Have a deep view into what people are curious about.

🔗 Mathematics

The art gallery problem or museum problem is a well-studied visibility problem in computational geometry. It originates from a real-world problem of guarding an art gallery with the minimum number of guards who together can observe the whole gallery. In the geometric version of the problem, the layout of the art gallery is represented by a simple polygon and each guard is represented by a point in the polygon. A set ${\displaystyle S}$ of points is said to guard a polygon if, for every point ${\displaystyle p}$ in the polygon, there is some ${\displaystyle q\in S}$ such that the line segment between ${\displaystyle p}$ and ${\displaystyle q}$ does not leave the polygon.

🔗 Crime 🔗 Classical Greece and Rome 🔗 Greece 🔗 Egypt

Papyrus Oxyrhynchus 69 (P. Oxy. 69) is a complaint about a robbery, written in Greek. The manuscript was written on papyrus in the form of a sheet. It was discovered by Grenfell and Hunt in 1897 in Oxyrhynchus. The document was written on 21 November 190. Currently it is housed in the Haskell Oriental Institute at the University of Chicago (2061). The text was published by Grenfell and Hunt in 1898.

The beginning of the letter is lost. It is a petition to an unknown official describing the theft of some barley and asking that an investigation be carried out. The author is unknown. The measurements of the fragment are 178 by 115 mm. The description of the crime scene is quite detailed:

... they broke down a door that led into the public street and had been blocked up with bricks, probably using a log of wood as a battering-ram. They then entered the house and contented themselves with taking what was stored there, 10 artabae of barley, which they carried off by the same way. We guessed that this was removed piecemeal by the said door from the marks of a rope dragged along in that direction, and pointed out this fact to the chief of the police of that village and to the other officials.

10 artabae are equivalent to approximately 30–40 kilograms (66–88 lb) of barley.

🔗 Biology 🔗 Genetics 🔗 Computational Biology 🔗 Evolutionary biology 🔗 Human Genetic History

The last universal common ancestor (LUCA), also called the last universal ancestor (LUA), or concestor, is the most recent population of organisms from which all organisms now living on Earth have a common descent, the most recent common ancestor of all current life on Earth. (A related concept is that of progenote.) LUCA is not thought to be the first life on Earth but only one of many early organisms, all the others becoming extinct.

While there is no specific fossil evidence of LUCA, it can be studied by comparing the genomes of all modern organisms, its descendants. By this means, a 2016 study identified a set of 355 genes most likely to have been present in LUCA. (However, some of those genes could have developed later, then spread universally by horizontal gene transfer between archaea and bacteria.) The genes describe a complex life form with many co-adapted features, including transcription and translation mechanisms to convert information from DNA to RNA to proteins. The study concluded that the LUCA probably lived in the high-temperature water of deep sea vents near ocean-floor magma flows.

Studies from 2000 to 2018 have suggested an increasingly ancient time for LUCA. In 2000, estimations suggested LUCA existed 3.5 to 3.8 billion years ago in the Paleoarchean era, a few hundred million years after the earliest fossil evidence of life, for which there are several candidates ranging in age from 3.48 to 4.28 billion years ago. A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean.

Charles Darwin first proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." Later biologists have separated the problem of the origin of life from that of the LUCA.

🔗 Aviation 🔗 Crime 🔗 Lists 🔗 Novels 🔗 Correction and Detention Facilities 🔗 Popular Culture 🔗 Novels/Crime

A helicopter prison escape is made when an inmate escapes from a prison by means of a helicopter. This list includes prisoner escapes where a helicopter was used in an attempt to free prisoners from a place of internment, a prison or correctional facility.

One of the earliest instances of using a helicopter to escape a prison was the escape of Joel David Kaplan, nicknamed "Man Fan", on August 19, 1971 from the Santa Martha Acatitla in Mexico. Kaplan was a New York businessman who not only escaped the prison but eventually got out of Mexico and went on to write a book about his experience, The 10-Second Jailbreak.

