An unidentified flying object or UFO is a popular term for any aerial phenomenon whose cause cannot be easily or immediately determined. Popular culture frequently takes the term UFO as a synonym for alien spacecraft.

Unexplained aerial observations have been reported throughout history. Some were undoubtedly astronomical in nature such as comets, bright meteors, or atmospheric optical phenomena such as parhelia and lenticular clouds. Sightings throughout history were often treated as supernatural portents, angels, or other religious omens. Some objects in medieval paintings are strikingly similar to UFO reports. Art historians explain those objects as religious symbols, often represented in many other paintings during the Renaissance.

Carl Jung theorized that UFOs might have a primarily spiritual and psychological basis. 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, defining them as 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. 

It has been speculated that UFOs might have their origins not in space and time as we know it, but outside of it. There has been noted an almost exact parallel between UFOs and  visitations from folklore of fairies and similar creatures. The significance of these parallels is disputed between mainstream scientists, who contend that they are fanciful demonstrations of a poorly understood phenomenon interacting with humans to cause the 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.

A large part of the available UFO literature today 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 or ghost manifestations and possession. Many of the UFO reports now being published in the popular press recount alleged incidents that are strikingly similar to psychic phenomena.

Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes’ different positions in the head.

The effect appears to be processed in the visual cortex in binocular cells having receptive fields in different horizontal positions in the two eyes. Such a cell is active only when its preferred stimulus is in the correct position in the left eye and in the correct position in the right eye, making it a disparity detector.

Because each eye is in a different horizontal position, each has a slightly different perspective on a scene yielding different retinal images. Normally two images are not observed, but rather a single view of the scene, a phenomenon known as singleness of vision. Nevertheless, stereopsis is possible with double vision. 

Stereopsis was first described by Charles Wheatstone in 1838. He recognized that because each eye views the visual world from slightly different horizontal positions, each eye’s image differs from the other. Objects at different distances from the eyes project images in the two eyes that differ in their horizontal positions, giving the depth cue of horizontal disparity, also known as retinal disparity and as binocular disparity. Wheatstone showed that this was an effective depth cue by creating the illusion of depth from flat pictures that differed only in horizontal disparity. To display his pictures separately to the two eyes, Wheatstone invented the stereoscope.

Leonardo da Vinci had also realized that objects at different distances from the eyes project images in the two eyes that differ in their horizontal positions, but had concluded only that this made it impossible for a painter to portray a realistic depiction of the depth in a scene from a single canvas.

Stereopsis became popular during Victorian times with the invention of the prism stereoscope by David Brewster. This, combined with photography, meant that tens of thousands of stereograms were produced.

In the 1960s, Horace Barlow, Colin Blakemore, and Jack Pettigrew found neurons in the cat visual cortex that had their receptive fields in different horizontal positions in the two eyes. This established the neural basis for stereopsis. Their findings were disputed by David Hubel and Torsten Wiesel, although they eventually conceded when they found similar neurons in the monkey visual cortex. In the 1980s, Gian Poggio and others found neurons in the monkey brain that responded to the depth of random dot stereograms.

In the 1970s, Christopher Tyler invented autostereograms, random-dot stereograms that can be viewed without a stereoscope. This led to the popular Magic Eye pictures.

Nensha, better known to English speakers as thoughtography or projected thermography, is the ability to psychically “burn” images from one’s mind onto surfaces, or even into the minds of others. There are three well known individuals involved in thoughtography or the research of it.

Tomokichi Fukurai, an assistant professor of psychology at Tokyo University and a firm believer in the supernatural, took a woman named Ikuko Nagao under his wing. Unlike his previous failed experimentation with clairvoyant Chizuko Mifune earlier that year, Fukurai was determined to prove his claims as true and decided to work with Nagao’s skill, a talent he labeled nensha, or spirit photography. Unfortunately, Nagao’s efforts were labelled as fraudulent. However, Fukurai was undeterred, and worked with other nensha practitioners but found little success.

In 1913, Fukurai took on a subject that would advance his claims further, a woman named Sadako Takahashi. Takahashi, who claimed to have developed both clairvoyance and nensha through breathing and mental exercises, met Fukurai and soon was able to breathe life into his sagging studies. She was able to convince enough skeptics and later that year Fukurai published a book called Toshi to Nensha, later translated and published throughout the world as Clairvoyance and Thoughtography. Fukurai would later work with another nensha practitioner, Koichi Mita, who was said to create a thoughtograph of the dark side of the moon.

