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.

A prepared piano is a piano which has had its sound altered by placing objects between or on the strings or on the hammers or dampers. The idea of altering an instrument’s timbre through the use of external objects has been applied to instruments other than the piano, such as the guitar. Although it is possible to prepare an upright piano, it is far easier, and far more common, on a grand piano.

A composer using prepared piano extensively was John Cage, who is often credited with inventing the instrument. He first prepared a piano when he was commissioned to write music for Bacchanale, a dance by Syvilla Fort in 1938. For some time previously, Cage had been writing exclusively for a percussion ensemble, but the hall where Fort’s dance was to be staged had no room for a percussion group. The only instrument available was a single grand piano.

After some consideration, Cage said that he realized it was possible to place in the hands of a single pianist the equivalent of an entire percussion orchestra. With just one musician, you can really do an unlimited number of things on the inside of the piano if you have at your disposal an exploded keyboard. Cage would often quip that by preparing a piano he left it in better condition than he found it.

In Cage’s use, the preparations are typically nuts, bolts and pieces of rubber to be lodged between and entwined around the strings. Some preparations make duller, more percussive sounds than usual, while others create sonorous bell-like tones. Additionally, the individual parts of a preparation like a nut loosely screwed onto a bolt will vibrate themselves, adding their own unique sound.

By placing the preparation between two of the strings on a note which has three strings assigned to it, it is possible to change the timbre of that note by depressing the soft pedal on the piano, which moves the hammers so they strike only two strings instead of all three. Other prepared piano sounds can be reminiscent of mbiras, marimbas, bells, wood blocks, Indonesian gamelan instruments, or many other sounds less easily defined.

American composer Chris Brown created a type of prepared electric piano, the Gazamba from the shell of a Wurlitzer electric piano. American composer Eric Glick Rieman has composed extensively for prepared Fender Rhodes pianos. Ross Bolleter has taken the idea into an innovative direction, exploring the use of ruined pianos, or pianos decayed by weather and time.

A star is a massive, luminous ball of plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth. For most of its life, a star shines due to thermonuclear fusion in its core releasing energy that traverses the star’s interior and then radiates into outer space. Almost all elements heavier than hydrogen and helium were created by fusion processes in stars.

Historically, stars have been important to civilizations throughout the world. They have been part of religious practices and for celestial navigation and orientation. Many ancient astronomers believed that stars were permanently affixed to a heavenly sphere, and that they were immutable. By convention, astronomers grouped stars into constellations and used them to track the motions of the planets and the inferred position of the Sun.

The motion of the Sun against the background stars and the horizon was used to create calendars, which could be used to regulate agricultural practices. The Gregorian calendar, currently used nearly everywhere in the world, is a solar calendar based on the angle of the Earth’s rotational axis relative to the nearest star, the Sun.

The oldest accurately dated star chart appeared in Ancient Egypt. Islamic astronomers gave names to many stars which are still used today, and they invented numerous astronomical instruments which could compute the positions of the stars.

William Herschel was the first astronomer to attempt to determine the distribution of stars in the sky. During the 1780s, he performed a series of measurements in 600 directions, and counted the stars observed along each line of sight. From this he deduced that the number of stars steadily increased toward one side of the sky, in the direction of the Milky Way core. He is also noted for his discovery that some stars do not merely lie along the same line of sight, but are also physical companions that form binary star systems.

The twentieth century saw increasingly rapid advances in the scientific study of stars. The photograph became a valuable astronomical tool. It was discovered that the color of a star, and hence its temperature, could be determined by comparing the visual magnitude against the photographic magnitude. The development of the photoelectric photometer allowed very precise measurements of magnitude at multiple wavelength intervals.

Important conceptual work on the physical basis of stars occurred during the first decades of the twentieth century. Successful models were developed to explain the interiors of stars and stellar evolution. The spectra of stars were also successfully explained through advances in quantum physics. This allowed the chemical composition of the stellar atmosphere to be determined.

With the exception of supernovae, individual stars have primarily been observed in our local group of galaxies, and especially in the visible part of the Milky Way. In the local supercluster it is possible to see star clusters. The most distant stars resolved have been up to hundred million light years away. The only exception is a faint image of a large star cluster containing hundreds of thousands of stars located one billion light years away, ten times the distance of the most distant star cluster previously observed.