France has had more recorded helicopter escape attempts than any other country, with at least 11. One of the most notable French jail breaks occurred in 1986, when the wife of bank robber Michel Vaujour studied for months to learn how to fly a helicopter. Using her newly acquired skills, she rented a white helicopter and flew low over Paris to pluck her husband off the roof of his fortress prison. Vaujour was later seriously wounded in a shootout with police, and his pilot wife was arrested.

The record for most helicopter escapes goes to convicted murderer Pascal Payet, who has used helicopters to escape from prisons in 2001, 2003, and most recently 2007.

Another multiple helicopter escapee is Vasilis Paleokostas who on February 22, 2009 escaped for the second time from the same prison. Because of this, many prisons have taken applicable precautions, such as nets or cables strung over open prison courtyards.

🔗 Philosophy 🔗 Philosophy/Aesthetics 🔗 Japan 🔗 Japan/Culture

In traditional Japanese aesthetics, wabi-sabi (侘寂) is a world view centered on the acceptance of transience and imperfection. The aesthetic is sometimes described as one of beauty that is "imperfect, impermanent, and incomplete". It is a concept derived from the Buddhist teaching of the three marks of existence (三法印, sanbōin), specifically impermanence (無常, mujō), suffering (苦, ku) and emptiness or absence of self-nature (空, kū).

Characteristics of the wabi-sabi aesthetic include asymmetry, roughness, simplicity, economy, austerity, modesty, intimacy, and appreciation of the ingenuous integrity of natural objects and processes.

🔗 Internet culture 🔗 Medicine 🔗 Psychology 🔗 Electronic music 🔗 Neuroscience 🔗 Medicine/Neurology 🔗 Medicine/Society and Medicine 🔗 Albums

Everywhere at the End of Time is the eleventh recording by the Caretaker, an alias of English electronic musician Leyland Kirby. Released between 2016 and 2019, its six studio albums use degrading loops of sampled ballroom music to portray the progression of Alzheimer's disease. Inspired by the success of An Empty Bliss Beyond This World (2011), Kirby produced Everywhere as his final major work under the alias. The albums were produced in Krakow and released over six-month periods to "give a sense of time passing". The album covers are abstract paintings by his friend Ivan Seal. The series drew comparisons to the works of composer William Basinski and electronic musician Burial; later stages were influenced by avant-gardist composer John Cage.

The series comprises six hours of music, portraying a range of emotions and characterised by noise throughout. Although the first three stages are similar to An Empty Bliss, the last three stages depart from Kirby's earlier ambient works. The albums reflect the patient's disorder and death, their feelings, and the phenomenon of terminal lucidity. To promote the series, Kirby partnered with anonymous visual artist Weirdcore to make music videos. At first, concerned about whether the series would seem pretentious, Kirby thought of not creating Everywhere at all; he spent more time producing it than any of his other releases. The album covers received attention from a French art exhibition named after the Caretaker's Everywhere, an Empty Bliss (2019), a compilation of archived songs.

As each stage was released, the series received increasingly positive reviews from critics; its length and dementia-driven concept led many reviewers to feel emotional about the complete edition. Considered to be Kirby's magnum opus, Everywhere was one of the most praised music releases of the 2010s. Caregivers of people with dementia also praised the albums for increasing empathy for patients among younger listeners, although some medics felt the series was too linear. It became an Internet phenomenon in the early 2020s, emerging in TikTok videos as a listening challenge, being transformed into a mod for the video game Friday Night Funkin' (2020), and appearing in internet memes.

🔗 Astronomy

The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe; Shapley believed that distant nebulae were relatively small and lay within the outskirts of Earth's home galaxy, while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant.

The two scientists first presented independent technical papers about "The Scale of the Universe" during the day and then took part in a joint discussion that evening. Much of the lore of the Great Debate grew out of two papers published by Shapley and by Curtis in the May 1921 issue of the Bulletin of the National Research Council. The published papers each included counter arguments to the position advocated by the other scientist at the 1920 meeting.

In the aftermath of the public debate, scientists have been able to verify individual pieces of evidence from both astronomers, but on the main point of the existence of other galaxies, Curtis has been proven correct.