In the end, however, Fukurai’s theories never gained widespread popularity, and in 1919, he resigned his post at the university to continue his research. Before his death in 1952, Fukurai founded the Fukurai Institute of Psychology, an organization that studies the paranormal and still survives to this day.

In the 1960s, Chicago resident Ted Serios became notorious for the production of nensha on Polaroid film supposedly using only his psychic powers. His abilities were endorsed by Jule Eisenbud, a Denver based psychiatrist who wrote a book lauding Serios’ talents called The World of Ted Serios: “Thoughtographic” Studies of an Extraordinary Mind. Serios’ images, which often appeared surrounded by dark areas on the film, were often of typical postcard scenes. Serios was eventually only able to produce his photographs while holding a device to his forehead, which has been described as a small section of tubing fitted with a piece of photo squeegee.

As Eisenbud’s book readily admits, many of Serios’ thoughtographs were produced while Serios was drunk or drinking alcohol. According to Eisenbud, “Ted Serios exhibits a behavior pathology with many character disorders. He does not abide by the laws and customs of our society. He ignores social amenities and has been arrested many times. His psychopathic and sociopathic personality manifests itself in many other ways. He does not exhibit self control and will blubber, wail and bang his head on the floor when things are not going his way.”

In 1995, famed psychic Uri Geller began to perform nensha by using a 35mm camera upon which the lens cap would be left on. He would then take pictures of his forehead and have the pictures developed, to which Geller claimed that the images had come directly from his mind. Stage magician and skeptic James Randi immediately criticized the event, claiming fraud on Geller’s part. Randi states that Geller is using already exposed film in the camera, a charge Geller has consistently denied.

Professional photographer Nile Root was present at the March 1966 session where Serios claimed to have created thoughtographs and states that the small, handheld device Serios used was in many ways a miniaturized daguerreotype maker, creating the pictures in this manner. Furthermore, Root charges that Serios’ wild manner and actions may have been a distraction to insert the object into the device which would then expose the film. Root has since then given extensive details on how he believes the thoughtographs were created, as well as digital versions of the same.

The Hering illusion is an optical illusion discovered by the German physiologist Ewald Hering in 1861. The two lines are both straight, but they look as if they were bowing outwards. The distortion is produced by the lined pattern on the background, that simulates a perspective design, and creates a false impression of depth.

The Hering illusion looks like bike spokes around a central point, with lines on either side of this central, so called vanishing point. The illusion tricks us into thinking we are moving forward. Since we aren’t actually moving and the figure is static, we misperceive the straight lines as curved ones.

Researcher Mark Changizi of Rensselaer Polytechnic Institute in New York says optical illusions are due to a neural lag which most humans experience while awake. When light hits the retina, about one tenth of a second goes by before the brain translates the signal into a visual perception of the world. Scientists have known of the lag, yet they have debated over how humans compensate, with some proposing that our motor system somehow modifies our movements to offset the delay.

Changizi asserts that the human visual system has evolved to compensate for neural delays, generating images of what will occur one tenth of a second into the future. This foresight enables human to react to events in present. This allows humans to perform reflexive acts like catching a fly ball and to maneuver smoothly through a crowd. Illusions occur when our brains attempt to perceive the future, and those perceptions don’t match reality. The Hering illusion tricks us into thinking we are moving forward, and thus, switches on our future seeing abilities. Since we aren’t actually moving and the figure is static, we misperceive the straight lines as curved ones.

Chnagizi says, ”Evolution has seen to it that geometric drawings like this elicit in us premonitions of the near future. The converging lines toward a vanishing point are cues that trick our brains into thinking we are moving forward as we would in the real world, where the pair of lines seems to bow out as we move through it, and we try to perceive what that world will look like in the next instant.”

Popcorn was first discovered thousands of years ago by the Native Americans, who believed that the popping noise was that of an angry god who escaped the kernel. 

Each kernel of popcorn contains a certain amount of moisture and oil. Corn is able to pop because, unlike other grains, the outer hull of the kernel is both strong and impervious to moisture, and the starch inside consists almost entirely of a dense starchy filling. This allows pressure to build inside the kernel until an explosive pop results.

