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๐Ÿ”— Axiomatic by Greg Egan

๐Ÿ”— Novels ๐Ÿ”— Novels/Science fiction ๐Ÿ”— Novels/Short story

Axiomatic (ISBNย 0-7528-1650-0) is a 1995 collection of short science fiction stories by Greg Egan. The stories all delve into different aspects of self and identity.

The Guardian described it as "Wonderful mind-expanding stuff, and well-written too."

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๐Ÿ”— Antikythera Mechanism

๐Ÿ”— Computing ๐Ÿ”— Classical Greece and Rome ๐Ÿ”— Greece ๐Ÿ”— Astronomy ๐Ÿ”— History of Science ๐Ÿ”— Alternative Views ๐Ÿ”— Time

The Antikythera mechanism (, ) is an ancient hand powered Greek analogue computer which has also been described as the first example of such device used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.

This artefact was retrieved from the sea in 1901, and identified on 17 May 1902 as containing a gear by archaeologist Valerios Stais, among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera. The instrument is believed to have been designed and constructed by Greek scientists and has been variously dated to about 87ย BC, or between 150 and 100ย BC, or to 205ย BC, or to within a generation before the shipwreck, which has been dated to approximately 70โ€“60ย BC.

The device, housed in the remains of a 34ย cm ร—ย 18ย cm ร—ย 9ย cm (13.4ย in ร—ย 7.1ย in ร—ย 3.5ย in) wooden box, was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 14 centimetres (5.5ย in) in diameter and originally had 223 teeth.

It is a complex clockwork mechanism composed of at least 30 meshing bronze gears. A team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine.

Detailed imaging of the mechanism suggests that it had 37 gear wheels enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and even to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction.

The knowledge of this technology was lost at some point in antiquity. Similar technological works later appeared in the medieval Byzantine and Islamic worlds, but works with similar complexity did not appear again until the development of mechanical astronomical clocks in Europe in the fourteenth century. All known fragments of the Antikythera mechanism are now kept at the National Archaeological Museum in Athens, along with a number of artistic reconstructions and replicas of the mechanism to demonstrate how it may have looked and worked.

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๐Ÿ”— Wiioโ€™s laws: Communication usually fails, except by accident

๐Ÿ”— Sociology ๐Ÿ”— Finland

Wiio's laws are humoristically formulated observations about how humans communicate.

Wiio's laws are usually summarized with "Human communications usually fail except by accident", which is the main observation made by Professor Osmo Antero Wiio in 1978.

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๐Ÿ”— Phantom OS, a Russian OS where โ€œeverything is an objectโ€

๐Ÿ”— Computing ๐Ÿ”— Computing/Software ๐Ÿ”— Computing/Free and open-source software

Phantom OS is an operating system mostly made by Russian programmers. Phantom OS is based on a concept of persistent virtual memory, and is managed-code oriented. Phantom OS is one of a few OSes that are not based on classical concepts of Unix-like systems. Its primary goal is to achieve simplicity and effectiveness in both the operating system and applications at the same time.

Phantom is based on the principle that "Everything is an object", in contrast to the Unix-like approach of "Everything is a file".

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๐Ÿ”— Smeed's law

๐Ÿ”— Transport

Smeed's Law, named after R. J. Smeed, who first proposed the relationship in 1949, is a purported empirical rule relating traffic fatalities to traffic congestion as measured by the proxy of motor vehicle registrations and country population. The law proposes that increasing traffic volume (an increase in motor vehicle registrations) leads to an increase in fatalities per capita, but a decrease in fatalities per vehicle.

Smeed also predicted that the average speed of traffic in central London would always be nine miles per hour, because that is the minimum speed that people tolerate. He predicted that any intervention intended to speed traffic would only lead to more people driving at this "tolerable" speed unless there were any other disincentives against doing so.

His hypothesis in relation to road traffic safety has been refuted by several authors, who point out that fatalities per person have decreased in many countries, when the "Law" requires that they should increase as long as the number of vehicles per person continues to rise.

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๐Ÿ”— Jesus Nut

๐Ÿ”— Aviation ๐Ÿ”— Aviation/rotorcraft

Jesus nut is a slang term for the main rotor retaining nut or mast nut, which holds the main rotor to the mast of some helicopters. The related slang term Jesus pin refers to the lock pin used to secure the retaining nut. More generally, Jesus nut (or Jesus pin) has been used to refer to any component that is a single point of failure which results in catastrophic consequences.

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๐Ÿ”— Friendship Paradox

๐Ÿ”— Mathematics ๐Ÿ”— Statistics ๐Ÿ”— Sociology

The friendship paradox is the phenomenon first observed by the sociologist Scott L. Feld in 1991 that most people have fewer friends than their friends have, on average. It can be explained as a form of sampling bias in which people with greater numbers of friends have an increased likelihood of being observed among one's own friends. In contradiction to this, most people believe that they have more friends than their friends have.

The same observation can be applied more generally to social networks defined by other relations than friendship: for instance, most people's sexual partners have had (on the average) a greater number of sexual partners than they have.

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๐Ÿ”— Tony Buzan, Inventor of the โ€œMind Mapโ€, Has Died

๐Ÿ”— Biography

Anthony Peter "Tony" Buzan (; 2 June 1942 โ€“ 13 April 2019) was an English author and educational consultant.

Buzan popularised the idea of mental literacy, radiant thinking, and a technique called mind mapping, inspired by techniques used by Leonardo da Vinci, Albert Einstein, and Joseph D. Novak's "concept mapping" techniques.

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๐Ÿ”— Defenestration

๐Ÿ”— Death ๐Ÿ”— Glass

Defenestration (from Old French fenestre, inherited from Latin fenestra) is the act of throwing someone or something out of a window. The term was coined around the time of an incident in Prague Castle in the year 1618 which became the spark that started the Thirty Years' War. This was done in "good Bohemian style"; this referred to the defenestration which had occurred in Prague's City Hall almost 200 years earlier (July 1419), which also on that occasion led to war: the Hussite war. The word comes from the New Latin de- (down from) and fenestra (window or opening). Likewise, it can also refer to the condition of being thrown out of a window, as in "The Defenestration of Ermintrude Inch".

While the act of defenestration connotes the forcible or peremptory removal of an adversary, and the term is sometimes used in just that sense, it also suggests breaking the windows in the process (de- also means removal).

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๐Ÿ”— R/K selection theory

๐Ÿ”— Evolutionary biology ๐Ÿ”— Ecology

In ecology, r/K selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individual parental investment of r-strategists, or on a reduced quantity of offspring with a corresponding increased parental investment of K-strategists, varies widely, seemingly to promote success in particular environments.

The terminology of r/K-selection was coined by the ecologists Robert MacArthur and E. O. Wilson in 1967 based on their work on island biogeography; although the concept of the evolution of life history strategies has a longer history (see e.g. plant strategies).

The theory was popular in the 1970s and 1980s, when it was used as a heuristic device, but lost importance in the early 1990s, when it was criticized by several empirical studies. A life-history paradigm has replaced the r/K selection paradigm but continues to incorporate many of its important themes.

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