🔗 Philosophy 🔗 Psychology 🔗 Philosophy/Social and political philosophy 🔗 Sociology

In social psychology, social loafing is the phenomenon of a person exerting less effort to achieve a goal when he or she works in a group than when working alone and is seen as one of the main reasons groups are sometimes less productive than the combined performance of their members working as individuals. Research on social loafing began with rope pulling experiments by Ringelmann, who found that members of a group tended to exert less effort in pulling a rope than did individuals alone. In more recent research, studies involving modern technology, such as online and distributed groups, have also shown clear evidence of social loafing. Many of the causes of social loafing stem from individual members feeling their individual effort will not matter to the group.

The French professor of agricultural engineering called Max Ringelman demonstrated what “social loafing” was in the 1890s. Ringelman, who was also considered one of the founders of social psychology, made people pull on ropes separately and in groups, and he measured and compared how hard they pulled. After collecting the results he realized that members of a group tended to exert less effort in pulling a rope than did individuals alone. In more recent research, studies involving modern technology, such as online and distributed groups, have also shown clear evidence of social loafing. Many of the causes of social loafing stem from individual members feeling that his or her effort will not matter to the group. This is seen as one of the main reasons groups are sometimes less productive than the combined performance of their members working as individuals, but should be distinguished from the accidental coordination problems that groups sometimes experience.

Several studies found, a lack of an understanding of individual contributions, unchallenging tasks given to the individual, low personal satisfaction from the task, and a lack of a united group to be the most prevalent motivational origins of social loafing. Theories investigating why social loafing occurs range from a group member feeling their contribution will not be noticed to a group member realizing their efforts are not necessary. In a work setting, most managers agree if a task is new or complex employees should work alone. While tasks that are well known and have room for individual effort are better when done in groups.

In order to diminish social loafing from a group, several strategies could be put forward. Social loafing primarily happens when an individual unconscious or conscious exerts less effort due to a decrease in social awareness. In order to counteract the likelihood of this happening, Miguel Herraez, conducted a study on students where he used accountability and cooperation when unequal participation is found. The students were encouraged to do provide equal participation in the work and to point out sources of conflict that could arise. The conclusion of the study found that providing support to the group members lacking in commitment and creating options for independence among group members lowered social loafing. The support for the weaker students improves their standing while also benefiting the other students.

Social loafing should be distinguished from the accidental coordination problems that groups sometimes experience.

🔗 Mathematics 🔗 Physics

A topological quantum computer is a theoretical quantum computer that employs two-dimensional quasiparticles called anyons, whose world lines pass around one another to form braids in a three-dimensional spacetime (i.e., one temporal plus two spatial dimensions). These braids form the logic gates that make up the computer. The advantage of a quantum computer based on quantum braids over using trapped quantum particles is that the former is much more stable. Small, cumulative perturbations can cause quantum states to decohere and introduce errors in the computation, but such small perturbations do not change the braids' topological properties. This is like the effort required to cut a string and reattach the ends to form a different braid, as opposed to a ball (representing an ordinary quantum particle in four-dimensional spacetime) bumping into a wall. Alexei Kitaev proposed topological quantum computation in 1997. While the elements of a topological quantum computer originate in a purely mathematical realm, experiments in fractional quantum Hall systems indicate these elements may be created in the real world using semiconductors made of gallium arsenide at a temperature of near absolute zero and subjected to strong magnetic fields.

🔗 Technology 🔗 Physics 🔗 Radio 🔗 Astronomy 🔗 Engineering

In engineering, the terahertz gap is a frequency band in the terahertz region of the electromagnetic spectrum between radio waves and infrared light for which practical technologies for generating and detecting the radiation do not exist. It is defined as 0.1 to 10 THz (wavelengths of 3 mm to 30 µm). Currently, at frequencies within this range, useful power generation and receiver technologies are inefficient and unfeasible.

Mass production of devices in this range and operation at room temperature (at which energy k·T is equal to the energy of a photon with a frequency of 6.2 THz) are mostly impractical. This leaves a gap between mature microwave technologies in the highest frequencies of the radio spectrum and the well developed optical engineering of infrared detectors in their lowest frequencies. This radiation is mostly used in small-scale, specialized applications such as submillimetre astronomy. Research that attempts to resolve this issue has been conducted since the late 20th century.