As the oil and the water are heated past the boiling point, they turn the moisture in the kernel into a superheated pressurized steam, contained within the moisture proof hull. Under these conditions, the starch inside the kernel gelatinizes, softening and becoming pliable. The pressure continues to increase until the breaking point of the hull is reached, a pressure of about 135 psi and a temperature of 356 °F. The hull ruptures rapidly, causing a sudden drop in pressure inside the kernel and a corresponding rapid expansion of the steam, which expands the starch and proteins of the endosperm into airy foam. As the foam rapidly cools, the starch and protein polymers set into the familiar crispy puff.

During the Great Depression, popcorn was comparatively cheap at 5 to 10 cents a bag and became popular. Thus, while other businesses failed, the popcorn business thrived and became a major source of income for some struggling farmers. During World War II, sugar rations diminished candy production causing Americans to eat three times more popcorn than they had before.

At least six localities, all in the United States, claim to be the Popcorn Capital of the World: Valparaiso, Indiana; Van Buren, Indiana; Marion, Ohio; Ridgway, Illinois; Schaller, Iowa; and North Loup, Nebraska. According to the USDA, most of the maize used for popcorn production is specifically planted for this purpose. Most is grown in Nebraska and Indiana, with increasing area in Texas. As the result of an elementary school project, popcorn became the official state snack food of Illinois. 

Popcorn, threaded onto a string, is used as a wall or Christmas tree decoration in some parts of North America, as well as on the Balkan peninsula. The world’s largest popcorn ball was unveiled in October 2006 in Lake Forest, Illinois. It weighed 3,415 pounds, measured 8 feet in diameter, and had a circumference of 24.6 feet.

Dowsing, sometimes called doodlebugging, divining or water witching, is a practice that attempts to locate hidden water wells, buried metals, gemstones, or other objects as well as currents of earth radiation without the use of scientific apparatus. It has been in use since ancient times and is still widely practiced although the scientific evidence for its credibility is disputed.

Traditionally, the most common dowsing rod was a “Y” shaped branch from a tree or bush. Some dowsers prefer branches from particular trees. Many dowsers today use a pair of simple “L” shaped metal rods, and some use bent wire coat hangers. One rod is held in each hand, with the short part of the “L” held upright, and the long part pointing forward. Some dowsers claim best success with rods made of particular metals such as brass.

Pendulums such as a crystal or a metal weight suspended on a chain are sometimes used in divination and dowsing, particularly in remote dowsing. The person holding the pendulum aims to hold it as steadily as possible over the center. An interviewer may pose questions to the person holding the pendulum, and it swings by minute unconscious bodily movement in the direction of the answer. In the practice of radiesthesia, a pendulum is used for medical diagnosis.

Both skeptics of dowsing and many of dowsing’s supporters believe that dowsing apparatus have no special powers, but merely amplify small imperceptible movements of the hands arising from the expectations of the dowser. This psychological phenomenon is known as the idiomotor effect. Some supporters agree with this explanation, but maintain that the dowser has a subliminal sensitivity to the environment, perhaps via electroception, magnetoception, or telluric currents. Other dowsers say their powers are paranormal.

In a scientific study in Munich 500 dowsers were initially tested for their skill, and the experimenters selected the best 43 among them. On the ground floor of a two story barn, water was pumped through a pipe. Before each test, the pipe was moved in a direction perpendicular to the water flow. On the upper floor, each dowser was asked to determine the position of the pipe. Over two years, the 43 dowsers performed 843 tests, and of the 43 selected and extensively tested candidates, at least 37 of them showed no dowsing ability. The results from the remaining 6 were said to be better than chance, resulting in the conclusion that some dowsers showed an extraordinarily high rate of success, which can scarcely be explained as due to chance.

Recently, a study was undertaken in Kassel, Germany, under the direction of the Society for the Scientific Investigation of the Parasciences. The three day test of some 30 dowsers involved plastic pipes through which a large flow of water could be controlled and directed. The pipes were buried 50 centimeters under a level field. On the surface, the position of each pipe was marked with a colored stripe, so all the dowsers had to do was tell whether there was water running through the pipe. All the dowsers signed a statement agreeing this was a fair test of their abilities and that they expected a 100 percent success rate. However, the results were no better than what would have been expected by chance.

