Have a deep view into what people are curious about.

🔗 Mathematics

In number theory, specifically the study of Diophantine approximation, the lonely runner conjecture is a conjecture about the long-term behavior of runners on a circular track. It states that ${\displaystyle n}$ runners on a track of unit length, with constant speeds all distinct from one another, will each be lonely at some time—at least ${\displaystyle 1/n}$ units away from all others.

The conjecture was first posed in 1967 by German mathematician Jörg M. Wills, in purely number-theoretic terms, and independently in 1974 by T. W. Cusick; its illustrative and now-popular formulation dates to 1998. The conjecture is known to be true for 7 runners or less, but the general case remains unsolved. Implications of the conjecture include solutions to view-obstruction problems and bounds on properties, related to chromatic numbers, of certain graphs.

🔗 Computing 🔗 Systems 🔗 Computing/Software 🔗 Systems/Systems engineering

Greenspun's tenth rule of programming is an aphorism in computer programming and especially programming language circles that states:

Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.

🔗 Spaceflight 🔗 Physics 🔗 Alternative Views 🔗 Physics/relativity

The Alcubierre drive, Alcubierre warp drive, or Alcubierre metric (referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by Mexican theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.

Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space without breaking any physical laws.

Although the metric proposed by Alcubierre is consistent with the Einstein field equations, construction of such a drive is not necessarily possible. The proposed mechanism of the Alcubierre drive implies a negative energy density and therefore requires exotic matter. So if exotic matter with the correct properties cannot exist, then the drive could not be constructed. At the close of his original article, however, Alcubierre argued (following an argument developed by physicists analyzing traversable wormholes) that the Casimir vacuum between parallel plates could fulfill the negative-energy requirement for the Alcubierre drive.

Another possible issue is that, although the Alcubierre metric is consistent with Einstein's equations, general relativity does not incorporate quantum mechanics. Some physicists have presented arguments to suggest that a theory of quantum gravity (which would incorporate both theories) would eliminate those solutions in general relativity that allow for backwards time travel (see the chronology protection conjecture) and thus make the Alcubierre drive invalid.

🔗 Literature

The Thirty-Six Dramatic Situations is a descriptive list which was first proposed by Georges Polti in 1895 to categorize every dramatic situation that might occur in a story or performance. Polti analyzed classical Greek texts, plus classical and contemporaneous French works. He also analyzed a handful of non-French authors. In his introduction, Polti claims to be continuing the work of Carlo Gozzi, who also identified 36 situations.

🔗 Computing 🔗 Computing/Computer hardware 🔗 Computing/Computer science

The replay system is a little-known subsystem within the Intel Pentium 4 processor. Its primary function is to catch operations that have been mistakenly sent for execution by the processor's scheduler. Operations caught by the replay system are then re-executed in a loop until the conditions necessary for their proper execution have been fulfilled.

🔗 Archaeology 🔗 Museums 🔗 Merseyside

The Williamson Tunnels are a series of extensive subterranean excavations, of unknown purpose, in the Edge Hill area of Liverpool, England. They are thought to have been created under the direction of tobacco merchant, landowner and philanthropist Joseph Williamson between 1810 and 1840. Although popularly described as "tunnels", the majority comprise brick or stone vaulting over excavations in the underlying sandstone. The purpose of the works remains unclear and remains a subject of heavy speculation; suggestions include commercial quarrying, a philanthropic desire to provide employment, and Williamson's own eccentric interests.

After being gradually infilled with rubble and spoil during the late 19th and early 20th centuries, they remained largely inaccessible until archaeological investigations were carried out in 1995. Since then volunteers have rediscovered and excavated an extensive network of tunnels, chambers and voids across several sites, with sections open to the public. Guided tours are available at the Williamson Tunnels Heritage Centre and the Friends Of Williamson's Tunnels, and excavation continues as volunteers continue to uncover new sections.

🔗 Mathematics

The moving sofa problem or sofa problem is a two-dimensional idealisation of real-life furniture-moving problems and asks for the rigid two-dimensional shape of largest area A that can be maneuvered through an L-shaped planar region with legs of unit width. The area A thus obtained is referred to as the sofa constant. The exact value of the sofa constant is an open problem.

