Random Articles (Page 3)
Have a deep view into what people are curious about.
π Alan Turing's 100th Birthday - Mathematician, logician, cryptanalyst, scientist
Alan Mathison Turing (; 23 June 1912Β β 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical computer science, providing a formalisation of the concepts of algorithm and computation with the Turing machine, which can be considered a model of a general-purpose computer. Turing is widely considered to be the father of theoretical computer science and artificial intelligence. Despite these accomplishments, he was not fully recognised in his home country during his lifetime, due to his homosexuality, and because much of his work was covered by the Official Secrets Act.
During the Second World War, Turing worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain's codebreaking centre that produced Ultra intelligence. For a time he led Hut 8, the section that was responsible for German naval cryptanalysis. Here, he devised a number of techniques for speeding the breaking of German ciphers, including improvements to the pre-war Polish bombe method, an electromechanical machine that could find settings for the Enigma machine.
Turing played a crucial role in cracking intercepted coded messages that enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in so doing helped win the war. Due to the problems of counterfactual history, it is hard to estimate the precise effect Ultra intelligence had on the war, but at the upper end it has been estimated that this work shortened the war in Europe by more than two years and saved over 14Β million lives.
After the war Turing worked at the National Physical Laboratory, where he designed the Automatic Computing Engine. The Automatic Computing Engine was one of the first designs for a stored-program computer. In 1948 Turing joined Max Newman's Computing Machine Laboratory, at the Victoria University of Manchester, where he helped develop the Manchester computers and became interested in mathematical biology. He wrote a paper on the chemical basis of morphogenesis and predicted oscillating chemical reactions such as the BelousovβZhabotinsky reaction, first observed in the 1960s.
Turing was prosecuted in 1952 for homosexual acts; the Labouchere Amendment of 1885 had mandated that "gross indecency" was a criminal offence in the UK. He accepted chemical castration treatment, with DES, as an alternative to prison. Turing died in 1954, 16 days before his 42nd birthday, from cyanide poisoning. An inquest determined his death as a suicide, but it has been noted that the known evidence is also consistent with accidental poisoning.
In 2009, following an Internet campaign, British Prime Minister Gordon Brown made an official public apology on behalf of the British government for "the appalling way he was treated". Queen Elizabeth II granted Turing a posthumous pardon in 2013. The Alan Turing law is now an informal term for a 2017 law in the United Kingdom that retroactively pardoned men cautioned or convicted under historical legislation that outlawed homosexual acts.
Discussed on
- "Alan Turing died 70 years ago" | 2024-06-07 | 103 Upvotes 136 Comments
- "Alan Turing's 100th Birthday - Mathematician, logician, cryptanalyst, scientist" | 2012-06-22 | 146 Upvotes 19 Comments
- "Happy Birthday, Alan Turing" | 2011-06-23 | 78 Upvotes 6 Comments
π SuperH
SuperH (or SH) is a 32-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems.
At the time of introduction, SuperH was notable for having fixed-length 16-bit instructions in spite of its 32-bit architecture. This was a novel approach; at the time, RISC processors always used an instruction size that was the same as the internal data width, typically 32-bits. Using smaller instructions had consequences, the register file was smaller and instructions were generally two-operand format. But for the market the SuperH was aimed at, this was a small price to pay for the improved memory and processor cache efficiency.
Later versions of the design, starting with SH-5, included both 16- and 32-bit instructions, with the 16-bit versions mapping onto the 32-bit version inside the CPU. This allowed the machine code to continue using the shorter instructions to save memory, while not demanding the amount of instruction decoding logic needed if they were completely separate instructions. This concept is now known as a compressed instruction set and is also used by other companies, the most notable example being ARM for its Thumb instruction set.
As of 2015, many of the original patents for the SuperH architecture are expiring and the SH-2 CPU has been reimplemented as open source hardware under the name J2.
Discussed on
- "SuperH" | 2021-12-04 | 147 Upvotes 68 Comments
π Cupellation
Cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore. The process is based on the principle that precious metals do not oxidise or react chemically, unlike the base metals, so when they are heated at high temperatures, the precious metals remain apart, and the others react, forming slags or other compounds.
Since the Early Bronze Age, the process was used to obtain silver from smelted lead ores. By the Middle Ages and the Renaissance, cupellation was one of the most common processes for refining precious metals. By then, fire assays were used for assaying minerals, that is, testing fresh metals such as lead and recycled metals to know their purity for jewellery and coin making. Cupellation is still in use today.
