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๐ Plato: Allegory of the Cave
The Allegory of the Cave, or Plato's Cave, is an allegory presented by the Greek philosopher Plato in his work Republic (514aโ520a) to compare "the effect of education (ฯฮฑฮนฮดฮตฮฏฮฑ) and the lack of it on our nature". It is written as a dialogue between Plato's brother Glaucon and his mentor Socrates, narrated by the latter. The allegory is presented after the analogy of the sun (508bโ509c) and the analogy of the divided line (509dโ511e).
In the allegory "The Cave", Plato describes a group of people who have lived chained to the wall of a cave all their lives, facing a blank wall. The people watch shadows projected on the wall from objects passing in front of a fire behind them and give names to these shadows. The shadows are the prisoners' reality, but are not accurate representations of the real world. The shadows represent the fragment of reality that we can normally perceive through our senses, while the objects under the sun represent the true forms of objects that we can only perceive through reason. Three higher levels exist: the natural sciences; mathematics, geometry, and deductive logic; and the theory of forms.
Socrates explains how the philosopher is like a prisoner who is freed from the cave and comes to understand that the shadows on the wall are actually not the direct source of the images seen. A philosopher aims to understand and perceive the higher levels of reality. However, the other inmates of the cave do not even desire to leave their prison, for they know no better life.
Socrates remarks that this allegory can be paired with previous writings, namely the analogy of the sun and the analogy of the divided line.
๐ Shanti Devi
Shanti Devi (11 December 1926 โ 27 December 1987) was an Indian woman who claimed to remember her past life, and became the subject of reincarnation research. A commission set up by the Indian political leader Mahatma Gandhi supported her claim, while another report by researcher Bal Chand Nahata disputed it. Subsequently, several other researchers interviewed her, and published articles and books about her.
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- "Shanti Devi" | 2014-05-26 | 27 Upvotes 7 Comments
๐ Rescue of Roger Mallinson and Roger Chapman
The rescue of Roger Mallinson and Roger Chapman occurred between 29 August and 1 September 1973 after their Vickers Oceanics small submersible Pisces III was trapped on the seabed at a depth of 1,575ย ft (480ย m), 150ย mi (240ย km) off Ireland in the Celtic Sea. The 76-hour multinational rescue effort resulted in the deepest sub rescue in history.
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- "Rescue of Roger Mallinson and Roger Chapman" | 2021-09-04 | 31 Upvotes 1 Comments
๐ Bamboo-Copter
The bamboo-copter, also known as the bamboo dragonfly or Chinese top (Chinese zhuqingting (็ซน่ป่), Japanese taketonbo ็ซน่ป่), is a toy helicopter rotor that flies up when its shaft is rapidly spun. This helicopter-like top originated in Jin dynasty China around 320 AD, and was the object of early experiments by English engineer George Cayley, the inventor of modern aeronautics.
In China, the earliest known flying toys consisted of feathers at the end of a stick, which was rapidly spun between the hands and released into flight. "While the Chinese top was no more than a toy, it is perhaps the first tangible device of what we may understand as a helicopter."
The Jin dynasty Daoist philosopher Ge Hong's (c. 317) book Baopuzi (ๆฑๆจธๅญ "Master Who Embraces Simplicity") mentioned a flying vehicle in what Joseph Needham calls "truly an astonishing passage".
Some have made flying cars [feiche ้ฃ่ป] with wood from the inner part of the jujube tree, using ox-leather (straps) fastened to returning blades so as to set the machine in motion [huan jian yi yin chiji ็ฐๅไปฅๅผๅ ถๆฉ]. Others have had the idea of making five snakes, six dragons and three oxen, to meet the "hard wind" [gangfeng ็ฝก้ขจ] and ride on it, not stopping until they have risen to a height of forty li. That region is called [Taiqing ๅคชๆธ ] (the purest of empty space). There the [qi] is extremely hard, so much so that it can overcome (the strength of) human beings. As the Teacher says: "The kite (bird) flies higher and higher spirally, and then only needs to stretch its two wings, beating the air no more, in order to go forward by itself. This is because it starts gliding (lit. riding) on the 'hard wind' [gangqi ็ฝก็]. Take dragons, for example; when they first rise they go up using the clouds as steps, and after they have attained a height of forty li then they rush forward effortlessly (lit. automatically) (gliding)." This account comes from the adepts [xianren ไปไบบ], and is handed down to ordinary people, but they are not likely to understand it.