A gamelan is a musical ensemble from Indonesia, typically from the islands of Bali or Java, featuring a variety of instruments such as metallophones, xylophones, drums and gongs. The word comes from the Javanese word “gamel” meaning to strike or hammer, and the suffix “an”, which makes the root a collective noun.

The term refers more to the set of instruments than to the players of those instruments. A gamelan is a set of instruments as a distinct entity, built and tuned to stay together. Instruments from different gamelan are generally not interchangeable.

In Javanese mythology, the gamelan was created in AD 230. The god who ruled as king of all Java from a palace on Mount Lawu needed a signal to summon the gods, and thus invented the gong. For more complex messages, he invented two other Gongs, thus forming the basis of the original gamelan set.

The gamelan predates the Hindu-Buddhist culture that dominated Indonesia in its earliest records, and instead represents a native art form. In contrast to the Indian influence in other art forms, the only obvious Indian influence in gamelan music is in the Javanese style of singing.

In Indonesia, gamelan usually accompanies dance, puppet performances, or rituals and ceremonies. Typically players in the gamelan will be familiar with dance moves and poetry, while dancers are able to play in the ensemble. In wayang puppet performances, the puppeteer must have a thorough knowledge of gamelan, as he gives the cues for the music.

Gamelan’s role in rituals is so important that there is a Javanese saying that “It’s not official until the gong is hung.” Certain gamelans are associated with specific rituals, such as the Gamelan Sekaten, which is used in celebration of Muhammad’s birthday. In Bali, almost all religious rituals include gamelan performance. Gamelan is also used in the ceremonies of the Catholic church in Indonesia.

Certain pieces are designated for starting and ending performances or ceremonies. When a “leaving” piece is begun, the audience will know that the event is nearly finished and will begin to leave. Certain pieces are also believed to possess magic powers, and can be used to ward off evil spirits.

There is an increasing amount of gamelan outside Indonesia. There are even forms of gamelan that have originated outside Indonesia, such as American gamelan and Malay Gamelan in Malaysia.

There are also professional American gamelan ensembles. Gamelan Son of Lion is a group that focuses on newly composed music by both the members of the group and invited composers from around the world. Gamelan Kori Mas performs Balinese music on bamboo instruments in the San Francisco bay area.

Guido von List was a Viennese poet, journalist, writer, businessman, mountaineer, hiker, dramatist and playwright, but was most notable as an occultist and who is seen as one of the most important figures in Runic Revivalism in the early 20th century.

He elaborated a racial religion premised on the concept of returning to the pagan religions of the ancient Indo-Europeans. In this, he became strongly influenced by the Theosophical thought of Madame Blavatsky, which he blended with his own highly original beliefs.

His conception of the original religion of tribes was a form of sun worship, with its priests as legendary rulers. Religious instruction was imparted on two levels. The esoteric doctrine was concerned with the secret mysteries of the gnosis and reserved for the initiated elite, while the exoteric doctrine took the form of popular myths intended for the lower social classes.

List was familiar with the cyclical notion of time, which he encountered in Norse mythology and in the theosophical adaptation of the Hindu time cycles. He had already made use of cosmic rhythms in his early journalism on natural landscapes. In his later works List combined the cyclical concept of time with the dualistic and linear time scheme of western apocalyptic which counterposes a pessimism about the present world with an ultimate optimism regarding the future one.

List addresses the seeming contradiction by explaining the final redemption of the linear time frame as an exoteric parable which stands for the esoteric truth of renewal in many future cycles and incarnations. However, in the original Norse myths and Hinduism, the cycle of destruction and creation is repeated indefinitely, thus offering no possibility of ultimate salvation.

He also believed in magical powers of the old runes. In 1891 he claimed that heraldry was based on the magic of the runes. In April 1903, he had sent an article concerning an alleged proto language to the Imperial Academy of Sciences in Vienna. Its highlight was a mystical and occult interpretation of the runic alphabet. Although the article was rejected by the academy, it would later be expanded by List and become the basis for his entire ideology.

List’s system was allegedly based around the structure of a hexagonal crystal. You can shine light through a crystal at different angles and project all 18 of the Armanen runes. While the runes of the past had had sharp angles for easy carving, his were to be carefully and perfectly made so that their shape would be a reflection of the frozen light, a pattern that he had found in his runes. All of his runes could be projected by shining the light through a hexagonal crystal under certain angles. 

