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๐ Rongorongo
Rongorongo (; Rapa Nui: [หษพoลoหษพoลo]) is a system of glyphs discovered in the 19th century on Easter Island that appears to be writing or proto-writing. Numerous attempts at decipherment have been made, none successfully. Although some calendrical and what might prove to be genealogical information has been identified, none of these glyphs can actually be read. If rongorongo does prove to be writing and proves to be an independent invention, it would be one of very few independent inventions of writing in human history.
Two dozen wooden objects bearing rongorongo inscriptions, some heavily weathered, burned, or otherwise damaged, were collected in the late 19th century and are now scattered in museums and private collections. None remain on Easter Island. The objects are mostly tablets shaped from irregular pieces of wood, sometimes driftwood, but include a chieftain's staff, a bird-man statuette, and two reimiro ornaments. There are also a few petroglyphs which may include short rongorongo inscriptions. Oral history suggests that only a small elite was ever literate and that the tablets were sacred.
Authentic rongorongo texts are written in alternating directions, a system called reverse boustrophedon. In a third of the tablets, the lines of text are inscribed in shallow fluting carved into the wood. The glyphs themselves are outlines of human, animal, plant, artifact and geometric forms. Many of the human and animal figures, such as glyphs 200 and 280 , have characteristic protuberances on each side of the head, possibly representing eyes.
Individual texts are conventionally known by a single uppercase letter and a name, such as Tablet C, the Mamari Tablet. The somewhat variable names may be descriptive or indicate where the object is kept, as in the Oar, the Snuffbox, the Small Santiago Tablet, and the Santiago Staff.
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- "Rongorongo" | 2020-02-08 | 80 Upvotes 17 Comments
๐ Galton Board
The bean machine, also known as the Galton Board or quincunx, is a device invented by Sir Francis Galton to demonstrate the central limit theorem, in particular that with sufficient sample size the binomial distribution approximates a normal distribution. Among its applications, it afforded insight into regression to the mean or "regression to mediocrity".
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- "Galton Board" | 2019-06-18 | 98 Upvotes 30 Comments
๐ Sensorvault
Sensorvault is an internal Google database that contains records of users' historical geo-location data.:โ1โ
It has been used by law enforcement to obtain a geo-fence warrant and to search for all devices within the vicinity of a crime, (within a geo-fenced area):โ1โ:โ1โ and after looking at those devices' movements and narrowing those devices down to potential suspects or witnesses, then asking Google for the information about the owners of those devices.:โ1โ:โ1โ
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- "Sensorvault" | 2023-10-16 | 101 Upvotes 13 Comments
๐ Free beer
Free Beer, originally known as Vores รธl - An open source beer (Danish for: Our Beer), is the first brand of beer with an "open"/"free" brand and recipe. The recipe and trademark elements are published under the Creative Commons CC BY-SA license.
The beer was created in 2004 by students at the IT University in Copenhagen together with artist collective Superflex, to illustrate how concepts of the FOSS movement might be applied outside the digital world. The "Free Beer" concept illustrates also the connection between the long tradition of freely sharing cooking recipes with the FOSS movement, which tries to establish this sharing tradition also for the "recipes" of software, the source code. The "Free beer" concept received an overall positive reception from international press and media for the political message, was presented on many exhibitions and conferences, and inspired many breweries in adopting the concept.
๐ Electret
An electret (formed of as a portmanteau of electr- from "electricity" and -et from "magnet") is a dielectric material that has a quasi-permanent electric charge or dipole polarisation. An electret generates internal and external electric fields, and is the electrostatic equivalent of a permanent magnet. Although Oliver Heaviside coined this term in 1885, materials with electret properties were already known to science and had been studied since the early 1700s. One particular example is the electrophorus, a device consisting of a slab with electret properties and a separate metal plate. The electrophorus was originally invented by Johan Carl Wilcke in Sweden and again by Alessandro Volta in Italy.
The name derives from "electron" and "magnet"; drawing analogy to the formation of a magnet by alignment of magnetic domains in a piece of iron. Historically, electrets were made by first melting a suitable dielectric material such as a polymer or wax that contains polar molecules, and then allowing it to re-solidify in a powerful electrostatic field. The polar molecules of the dielectric align themselves to the direction of the electrostatic field, producing a dipole electret with a permanent electrostatic bias. Modern electrets are usually made by embedding excess charges into a highly insulating dielectric, e.g. by means of an electron beam, corona discharge, injection from an electron gun, electric breakdown across a gap, or a dielectric barrier.
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- "Electret" | 2022-07-07 | 67 Upvotes 20 Comments
๐ Hofstadter's butterfly
In condensed matter physics, Hofstadter's butterfly describes the spectral properties of non-interacting two dimensional electrons in a magnetic field. The fractal, self-similar, nature of the spectrum was discovered in the 1976 Ph.D. work of Douglas Hofstadter and is one of the early examples of computer graphics. The name reflects the visual resemblance of the figure on the right to a swarm of butterflies flying to infinity.
