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๐Ÿ”— Freeman Dyson Has Died

๐Ÿ”— Biography ๐Ÿ”— Mathematics ๐Ÿ”— Physics ๐Ÿ”— Biography/science and academia ๐Ÿ”— Robotics ๐Ÿ”— United Kingdom ๐Ÿ”— Physics/Biographies ๐Ÿ”— Christianity

Freeman John Dyson (15 December 1923ย โ€“ 28 February 2020) was an English-born American theoretical physicist and mathematician known for his work in quantum electrodynamics, solid-state physics, astronomy and nuclear engineering. He was professor emeritus in the Institute for Advanced Study in Princeton, a member of the Board of Visitors of Ralston College and a member of the Board of Sponsors of the Bulletin of the Atomic Scientists.

Dyson originated several concepts that bear his name, such as Dyson's transform, a fundamental technique in additive number theory, which he developed as part of his proof of Mann's theorem; the Dyson tree, a hypothetical genetically-engineered plant capable of growing in a comet; the Dyson series, a perturbative series where each term is represented by Feynman diagrams; the Dyson sphere, a thought experiment that attempts to explain how a space-faring civilization would meet its energy requirements with a hypothetical megastructure that completely encompasses a star and captures a large percentage of its power output; and Dyson's eternal intelligence, a means by which an immortal society of intelligent beings in an open universe could escape the prospect of the heat death of the universe by extending subjective time to infinity while expending only a finite amount of energy.

Dyson believed global warming is caused merely by increased carbon dioxide but that some of the effects of this are favourable and not taken into account by climate scientists, such as increased agricultural yield. He was skeptical about the simulation models used to predict climate change, arguing that political efforts to reduce causes of climate change distract from other global problems that should take priority. He also signed the World Climate Declaration that there "is no Climate Emergency".

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๐Ÿ”— Hurrian songs

๐Ÿ”— Syria

The Hurrian songs are a collection of music inscribed in cuneiform on clay tablets excavated from the ancient Amorite-Canaanite city of Ugarit, a headland in northern Syria, which date to approximately 1400 BCE. One of these tablets, which is nearly complete, contains the Hurrian hymn to Nikkal (also known as the Hurrian cult hymn or A Zaluzi to the Gods, or simply h.6), making it the oldest surviving substantially complete work of notated music in the world. While the composers' names of some of the fragmentary pieces are known, h.6 is an anonymous work.

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๐Ÿ”— Cagot: a persecuted and despised minority found in the west of France

๐Ÿ”— France ๐Ÿ”— Basque

The Cagots (pronouncedย [ka.ษกo]) were a persecuted minority found in the west of France and northern Spain: the Navarrese Pyrenees, Basque provinces, Bรฉarn, Aragรณn, Gascony and Brittany. Their name differed by province and the local language: Cagots, Gรฉzitains, Gahets, and Gafets in Gascony; Agotes, Agotak, and Gafos in Basque country; Capots in Anjou and Languedoc; and Cacons, Cahets, Caqueux, and Caquins in Brittany. Evidence of the group exists back as far as AD 1000.

Cagots were shunned and hated; while restrictions varied by time and place, they were typically required to live in separate quarters in towns, called cagoteries, which were often on the far outskirts of the villages. Cagots were excluded from all political and social rights. They were not allowed to marry non-Cagots, enter taverns, hold cabarets, use public fountains, sell food or wine, touch food in the market, work with livestock, or enter mills. They were allowed to enter a church only by a special door and, during the service, a rail separated them from the other worshippers. Either they were altogether forbidden to partake of the sacrament, or the Eucharist was given to them on the end of a wooden spoon, while a holy water stoup was reserved for their exclusive use. They were compelled to wear a distinctive dress to which, in some places, was attached the foot of a goose or duck (whence they were sometimes called "Canards"). So pestilential was their touch considered that it was a crime for them to walk the common road barefooted or to drink from the same cup as non-Cagots. The Cagots were often restricted to the trades of carpenter, butcher, and rope-maker.

The Cagots were not an ethnic nor a religious group. They spoke the same language as the people in an area and generally kept the same religion as well. Their only distinguishing feature was their descent from families long identified as Cagots. Few consistent reasons were given as to why they were hated; accusations varied from Cagots being cretins, lepers, heretics, cannibals, to simply being intrinsically evil. The Cagots did have a culture of their own, but very little of it was written down or preserved; as a result, almost everything that is known about them relates to their persecution. The repression lasted through the Middle Ages, Renaissance, and Industrial Revolution, with the prejudice fading only in the 19th and 20th centuries.