Needham concludes that Ge Hong was describing helicopter tops because "'returning (or revolving) blades' can hardly mean anything else, especially in close association with a belt or strap"; and suggests that "snakes", "dragons", and "oxen" refer to shapes of man-lifting kites. Other scholars interpret this Baopuzi passage mythologically instead of literally, based on its context's mentioning fantastic flights through chengqiao (ไน่นป "riding on tiptoe/stilts") and xian (ไป "immortal; adept") techniques. For instance, "If you can ride the arches of your feet, you will be able to wander anywhere in the world without hindrance from mountains or rivers โฆ Whoever takes the correct amulet and gives serious thought to the process may travel a thousand miles by concentrating his thoughts for one double hour." Compare this translation.
Some build a flying vehicle from the pith of the jujube tree and have it drawn by a sword with a thong of buffalo hide at the end of its grip. Others let their thoughts dwell on the preparation of a joint rectangle from five serpents, six dragons, and three buffaloes, and mount in this for forty miles to the region known as Paradise.
This Chinese helicopter toy was introduced into Europe and "made its earliest appearances in Renaissance European paintings and in the drawings of Leonardo da Vinci." The toy helicopter appears in a c. 1460 French picture of the Madonna and Child at the Musรฉe du Palais de Tesseโ in Mans depicting the Child holding a toy copter sitting in Maryโs lap next to St Benรดit (unknown artist), and in a 16th-century stained glass panel at the Victoria and Albert Museum in London. A picture from c. 1560 by Pieter Breughel the Elder at the Kunsthistorisches Museum in Vienna, Children's Games, depicts a helicopter top with three airscrews.
"The helicopter top in China led to nothing but amusement and pleasure, but fourteen hundred years later it was to be one of the key elements in the birth of modern aeronautics in the West." Early Western scientists developed flying machines based upon the original Chinese model. The Russian polymath Mikhail Lomonosov developed a spring-driven coaxial rotor in 1743, and the French naturalist Christian de Launoy created a bow drill device with contra-rotating feather propellers.
In 1792, George Cayley began experimenting with helicopter tops, which he later called "rotary wafts" or "elevating fliers". His landmark (1809) article "On Aerial Navigation" pictured and described a flying model with two propellers (constructed from corks and feathers) powered by a whalebone bow drill. "In 1835 Cayley remarked that while the original toy would rise no more than about 20 or 25 feet (6 or 7.5 metres), his improved models would 'mount upward of 90 ft (27 metres) into the air'. This then was the direct ancestor of the helicopter rotor and the aircraft propeller."
Discussing the history of Chinese inventiveness, the British scientist, sinologist, and historian Joseph Needham wrote, "Some inventions seem to have arisen merely from a whimsical curiosity, such as the 'hot air balloons' made from eggshells which did not lead to any aeronautical use or aerodynamic discoveries, or the zoetrope which did not lead onto the kinematograph, or the helicopter top which did not lead to the helicopter."
๐ Perpetual Stew
A perpetual stew, also known as hunter's pot or hunter's stew, is a pot into which whatever one can find is placed and cooked. The pot is never or rarely emptied all the way, and ingredients and liquid are replenished as necessary. The concept is often a common element in descriptions of medieval inns. Foods prepared in a perpetual stew have been described as being flavorful due to the manner in which the foodstuffs blend together, in which the flavor may improve with age.
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- "Perpetual Stew" | 2025-02-06 | 53 Upvotes 63 Comments
- "Perpetual Stew" | 2024-03-27 | 14 Upvotes 5 Comments
- "Perpetual Stew" | 2022-03-13 | 18 Upvotes 2 Comments
- "Perpetual Stew" | 2019-08-16 | 13 Upvotes 7 Comments
๐ 3-6-3 Rule
The term 3-6-3 Rule describes how the United States retail banking industry operated from the 1950s to the 1980s. The name 3-6-3 refers to the impression that bankers had a stable, comfortable existence by paying 3 percent interest on deposits, lending money out at 6 percent, and being able to "tee off at the golf course by 3 p.m."