🔗 Biography 🔗 Africa 🔗 Japan 🔗 Japan/History 🔗 Japan/Biography

Yasuke (variously rendered as 弥助 or 弥介, 彌助 or 彌介 in different sources) was a man of African origin who served as a retainer under the Japanese daimyō Oda Nobunaga. In 1579, Yasuke arrived in Japan in the service of Italian Jesuit missionary Alessandro Valignano, Visitor of Missions in the Indies, in India.

Yasuke is thought by some to have been the first African that Nobunaga had ever seen and he was one of the many Africans to have come with the Portuguese to Japan during the Nanban trade. He was also present during the Honnō-ji Incident, the forced suicide of Nobunaga at the hands of his samurai general Akechi Mitsuhide on 21 June 1582.

🔗 Computer science 🔗 Mathematics

In mathematical logic and computer science, homotopy type theory (HoTT ) refers to various lines of development of intuitionistic type theory, based on the interpretation of types as objects to which the intuition of (abstract) homotopy theory applies.

This includes, among other lines of work, the construction of homotopical and higher-categorical models for such type theories; the use of type theory as a logic (or internal language) for abstract homotopy theory and higher category theory; the development of mathematics within a type-theoretic foundation (including both previously existing mathematics and new mathematics that homotopical types make possible); and the formalization of each of these in computer proof assistants.

There is a large overlap between the work referred to as homotopy type theory, and as the univalent foundations project. Although neither is precisely delineated, and the terms are sometimes used interchangeably, the choice of usage also sometimes corresponds to differences in viewpoint and emphasis. As such, this article may not represent the views of all researchers in the fields equally. This kind of variability is unavoidable when a field is in rapid flux.

🔗 United States 🔗 Linguistics 🔗 Linguistics/Applied Linguistics 🔗 Writing systems 🔗 United States/Utah 🔗 English Language 🔗 Latter Day Saint movement

The Deseret alphabet ( (listen); Deseret: 𐐔𐐯𐑅𐐨𐑉𐐯𐐻 or 𐐔𐐯𐑆𐐲𐑉𐐯𐐻) is a phonemic English-language spelling reform developed between 1847 and 1854 by the board of regents of the University of Deseret under the leadership of Brigham Young, the second president of the Church of Jesus Christ of Latter-day Saints (LDS Church). George D. Watt is reported to have been the most actively involved in the development of the script,^: 159 as well as being its first serious user.^: 12

The Deseret alphabet was an outgrowth of the idealism and utopianism of Young and the early LDS Church. Young and the Mormon pioneers believed "all aspects of life" were in need of reform for the imminent millenniumand the Deseret alphabet was just one of many ways they sought to bring about a complete "transformation in society",^: 142 in anticipation of the Second Coming of Jesus. Young wrote of the reform that "it would represent every sound used in the construction of any known language; and, in fact, a step and partial return to a pure language which has been promised unto us in the latter days," the Adamic language spoken before the Tower of Babel.

In public statements, Young claimed the alphabet would replace the traditional Latin alphabet with an alternative, more phonetically accurate alphabet for the English language. This would offer immigrants an opportunity to learn to read and write English, he said, the orthography of which is often less phonetically consistent than those of many other languages.^: 65–66 Similar neographies have been attempted, the most well-known of which for English is the Shavian alphabet.

Young also prescribed the learning of Deseret to the school system, stating "It will be the means of introducing uniformity in our orthography, and the years that are now required to learn to read and spell can be devoted to other studies."

During the alphabet's heyday between 1854 and 1869, scriptural passages in newspapers, selected church records, a $5 gold coin, and occasional street signs and correspondence used the new letters. In 1868-9, after much difficulty creating suitable fonts, four books were printed: two school primers, the full Book of Mormon, and a portion of it titled the Book of Nephi.

Despite heavy and costly promotion by the early LDS Church, the alphabet never enjoyed prolonged widespread use and has been regarded by historians as a failure. However, in recent years, aided by digital typography, the Deseret Alphabet has been revived as a cultural heirloom.