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๐Ÿ”— Micromort

๐Ÿ”— Death ๐Ÿ”— Statistics

A micromort (from micro- and mortality) is a unit of risk defined as one-in-a-million chance of death. Micromorts can be used to measure riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus a micromort is the microprobability of death. The micromort concept was introduced by Ronald A. Howard who pioneered the modern practice of decision analysis.

Micromorts for future activities can only be rough assessments as specific circumstances will always have an impact. However past historical rates of events can be used to provide a ball park, average figure.

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๐Ÿ”— Gรถdel's Loophole

๐Ÿ”— United States/U.S. Government ๐Ÿ”— United States ๐Ÿ”— Biography ๐Ÿ”— Philosophy ๐Ÿ”— Philosophy/Logic ๐Ÿ”— Biography/science and academia ๐Ÿ”— Philosophy/Contemporary philosophy ๐Ÿ”— Philosophy/Philosophers ๐Ÿ”— United States/U.S. history ๐Ÿ”— Project-independent assessment

Gรถdel's Loophole is a "inner contradiction" in the Constitution of the United States which Austrian-German-American logician, mathematician, and analytic philosopher Kurt Gรถdel claimed to have discovered in 1947. The flaw would have allowed the American democracy to be legally turned into a dictatorship. Gรถdel told his friend Oskar Morgenstern about the existence of the flaw and Morgenstern told Albert Einstein about it at the time, but Morgenstern, in his recollection of the incident in 1971, never mentioned the exact problem as Gรถdel saw it. This has led to speculation about the precise nature of what has come to be called "Gรถdel's Loophole". It has been called "one of the great unsolved problems of constitutional law."

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๐Ÿ”— An-225

๐Ÿ”— Aviation ๐Ÿ”— Soviet Union ๐Ÿ”— Russia ๐Ÿ”— Russia/technology and engineering in Russia ๐Ÿ”— Aviation/aircraft ๐Ÿ”— Ukraine

The Antonov An-225 Mriya (Ukrainian: ะะฝั‚ะพะฝะพะฒ ะะฝ-225 ะœั€ั–ั, lit.โ€‰'dream' or 'inspiration'; NATO reporting name: Cossack) is a strategic airlift cargo aircraft that was designed by the Antonov Design Bureau in the Ukrainian SSR within the Soviet Union during the 1980s. Originally, this unique aircraft was developed as an enlargement of the Antonov An-124 to transport Buran-class orbiters. After successfully fulfilling its Soviet military missions, it was mothballed for eight years. It was then refurbished and reintroduced into commercial operation with Antonov Airlines, carrying oversized payloads. While a second airframe with a slightly different configuration was partially built, construction was halted more than once due to a lack of funding and interest. This second aircraft was last brought up to 60โ€“70% completion in 2009.

As an over sized aircraft the Antonov An-225 Mriya holds multiple records which include; heaviest aircraft ever built, and largest wingspan of any aircraft in operational service. Other records held by the An-225 are cargo related in terms of weight and length as the Antonov An-225 has the capability to carry up to 640 tonnes (705 short tons). The An-225 attracts a high degree of public interest, so much that it has managed to attain a global following due to its size and its uniqueness. People frequently visit airports to see its scheduled arrivals and departures.

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๐Ÿ”— Maxima (Software)

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

Maxima () is a computer algebra system (CAS) based on a 1982 version of Macsyma. It is written in Common Lisp and runs on all POSIX platforms such as macOS, Unix, BSD, and Linux, as well as under Microsoft Windows and Android. It is free software released under the terms of the GNU General Public License (GPL).

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๐Ÿ”— 2019 redefinition of the SI base units

๐Ÿ”— Physics

In 2019, the SI base units were redefined in agreement with the International System of Quantities, effective on the 144th anniversary of the Metre Convention, 20 May 2019. In the redefinition, four of the seven SI base units โ€“ the kilogram, ampere, kelvin, and mole โ€“ were redefined by setting exact numerical values for the Planck constant (h), the elementary electric charge (e), the Boltzmann constant (kB), and the Avogadro constant (NA), respectively. The second, metre, and candela were already defined by physical constants and were subject to correction to their definitions. The new definitions aimed to improve the SI without changing the value of any units, ensuring continuity with existing measurements. In November 2018, the 26th General Conference on Weights and Measures (CGPM) unanimously approved these changes, which the International Committee for Weights and Measures (CIPM) had proposed earlier that year after determining that previously agreed conditions for the change had been met.:23 These conditions were satisfied by a series of experiments that measured the constants to high accuracy relative to the old SI definitions, and were the culmination of decades of research.