Some researchers have investigated possible physical or geophysical explanations for dowsing abilities. For example, Soviet geologists have made claims for the abilities of dowsers which are difficult to account for in terms of the reception of normal sensory cues. Some authors suggest that these abilities may be explained by postulating human sensitivity to small magnetic field gradient changes. One study concludes that dowsers respond to a 60 Hz electromagnetic field, but this response does not occur if the kidney area or head are shielded.

The Tanganyika laughter epidemic of 1962 was an outbreak of mass psychogenic illness rumored to have occurred in the vicinity of the village of Kashasha on the western coast of Lake Victoria in the modern nation of Tanzania near the border of Kenya. It is possible that, at the start of the incident, a joke was told in a boarding school, and that this joke triggered a small group of students to start laughing. The laughter perpetuated itself, far transcending its original cause.

The epidemic is often understood as implying that thousands of people were continuously laughing for months. However, since it is physiologically impossible to laugh for much more than a few minutes at a time, the laughter must have made itself known no more than sporadically. The epidemic reportedly consisted of occasional attacks of laughter among groups of people, occurring throughout the vicinity of the village of Kashasha at irregular intervals. According to reports, the laughter was incapacitating when it struck.

The school from which the epidemic sprang was shut down, but the children and parents transmitted the laughter to the surrounding areas. Other schools, Kashasha itself, and another village, comprising thousands of people, were all affected to some degree. Six to eighteen months after it started, the phenomenon died off. Other symptoms were reported on an equally massive scale as the reports of the laughter itself, such as, fainting, respiratory problems, rashes, and attacks of crying.

There are only a few reports of this occurrence. These reports have been embellished and misquoted. In cases of mass psychogenic illness there are often not many reports of the incident. Due to its nature the incident has been confused with positive humorous or infectious laughter as seen in phenomena like the holy laughter movement. The nature of mass psychogenic illness, however, is quite dissimilar to these euphoric experiences.

Charles Fort was a Dutch-American writer and researcher into anomalous phenomena. His books sold well and remain in print. Today, the term Fortean is used to characterize various anomalous phenomena.

Fort’s relationship with the study of anomalous phenomena is frequently misunderstood and misrepresented. For over thirty years, Charles Fort sat in the libraries of New York and London, diligently reading scientific journals, newspapers and magazines, collecting notes on phenomena that lay outside the accepted theories and beliefs of the time.

In his lifetime he took tens of thousands of notes. The notes were kept on cards in shoeboxes. They were inscribed on small squares of paper in a cramped shorthand of Fort’s own invention, and some of them survive today in the collections of the University of Pennsylvania. More than once, depressed and discouraged, Fort destroyed his work but always began again.

Examples of the odd phenomena in Fort’s writings include many of what are variously referred to as occult, supernatural, and paranormal. Reported events include teleportation, poltergeist events, unaccountable noises and explosions, spontaneous fires, levitation, and unexplained disappearances. He offered many reports of out of place artifacts and strange items found in unlikely locations. He is also the first person to explain strange human appearances and disappearances by the hypothesis of alien abduction and was an early proponent of the extraterrestrial hypothesis, specifically suggesting that strange lights or objects sighted in the skies might be alien spacecraft. Fort also wrote about the interconnectedness of nature and synchronicity. His books seem to center around the idea that everything is connected and that strange coincidences happen for a reason.

Many of these phenomena are now collectively and conveniently referred to as Fortean phenomenon, and some have developed into their own schools of thought such as UFOs as ufology, or the reports of unconfirmed animals as cryptozoology. These new disciplines are generally not recognized by most scientists or academics.

Fort often noted that the boundaries between science and pseudoscience are unclear. The boundary lines are not very well defined and they might change over time. He also points out that whereas facts are objective, how facts are interpreted depends on who is doing the interpreting and in what context. Fort insisted that there is a strong sociological influence on what is considered acceptable scientific knowledge.

Another of Fort’s great contributions is to the humor of science. Although many of the phenomena which science rejected in his day have since been proven to be objective phenomena, Fort was more of a parodist and a humorist than a scientist. He thought that scientists took themselves far too seriously and were prone to arrogance and dogmatism. Fort used humor both for its own sake and to point out what he regarded as the weaknesses of science and scientists.

Nonetheless, Fort is considered by many as the father of modern paranormalism not only because of his interest in strange phenomena, but because of his unique attitude towards religion, spiritualism and scientific dogma.