Discussed on
- "Cupellation" | 2021-11-25 | 24 Upvotes 2 Comments
π PermianβTriassic Extinction Event
The PermianβTriassic extinction event, also known as the PβTr extinction, the PβT extinction, the End-Permian Extinction, and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras, approximately 252 million years ago. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It was the largest known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct.
There is evidence for one to three distinct pulses, or phases, of extinction. Potential causes for those pulses include one or more large meteor impact events, massive volcanic eruptions (such as the Siberian Traps), and climate change brought on by large releases of underwater methane or methane-producing microbes.
The speed of the recovery from the extinction is disputed. Some scientists estimate that it took 10Β million years (until the Middle Triassic), due both to the severity of the extinction and because grim conditions returned periodically for another 5Β million years. However, studies in Bear Lake County, near Paris, Idaho, showed a relatively quick rebound in a localized Early Triassic marine ecosystem, taking around 2 million years to recover, suggesting that the impact of the extinction may have been felt less severely in some areas than others.
Discussed on
- "PermianβTriassic extinction event" | 2012-12-18 | 18 Upvotes 2 Comments
π Omega Point
The Omega Point is a theorized future event in which the entirety of the universe spirals toward a final point of unification. The term was invented by the French Jesuit Catholic priest Pierre Teilhard de Chardin (1881β1955). Teilhard argued that the Omega Point resembles the Christian Logos, namely Christ, who draws all things into himself, who in the words of the Nicene Creed, is "God from God", "Light from Light", "True God from True God", and "through him all things were made". In the Book of Revelation, Christ describes himself thrice as "the Alpha and the Omega, the beginning and the end". Several decades after Teilhard's death, the idea of the Omega Point was expanded upon in the writings of John David Garcia (1971), Paolo Soleri (1981), Frank Tipler (1994), and David Deutsch (1997).
π Wikimedia community ratifies Movement Charter; Wikimedia Foundation vetoes it
Discussed on
- "Wikimedia community ratifies Movement Charter; Wikimedia Foundation vetoes it" | 2024-07-23 | 38 Upvotes 10 Comments
π Esterel β Synchronous programming language for complex, reactive systems
Esterel is a synchronous programming language for the development of complex reactive systems. The imperative programming style of Esterel allows the simple expression of parallelism and preemption. As a consequence, it is well suited for control-dominated model designs.
The development of the language started in the early 1980s, and was mainly carried out by a team of Ecole des Mines de Paris and INRIA led by GΓ©rard Berry in France. Current compilers take Esterel programs and generate C code or hardware (RTL) implementations (VHDL or Verilog).
The language is still under development, with several compilers out. The commercial version of Esterel is the development environment Esterel Studio. The company that commercialize it (Synfora) initiated a normalization process with the IEEE in April 2007 however the working group (P1778) dissolved March 2011. The Esterel v7 Reference Manual Version v7 30 β initial IEEE standardization proposal is publicly available.
Discussed on
- "Esterel β Synchronous programming language for complex, reactive systems" | 2019-12-27 | 56 Upvotes 5 Comments
π Tetrapharmakos - Epicurus's remedy for leading the happiest possible life.
The Tetrapharmakos (ΟΞ΅ΟΟΞ±ΟΞ¬ΟΞΌΞ±ΞΊΞΏΟ) "four-part remedy" is a summary of the first four of the ΞΟΟΞΉΞ±ΞΉ ΞΟΞΎΞ±ΞΉ (Kuriai Doxai, the forty Epicurean Principal Doctrines given by Diogenes LaΓ«rtius in his Life of Epicurus) in Epicureanism, a recipe for leading the happiest possible life. They are recommendations to avoid anxiety or existential dread.
The "tetrapharmakos" was originally a compound of four drugs (wax, tallow, pitch and resin); the word has been used metaphorically by Roman-era Epicureans. to refer to the four remedies for healing the soul.
Discussed on
- "Tetrapharmakos - Epicurus's remedy for leading the happiest possible life." | 2009-12-16 | 32 Upvotes 11 Comments
π Object-relational impedance mismatch
The object-relational impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management system (RDBMS) is being served by an application program (or multiple application programs) written in an object-oriented programming language or style, particularly because objects or class definitions must be mapped to database tables defined by a relational schema.
The term object-relational impedance mismatch is derived from the electrical engineering term impedance matching.
Discussed on
- "Object-relational impedance mismatch" | 2017-07-16 | 17 Upvotes 6 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