Karl Hans Welz states that the crystalline structure of quartz is the hexagonal system which is also one of the bases of the Runic symbolism, and that the hexagonal cross section of quartz and the fact that all of the 18 Sacred Futhork Runes are derived from the geometry of the hexagon is the basis of an enormous increase in crystal power when it is associated with Rune images.

Sweet potatoes are native to tropical areas of South America and were domesticated there at least 5000 years ago. They spread very early throughout the region, including the Caribbean. They were also known before western exploration in Polynesia. Exactly how they arrived there is a subject of ongoing research and discussion of various hypotheses involving archaeological, linguistic and genetic evidence.

It has been postulated that the centre of origin was between the Yucatan Peninsula of Mexico and the mouth of the Orinoco River in Venezuela. The cultigen had most likely been spread by local people to South America by 2500 BC. The much lower molecular diversity found in the Peru-Ecuador species suggests that this region should be considered as a secondary centre of sweet potato diversity.

Sweet potatoes are now cultivated throughout tropical and warm temperate regions wherever there is sufficient water to support their growth. The plant does not tolerate frost.

Sometimes called a yam, the sweet potato is not in the yam family, nor it closely related to the common potato. The first Europeans to taste sweet potatoes were members of the Columbus expedition in 1492. Later explorers found many varieties under an assortment of local names, but the name which stayed was the indigenous Taino name of batata. This name was later transferred to the ordinary potato, causing a confusion from which it never recovered.

They grow well in many farming conditions and have few natural enemies. Pesticides are rarely needed. They can be grown in poor soils with little fertilizer. Because they are sown by vine cuttings rather than seeds, sweet potatoes are relatively easy to plant. Because the rapidly growing vines shade out weeds, little weeding is needed and farmers can devote time to other crops. In the tropics the crop can be maintained in the ground and harvested as needed for market or home consumption.

After harvesting, the sweet potatoes are dried in the sun for 2 to 3 hours. Then they are spread out in baskets lined with newspaper and placed in a dry area where the temperature will remain 80-85 degrees F. for 10 days to 2 weeks. After this curing period, they are placed where the temperature will range from 55-60 degrees F. with a relative humidity of about 85 percent. Sweet potatoes treated this way will store for several months.

In 1992, the Center for Science in the Public Interest compared the nutritional value of sweet potatoes to other vegetables. Considering fiber content, complex carbohydrates, protein, vitamins A and C, iron, and calcium, the sweet potato ranked highest in nutritional value. According to these criteria, sweet potatoes earned 184 points, 100 points over the next on the list, the common potato.

Acoustic phonetics is a subfield of phonetics which deals with acoustic aspects of speech sounds. It investigates properties such as the mean squared amplitude of a waveform, its duration, its fundamental frequency or other properties of its frequency spectrum, and to abstract linguistic concepts like phrases and utterances.

The study of acoustic phonetics was greatly enhanced in the late 19th century by the invention of the Edison phonograph. The phonograph allowed the speech signal to be recorded and then later processed and analyzed. By replaying the same speech signal from the phonograph several times, filtering it each time with a different filter, a spectrogram or graphic image of the speech recording could be created.

A series of papers by Ludimar Hermann investigated the spectral properties of vowels and consonants using the Edison phonograph, and it was in these papers that the term formant was first introduced. Hermann also played back vowel recordings made with the Edison phonograph at different speeds in an effort to distinguish between varying theories of vowel production.

Further advances in acoustic phonetics were made possible by the development of the telephone industry. During World War II, work at the Bell Telephone Laboratories greatly facilitated the systematic study of the spectral properties of periodic and aperiodic speech sounds, vocal tract resonances and vowel formants, voice quality and prosody.

On a theoretical level, acoustic phonetics advanced greatly when it became clear that speech acoustics could be modeled in a way analogous to electrical circuits. During the early 1900s, Lord Rayleigh was among the first to recognize that the new electric theory could be used in acoustics, but it was not until 1941 that the circuit model was effectively used. In 1952, the book Preliminaries to Speech Analysis was published, tying acoustic phonetics and phonological theory together. This was followed in 1960 by Gunnar Fant’s Acoustic Theory of Speech Production, which has remained the major theoretical foundation for speech acoustic research in both the academy and industry.

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.