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๐ Illegal prime
An illegal prime is a prime number that represents information whose possession or distribution is forbidden in some legal jurisdictions. One of the first illegal primes was found in 2001. When interpreted in a particular way, it describes a computer program that bypasses the digital rights management scheme used on DVDs. Distribution of such a program in the United States is illegal under the Digital Millennium Copyright Act. An illegal prime is a kind of illegal number.
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- "Illegal Prime Numbers" | 2021-04-12 | 218 Upvotes 107 Comments
- "Illegal prime" | 2018-04-27 | 267 Upvotes 192 Comments
- "Illegal prime" | 2016-11-22 | 39 Upvotes 26 Comments
- "Illegal prime number" | 2014-07-30 | 59 Upvotes 30 Comments
- "Illegal Prime Numbers" | 2013-10-17 | 178 Upvotes 58 Comments
- "Illegal prime" | 2010-01-11 | 152 Upvotes 76 Comments
๐ Launch loop
A launch loop or Lofstrom loop is a proposed system for launching objects into orbit using a moving cable-like system situated inside a sheath attached to the Earth at two ends and suspended above the atmosphere in the middle. The design concept was published by Keith Lofstrom and describes an active structure maglev cable transport system that would be around 2,000ย km (1,240ย mi) long and maintained at an altitude of up to 80ย km (50ย mi). A launch loop would be held up at this altitude by the momentum of a belt that circulates around the structure. This circulation, in effect, transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.
Launch loops are intended to achieve non-rocket spacelaunch of vehicles weighing 5 metric tons by electromagnetically accelerating them so that they are projected into Earth orbit or even beyond. This would be achieved by the flat part of the cable which forms an acceleration track above the atmosphere.
The system is designed to be suitable for launching humans for space tourism, space exploration and space colonization, and provides a relatively low 3g acceleration.
Discussed on
- "Launch loop" | 2018-07-26 | 116 Upvotes 49 Comments
- "The Lofstrom Loop" | 2015-11-30 | 30 Upvotes 19 Comments
๐ Vantablack
Vantablack is a material developed by Surrey NanoSystems in the United Kingdom and is one of the darkest substances known, absorbing up to 99.965% of visible light (at 663 nm if the light is perpendicular to the material).
The name is a compound of the acronym VANTA (vertically aligned nanotube arrays) and the color black.
Discussed on
- "Vantablack, one of the darkest substances known" | 2019-02-07 | 12 Upvotes 4 Comments
๐ Avoidance Speech
Avoidance speech is a group of sociolinguistic phenomena in which a special restricted speech style must be used in the presence of or in reference to certain relatives. Avoidance speech is found in many Australian Aboriginal languages and Austronesian languages as well as some North American languages, Highland East Cushitic languages and Southern Bantu languages. Chinese naming taboo prohibits speaking and writing syllables or characters that appear in the names of esteemed people, such as emperors, parents, and ancestors.
Avoidance speech styles tend to have the same phonology and grammar as the standard language they are a part of. The lexicon, however, tends to be smaller than in normal speech since the styles are only used for limited communication.
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- "Avoidance Speech" | 2023-04-07 | 93 Upvotes 93 Comments
๐ Wigner's Friend
Wigner's friend is a thought experiment in theoretical quantum physics, first conceived by the physicist Eugene Wigner in 1961., and developed into a thought experiment by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer W observes another observer F who performs a quantum measurement on a physical system. The two observers then formulate a statement about the physical system's state after the measurement according to the laws of quantum theory. However, in most of the interpretations of quantum theory, the resulting statements of the two observers contradict each other. This reflects a seeming incompatibility of two laws in quantum theory: the deterministic and continuous time evolution of the state of a closed system and the probabilistic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrรถdinger's cat paradox.
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- "Wigner's Friend" | 2019-07-06 | 35 Upvotes 13 Comments
๐ Nicolas Bourbaki: The Greatest Mathematician That Never Existed
Nicolas Bourbaki (French pronunciation:ย โ[nikษla buสbaki]) is the collective pseudonym of a group of mathematicians, predominantly French alumni of the รcole normale supรฉrieure (ENS). Founded in 1934โ1935, the Bourbaki group originally intended to prepare a new textbook in analysis. Over time the project became much more ambitious, growing into a large series of textbooks published under the Bourbaki name, meant to treat modern pure mathematics. The series is known collectively as the รlรฉments de mathรฉmatique (Elements of Mathematics), the group's central work. Topics treated in the series include set theory, abstract algebra, topology, analysis, Lie groups and Lie algebras.
Bourbaki was founded in response to the effects of the First World War which caused the death of a generation of French mathematicians; as a result, young university instructors were forced to use dated texts. While teaching at the University of Strasbourg, Henri Cartan complained to his colleague Andrรฉ Weil of the inadequacy of available course material, which prompted Weil to propose a meeting with others in Paris to collectively write a modern analysis textbook. The group's core founders were Cartan, Claude Chevalley, Jean Delsarte, Jean Dieudonnรฉ and Weil; others participated briefly during the group's early years, and membership has changed gradually over time. Although former members openly discuss their past involvement with the group, Bourbaki has a custom of keeping its current membership secret.
