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π D. B. Cooper
D. B. Cooper is a media epithet used to refer to an unidentified man who hijacked a Boeing 727 aircraft in United States airspace between Portland, Oregon, and Seattle, Washington, on the afternoon of November 24, 1971. He extorted $200,000 in ransom (equivalent to $1,278,000 in 2020) and parachuted to an uncertain fate over southwestern Washington. The man purchased his airline ticket using the alias Dan Cooper but, because of a news miscommunication, became known in popular lore as D. B. Cooper.
The FBI maintained an active investigation for 45 years after the hijacking. Despite a case file that grew to over 60 volumes over that period, no definitive conclusions were reached regarding Cooper's true identity or fate. The crime remains the only unsolved air piracy in commercial aviation history.
Numerous theories of widely varying plausibility have been proposed over the years by investigators, reporters, and amateur enthusiasts. $5,880 of the ransom was found along the banks of the Columbia River in 1980, which triggered renewed interest but ultimately only deepened the mystery. The great majority of the ransom remains unrecovered.
The FBI officially suspended active investigation of the case in July 2016, but the agency continues to request that any physical evidence that might emerge related to the parachutes or the ransom money be submitted for analysis.
Discussed on
- "D. B. Cooper" | 2023-05-05 | 30 Upvotes 8 Comments
- "D. B. Cooper" | 2021-11-25 | 18 Upvotes 5 Comments
π Ton 618, 40B solar mass
TON 618 (short for Tonantzintla 618) is a hyperluminous, broad-absorption-line, radio-loud quasar and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40 billion Mβ.
Discussed on
- "Ton 618, 40B solar mass" | 2023-05-05 | 22 Upvotes 4 Comments
π Snobol (βStriNg Oriented and SymBOlic Languageβ)
SNOBOL ("StriNg Oriented and symBOlic Language") is a series of programming languages developed between 1962 and 1967 at AT&T Bell Laboratories by David J. Farber, Ralph E. Griswold and Ivan P. Polonsky, culminating in SNOBOL4. It was one of a number of text-string-oriented languages developed during the 1950s and 1960s; others included COMIT and TRAC.
SNOBOL4 stands apart from most programming languages of its era by having patterns as a first-class data type (i.e. a data type whose values can be manipulated in all ways permitted to any other data type in the programming language) and by providing operators for pattern concatenation and alternation. SNOBOL4 patterns are a type of object and admit various manipulations, much like later object-oriented languages such as JavaScript whose patterns are known as regular expressions. In addition SNOBOL4 strings generated during execution can be treated as programs and either interpreted or compiled and executed (as in the eval function of other languages).
SNOBOL4 was quite widely taught in larger U.S. universities in the late 1960s and early 1970s and was widely used in the 1970s and 1980s as a text manipulation language in the humanities.
In the 1980s and 1990s, its use faded as newer languages such as AWK and Perl made string manipulation by means of regular expressions fashionable. SNOBOL4 patterns subsume BNF grammars, which are equivalent to context-free grammars and more powerful than regular expressions. The "regular expressions" in current versions of AWK and Perl are in fact extensions of regular expressions in the traditional sense, but regular expressions, unlike SNOBOL4 patterns, are not recursive, which gives a distinct computational advantage to SNOBOL4 patterns. (Recursive expressions did appear in Perl 5.10, though, released in December 2007.)
The later SL5 (1977) and Icon (1978) languages were designed by Griswold to combine the backtracking of SNOBOL4 pattern matching with more standard ALGOL-like structuring.
Discussed on
- "Snobol (βStriNg Oriented and SymBOlic Languageβ)" | 2023-05-03 | 84 Upvotes 56 Comments
π Lindy Effect
The Lindy effect is a theory that the future life expectancy of some non-perishable things like a technology or an idea is proportional to their current age, so that every additional period of survival implies a longer remaining life expectancy. Where the Lindy effect applies, mortality rate decreases with time.
Discussed on
- "Lindy Effect" | 2023-05-02 | 22 Upvotes 1 Comments
- "Lindy effect" | 2017-07-30 | 225 Upvotes 64 Comments
π Banana equivalent dose
Banana equivalent dose (BED) is an informal measurement of ionizing radiation exposure, intended as a general educational example to compare a dose of radioactivity to the dose one is exposed to by eating one average-sized banana. Bananas contain naturally occurring radioactive isotopes, particularly potassium-40 (40K), one of several naturally-occurring isotopes of potassium. One BED is often correlated to 10β7 sievert (0.1 ΞΌSv); however, in practice, this dose is not cumulative, as the principal radioactive component is excreted to maintain metabolic equilibrium. The BED is only meant to inform the public about the existence of very low levels of natural radioactivity within a natural food and is not a formally adopted dose measurement.