The previous major change of the metric system occurred in 1960 when the International System of Units (SI) was formally published. At this time the metre was redefined: the definition was changed from the prototype of the metre to a certain number of wavelengths of a spectral line of a krypton-86 radiation, making it derivable from universal natural phenomena. The kilogram remained defined by a physical prototype, leaving it the only artefact upon which the SI unit definitions depend. At this time the SI, as a coherent system, was constructed around seven base units, powers of which were used to construct all other units. With the 2019 redefinition, the SI is constructed around seven defining constants, allowing all units to be constructed directly from these constants. The designation of base units is retained but is no longer essential to define SI measures.

The metric system was originally conceived as a system of measurement that was derivable from unchanging phenomena, but practical limitations necessitated the use of artefacts โ€“ the prototype of the metre and prototype of the kilogram โ€“ when the metric system was introduced in France in 1799. Although it was designed for long-term stability, the masses of the prototype kilogram and its secondary copies have shown small variations relative to each other over time; they are not thought to be adequate for the increasing accuracy demanded by science, prompting a search for a suitable replacement. The definitions of some units were defined by measurements that are difficult to precisely realise in a laboratory, such as the kelvin, which was defined in terms of the triple point of water. With the 2019 redefinition, the SI became wholly derivable from natural phenomena with most units being based on fundamental physical constants.

A number of authors have published criticisms of the revised definitions; their criticisms include the premise that the proposal failed to address the impact of breaking the link between the definition of the dalton and the definitions of the kilogram, the mole, and the Avogadro constant.

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๐Ÿ”— Zero Knowledge Proofs

๐Ÿ”— Cryptography ๐Ÿ”— Cryptography/Computer science

In cryptography, a zero-knowledge proof or zero-knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that they know a value x, without conveying any information apart from the fact that they know the value x. The essence of zero-knowledge proofs is that it is trivial to prove that one possesses knowledge of certain information by simply revealing it; the challenge is to prove such possession without revealing the information itself or any additional information.

If proving a statement requires that the prover possesses some secret information, then the verifier will not be able to prove the statement to anyone else without possessing the secret information. The statement being proved must include the assertion that the prover has such knowledge, but not the knowledge itself. Otherwise, the statement would not be proved in zero-knowledge because it provides the verifier with additional information about the statement by the end of the protocol. A zero-knowledge proof of knowledge is a special case when the statement consists only of the fact that the prover possesses the secret information.

Interactive zero-knowledge proofs require interaction between the individual (or computer system) proving their knowledge and the individual validating the proof.

A protocol implementing zero-knowledge proofs of knowledge must necessarily require interactive input from the verifier. This interactive input is usually in the form of one or more challenges such that the responses from the prover will convince the verifier if and only if the statement is true, i.e., if the prover does possess the claimed knowledge. If this were not the case, the verifier could record the execution of the protocol and replay it to convince someone else that they possess the secret information. The new party's acceptance is either justified since the replayer does possess the information (which implies that the protocol leaked information, and thus, is not proved in zero-knowledge), or the acceptance is spurious, i.e., was accepted from someone who does not actually possess the information.

Some forms of non-interactive zero-knowledge proofs exist, but the validity of the proof relies on computational assumptions (typically the assumptions of an ideal cryptographic hash function).

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๐Ÿ”— Cognitive distortion

๐Ÿ”— Psychology

A cognitive distortion is an exaggerated or irrational thought pattern involved in the onset and perpetuation of psychopathological states, especially those more influenced by psychosocial factors, such as depression and anxiety. Psychiatrist Aaron T. Beck laid the groundwork for the study of these distortions, and his student David D. Burns continued research on the topic. Burns, in Feeling Good the new Mood Therapy , described personal and professional anecdotes related to cognitive distortions and their elimination.

Cognitive distortions are thoughts that cause individuals to perceive reality inaccurately. According to the cognitive model of Beck, a negative outlook on reality, sometimes called negative schemas (or schemata), is a factor in symptoms of emotional dysfunction and poorer subjective well-being. Specifically, negative thinking patterns reinforce negative emotions and thoughts. During difficult circumstances, these distorted thoughts can contribute to an overall negative outlook on the world and a depressive or anxious mental state.

Challenging and changing cognitive distortions is a key element of cognitive behavioral therapy (CBT).