The group's namesake derives from the 19th century French general Charles-Denis Bourbaki, who had a career of successful military campaigns before suffering a dramatic loss in the Franco-Prussian War. The name was therefore familiar to early 20th century French students. Weil remembered an ENS student prank in which an upperclassman posed as a professor and presented a "theorem of Bourbaki"; the name was later adopted.
The Bourbaki group holds regular private conferences for the purpose of drafting and expanding the รlรฉments. Topics are assigned to subcommittees, drafts are debated, and unanimous agreement is required before a text is deemed fit for publication. Although slow and labor-intensive, the process results in a work which meets the group's standards for rigour and generality. The group is also associated with the Sรฉminaire Bourbaki, a regular series of lectures presented by members and non-members of the group, also published and disseminated as written documents. Bourbaki maintains an office at the ENS.
Nicolas Bourbaki was influential in 20th century mathematics, particularly during the middle of the century when volumes of the รlรฉments appeared frequently. The group is noted among mathematicians for its rigorous presentation and for introducing the notion of a mathematical structure, an idea related to the broader, interdisciplinary concept of structuralism. Bourbaki's work informed the New Math, a trend in elementary math education during the 1960s. Although the group remains active, its influence is considered to have declined due to infrequent publication of new volumes of the รlรฉments. However the collective's most recent publication appeared in 2016, treating algebraic topology.
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- "Nicolas Bourbaki" | 2024-03-14 | 64 Upvotes 49 Comments
- "Nicolas Bourbaki: The Greatest Mathematician That Never Existed" | 2020-07-20 | 19 Upvotes 5 Comments
๐ Fundamental theorem of software engineering
The fundamental theorem of software engineering (FTSE) is a term originated by Andrew Koenig to describe a remark by Butler Lampson attributed to the late David J. Wheeler:
"We can solve any problem by introducing an extra level of indirection."
The theorem does not describe an actual theorem that can be proven; rather, it is a general principle for managing complexity through abstraction.
The theorem is often expanded by the humorous clause "โฆexcept for the problem of too many levels of indirection," referring to the fact that too many abstractions may create intrinsic complexity issues of their own. For example, the use of protocol layering in computer networks, which today is ubiquitous, has been criticized in ways that are typical of more general disadvantages of abstraction. Here, the adding of extra levels of indirection may cause higher layers to duplicate the functionality of lower layers, leading to inefficiency, and functionality at one layer may need data present only at another layer, which fundamentally violates the goal of separation into different layers.
๐ Alt-Right Pipeline
The alt-right pipeline (also called the alt-right rabbit hole) is a conceptual model regarding internet radicalization toward the alt-right movement. It describes a phenomenon in which consuming provocative right-wing political content, such as antifeminist or anti-SJW ideas, gradually increases exposure to the alt-right or similar far-right politics. It posits that this interaction takes place due to the interconnected nature of political commentators and online communities, allowing members of one audience or community to discover more extreme groups. This process is most commonly associated with and has been documented on the video platform YouTube, is also largely faceted by the method in which algorithms on various social media platforms function through the process recommending content that is similar to what users engage with, but can quickly lead users down rabbit-holes.
Many political movements have been associated with the pipeline concept. The intellectual dark web, libertarianism, the men's rights movement, and the alt-lite movement have all been identified as possibly introducing audiences to alt-right ideas. BreadTube has similarly been identified as introducing audiences to far-left politics, though it has been less effective. Audiences that seek out and are willing to accept extreme content in this fashion typically consist of young men, commonly those that experience significant loneliness and seek belonging or meaning. In an attempt to find community and belonging, message boards that are often proliferated with hard right social commentary, such as 4chan and 8chan, have been well documented in their importance in the radicalization process.
The alt-right pipeline may be a contributing factor to domestic terrorism. Many social media platforms have acknowledged this path of radicalization and have taken measures to prevent it, including the removal of extremist figures and rules against hate speech and misinformation.
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- "Alt-Right Pipeline" | 2023-04-23 | 32 Upvotes 50 Comments
๐ Lake Agassiz
Lake Agassiz was a very large glacial lake in central North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined though its mean depth was not as great as that of many major lakes today.
First postulated in 1823 by William H. Keating, it was named by Warren Upham in 1879 after Louis Agassiz, when Upham recognized that the lake was formed by glacial action.
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- "Lake Agassiz" | 2020-05-05 | 53 Upvotes 21 Comments
๐ The entire 1941 Japanese film Kanzashi can be watched on its Wikipedia page
Ornamental Hairpin (็ฐช, Kanzashi) is a 1941 Japanese comedy-drama film written and directed by Hiroshi Shimizu. It is based on the short story Yottsu no yubune (ๅใคใฎๆนฏๆงฝ, lit. "The four bathtubs") by Masuji Ibuse.
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- "The entire 1941 Japanese film Kanzashi can be watched on its Wikipedia page" | 2025-05-02 | 13 Upvotes 1 Comments