The Hofstadter butterfly plays an important role in the theory of the integer quantum Hall effect, and D.J. Thouless has been awarded the Nobel prize in physics in 2016 for the discovery that the wings of the butterfly are characterized by Chern integers, the quantized Hall conductances discovered in 1980 by Klaus von Klitzing for which he has been awarded the Nobel prize in 1985. The colors in the diagram reflect the different Chern numbers.
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- "Hofstadter's butterfly" | 2014-06-20 | 41 Upvotes 10 Comments
๐ Glykon, was an ancient snake god
Glycon (Ancient Greek: ฮฮปฯฮบฯฮฝ Glรฝkลn, gen: ฮฮปฯฮบฯฮฝฮฟฯ Glรฝkลnos), also spelled Glykon, was an ancient snake god. He had a large and influential cult within the Roman Empire in the 2nd century, with contemporary satirist Lucian providing the primary literary reference to the deity. Lucian claimed Glycon was created in the mid-2nd century by the Greek prophet Alexander of Abonoteichos. Lucian was ill-disposed toward the cult, calling Alexander a false prophet and accusing the whole enterprise of being a hoax: Glycon himself was supposedly a hand puppet.
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- "Glykon, was an ancient snake god" | 2023-07-17 | 51 Upvotes 42 Comments
๐ Monge's theorem
In geometry, Monge's theorem, named after Gaspard Monge, states that for any three circles in a plane, none of which is completely inside one of the others, the intersection points of each of the three pairs of external tangent lines are collinear.
For any two circles in a plane, an external tangent is a line that is tangent to both circles but does not pass between them. There are two such external tangent lines for any two circles. Each such pair has a unique intersection point in the extended Euclidean plane. Monge's theorem states that the three such points given by the three pairs of circles always lie in a straight line. In the case of two of the circles being of equal size, the two external tangent lines are parallel. In this case Monge's theorem asserts that the other two intersection points must lie on a line parallel to those two external tangents. In other words, if the two external tangents are considered to intersect at the point at infinity, then the other two intersection points must be on a line passing through the same point at infinity, so the line between them takes the same angle as the external tangent.
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- "Monge's theorem" | 2018-07-15 | 83 Upvotes 10 Comments
๐ Cubic mile of oil
The cubic mile of oil (CMO) is a unit of energy, aiming to give the general public an understanding of large quantities of energy. It is approximately equal to 1.6ร1020 joule. It was created by Hew Crane of SRI International to aid in public understanding of global-scale energy consumption and resources.
Large scale sources of energy include wind, solar photovoltaic, solar thermal, nuclear, hydroelectric, oil, coal, natural gas, geothermal, and biomass (primarily the burning of wood). Traditionally, many different units are commonly used to measure these sources (e.g., joules, BTUs, kilowatt hours, therms) but only some of them are familiar to a global general public, and some argue that fewer are needed and a standard should be chosen. Still, these common energy units are mainly sized for everyday activities, for example a joule is the energy required to lift a small apple one metre vertically. For regional, national, and global scales, larger energy units, such as exajoule, terawatt-hour, billion barrels of oil equivalent (BBOE) and quad are used. Derived by multiplying the small common units by large powers of ten these larger units pose additional conceptual difficulties for many citizens.
Crane intended the cubic mile of oil to provide a visualizable scale for comparing the contributions of these diverse energy components as a percentage of total worldwide, energy use.
In 2005, the global economy was consuming approximately 30ย billion barrels (4.8ย billion cubic metres; 1.3ย trillion US gallons) of oil each year. Numbers of this magnitude are difficult to conceive by most people. The volume occupied by 1ย trillion US gallons (3.8ย billion cubic metres) is about 1 cubic mile (4.2ย billion cubic metres). Crane felt that a cubic mile would be an easier concept for the general public than a trillion gallons.
๐ Elephant intelligence
Elephant cognition is the study of animal cognition as present in elephants. Most contemporary ethologists view the elephant as one of the world's most intelligent animals. With a mass of just over 11ย lb (5ย kg), an elephant's brain has more mass than that of any other land animal, and although the largest whales have body masses twenty times those of a typical elephant, a whale's brain is barely twice the mass of an elephant's brain. In addition, elephants have a total of 300 billion neurons. Elephant brains are similar to humans' and many other mammals' in terms of general connectivity and functional areas, with several unique structural differences. The elephant cortex has as many neurons as a human brain, suggesting convergent evolution.
Elephants manifest a wide variety of behaviors, including those associated with grief, learning, mimicry, play, altruism, use of tools, compassion, cooperation, self-awareness, memory, and communication. Further, evidence suggests elephants may understand pointing: the ability to nonverbally communicate an object by extending a finger, or equivalent. It is thought they are equal with cetaceans and primates in this regard. Due to such claims of high intelligence and due to strong family ties of elephants, some researchers argue it is morally wrong for humans to cull them. Aristotle described the elephant as "the animal that surpasses all others in wit and mind."
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- "Elephant intelligence" | 2008-03-05 | 32 Upvotes 10 Comments