The implication was that the banks were less competitive during that period than in subsequent years due to tight regulations that limited the formation and location of banks as well as restrictions on interest rates that could be charged or paid. As a result, bankers had "power and prestigeย ... while profits were steady and certain". These regulations were loosened in the 1980s.
Richmond Federal Reserve senior economist John R. Walter argues that, although there is evidence that restrictions on banks before the 1980s did limit the competitiveness of banking markets and thereby granted some banks monopoly power, "the regulatory restrictions probably had a limited effect on competition" during the time in question. Chicago Federal Reserve researchers Robert DeYoung and Tara Rice argue that, "Like most good jokes, the 3-6-3 rule mixes a grain of truth with a highly simplified view of reality."
The rule has been noted positively following the late-2000s financial crisis as a preferable way for banks to operate following the bailout of major banks.
Australia's banking system, which was deregulated in the 1990s in a manner similar to that in the U.S., also came to be characterized in the same way as did the United Kingdom's.
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- "3-6-3 Rule" | 2021-08-25 | 14 Upvotes 1 Comments
๐ WarpOS is a multitasking kernel for the PowerPC (PPC) architecture
WarpOS is a multitasking kernel for the PowerPC (PPC) architecture central processing unit (CPU) developed by Haage & Partner for the Amiga computer platform in the late 1990s and early 2000s. It runs on PowerUP accelerator boards developed by phase5 which contains both a Motorola 68000 series CPU and a PowerPC CPU with shared address space. WarpOS runs alongside the 68k-based AmigaOS, which can use the PowerPC as a coprocessor. Despite its name, it is not an operating system (OS), but a kernel; it supplies a limited set of functions similar to those in AmigaOS for using the PowerPC. When released, its original name was WarpUP, but was changed to reflect its greater feature set, and possibly to avoid comparison with its competitor, PowerUP.
It was developed by Sam Jordan using 680x0 and PowerPC assembly language.[8] It was distributed free of charge.
๐ Hiding Nobel prizes in plain sight
Aqua regia (; from Latin, lit. "regal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals, gold and platinum, though not all metals.
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- "Hiding Nobel prizes in plain sight" | 2011-03-01 | 220 Upvotes 52 Comments
๐ One red paperclip
One red paperclip is a website created by Canadian blogger Kyle MacDonald, who bartered his way from a single red paperclip to a house in a series of fourteen online trades over the course of a year. MacDonald was inspired by the childhood game Bigger, Better. His site received a considerable amount of notice for tracking the transactions. "A lot of people have been asking how I've stirred up so much publicity around the project, and my simple answer is: 'I have no idea'", he told the BBC.
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- "One red paperclip" | 2020-12-25 | 93 Upvotes 41 Comments
- "One red paperclip" | 2018-04-19 | 14 Upvotes 4 Comments
๐ Physiognomy
Physiognomy (from the Greek ฯฯฯฮนฯ, 'physis', meaning "nature", and 'gnomon', meaning "judge" or "interpreter") is the practice of assessing a person's character or personality from their outer appearanceโespecially the face. The term can also refer to the general appearance of a person, object, or terrain without reference to its implied characteristicsโas in the physiognomy of an individual plant (see plant life-form) or of a plant community (see vegetation).
Physiognomy as a practice meets the contemporary definition of pseudoscience and it is so regarded among academic circles because of its unsupported claims; popular belief in the practice of physiognomy is nonetheless still widespread and modern advances in artificial intelligence have sparked renewed interest in the field of study. The practice was well-accepted by ancient Greek philosophers, but fell into disrepute in the Middle Ages while practised by vagabonds and mountebanks. It revived and was popularised by Johann Kaspar Lavater, before falling from favor in the late 19th century. Physiognomy in the 19th century is particularly noted as a basis for scientific racism. Physiognomy as it is understood today is a subject of renewed scientific interest, especially as it relates to machine learning and facial recognition technologyThe main interest for scientists today are the risks, including privacy concerns, of physiognomy in the context of facial recognition algorithms.
Physiognomy is sometimes referred to as 'anthroposcopy', a term originating in the 19th century.