN
-  "Reuters news article concerning the press conference" . Retrieved on 2007-11-12.
-  "ABC News West Palm Beach video file on the press conference". Retrieved on 2007-11-12.
-  "CNN article about the press conference". Retrieved on 2007-11-12.
-  "AFP via Yahoo article about the press conference". Retrieved on 2007-11-13.
-  "BBC article concerning the press conference". Retrieved on 2007-11-13.
-  "Full video taken during the press conference". Retrieved on 2008-01-14.
-  Brake, Mark (June 2006). "On the plurality of inhabited worlds;a brief history of extraterrestrialism". International Journal of Astrobiology 5 (2): 104. doi:10.1017/S1473550406002989.
-  Denzler, Brenda (2003). The lure of the edge: scientific passions, religious beliefs, and the pursuit of UFOs. University of California Press. pp. 6–7. ISBN 0-520-23905-9.
-  Denzler (2003), pp. 9
-  Schulgen, George (October 28, 1947). "Schulgen Memo". Retrieved May 3, 2010. "the object sighted is being assumed to be a manned aircraft, of Russian origin, and based on the perspective thinking and actual accomplishments of the Germans."
-  "The Air Force Intelligence Report". Retrieved May 3, 2010. "To implement this policy it was directed that Hq, Air Material Command set up a project with the purpose of collecting, collating, evaluating, and distributing to interested government agencies and contractors, all information concerning sightings and phenomena in the atmosphere which could be construed to be of concern to the national security."
-  Haines, Gerald K. (April 14, 2007). "CIA's Role in the Study of UFOs, 1947-90". Retrieved May 3, 2010.
-  GEIPAN stands for Groupe d'Études et d'Informations sur les Phénomènes Aérospatiaux Non-identifiés ("unidentified aerospace phenomenon research and information group")
-  UFO files from the UK National Archives
-  UFO files from the Library and Archives Canada
-  "Secret UFO archives opened". The Copenhagen Post. January 29, 2009. Retrieved May 3, 2010.
-  Italian Air Force » UFO site (in Italian)
-  "För insyn: 18 000 svenska UFO-rapporter" (in Swedish). Expressen. May 6, 2009. Retrieved May 3, 2010.
-  "UFO reports to be destroyed in future by MoD". Telegraph (London). February 28, 2010. Retrieved May 3, 2010.
» Ufology - UFOs - Unidentified Flying Objects