Discussed on
- "Banana Equivalent Dose" | 2023-05-02 | 84 Upvotes 62 Comments
- "Banana equivalent dose" | 2010-06-14 | 470 Upvotes 84 Comments
π Deseret Alphabet
The Deseret alphabet ( (listen); Deseret: ππ―π π¨ππ―π» or ππ―ππ²ππ―π») 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,:β159β as well as being its first serious user.:β12β
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",:β142β 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.:β65β66β 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.
Discussed on
- "Deseret Alphabet" | 2023-05-01 | 140 Upvotes 71 Comments
π Gilbert U-238 Atomic Energy Laboratory
The Gilbert U-238 Atomic Energy Lab was a toy lab set designed to allow children to create and watch nuclear and chemical reactions using radioactive material. The Atomic Energy Lab was released by the A. C. Gilbert Company in 1950.
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- "Gilbert U-238 Atomic Energy Laboratory" | 2023-05-01 | 79 Upvotes 32 Comments
π Trap Street
In cartography, a trap street is a fictitious entry in the form of a misrepresented street on a map, often outside the area the map nominally covers, for the purpose of "trapping" potential copyright violators of the map who, if caught, would be unable to explain the inclusion of the "trap street" on their map as innocent. On maps that are not of streets, other "copyright trap" features (such as nonexistent towns, or mountains with the wrong elevations) may be inserted or altered for the same purpose.
Trap streets are often nonexistent streets; but sometimes, rather than actually depicting a street where none exists, a map will misrepresent the nature of a street in a fashion that can still be used to detect copyright violators but is less likely to interfere with navigation. For instance, a map might add nonexistent bends to a street, or depict a major street as a narrow lane, without changing its location or its connections to other streets.
Trap streets are rarely acknowledged by publishers. One known case is a popular driver's atlas for the city of Athens, Greece, which has a warning inside its front cover that potential copyright violators should beware of trap streets.
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- "Trap Street" | 2023-05-01 | 61 Upvotes 29 Comments
- "Trap Street" | 2018-08-11 | 74 Upvotes 21 Comments
- "Trap street" | 2013-01-01 | 34 Upvotes 22 Comments
π Sator Square
The Sator Square (or Rotas Square) is a word square containing a five-word Latin palindrome. The earliest form has ROTAS as the top line, but in time the version with SATOR on the top line became dominant. It is a 5X5 square made up of five 5-letter words, thus consisting of 25 letters in total. These 25 letters are all derived from 8 Latin letters: 5 consonants (S, T, R, P, N) and 3 vowels (A, E, O).
In particular, this is a square 2D palindrome, which is when a square text admits four symmetries: identity, two diagonal reflections, and 180 degree rotation. As can be seen, the text may be read top-to-bottom, bottom-to-top, left-to-right, or right-to-left; and it may be rotated 180 degrees and still be read in all those ways.
The Sator Square is the earliest dateable 2D palindrome. It was found in the ruins of Pompeii, at Herculaneum, a city buried in the ash of Mount Vesuvius in 79 AD. It consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas." Its translation has been the subject of speculation with no clear consensus; see below for details.
Other 2D Palindrome examples may be found carved on stone tablets or pressed into clay before being fired.
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- "Sator Square" | 2023-04-30 | 50 Upvotes 25 Comments
- "Sator Square" | 2019-10-30 | 38 Upvotes 13 Comments
π The Cathedral and the Bazaar
The Cathedral and the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary (abbreviated CatB) is an essay, and later a book, by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail. It examines the struggle between top-down and bottom-up design. The essay was first presented by the author at the Linux Kongress on May 27, 1997 in WΓΌrzburg (Germany) and was published as part of the book in 1999.
The illustration on the cover of the book is a 1913 painting by Liubov Popova titled Composition with Figures and belongs to the collection of the State Tretyakov Gallery. The book was released under the Open Publication License v2.0 around 1999.
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- "The Cathedral and the Bazaar" | 2023-04-29 | 24 Upvotes 1 Comments
- "The Cathedral and the Bazaar" | 2015-05-15 | 10 Upvotes 1 Comments